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[Powered by Google Translate] [Review] [Quiz 0]

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>> [Lexi Ross, Tommy MacWilliam, Lucas Freitas, Joseph Ong] [Chuo Kikuu cha Harvard]

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>> [Hii ni CS50.] [CS50.TV]

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>> Hey, kila mtu.

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Karibu kikao mapitio kwa Quiz 0, ambayo ni kuchukua nafasi hii Jumatano.

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Nini sisi ni kwenda kufanya usiku wa leo, mimi nina kwa TFS 3 nyingine,

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na pamoja tunakwenda kupitia mapitio ya kile ambacho tumefanya katika shaka hadi sasa.

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Ni si kwenda kuwa 100% ya kina, lakini ni lazima kukupa wazo bora

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ya nini wewe tayari chini na kile bado unahitaji kujifunza kabla ya Jumatano.

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Na kujisikia huru kunyanyua mkono wako na maswali kama tunakwenda pamoja,

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lakini kukumbuka kwamba tutaweza pia kidogo kidogo ya muda katika mwisho-

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kama sisi kupata kupitia kwa dakika chache vipuri-kufanya maswali ya jumla,

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hivyo kuendelea kuwa katika akili, na hivyo sisi ni kwenda kuanza mwanzoni na Wiki 0.

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>> [Quiz 0 Review!] [Part 0] [Lexi Ross] Lakini kabla ya sisi kufanya hivyo hebu majadiliano kuhusu

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vifaa ya chemsha bongo.

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>> [Logistics] [Quiz unafanyika Jumatano 10/10 badala ya hotuba]

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>> [(Angalia http://cdn.cs50.net/2012/fall/quizzes/0/about0.pdf kwa maelezo zaidi)] Ni juu ya Jumatano, Oktoba 10.

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>> Hiyo ni hii Jumatano, na kama wewe kwenda URL hii hapa,

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ambayo pia ni kupatikana kutoka CS50.net-kuna zilizounganishwa na ni-

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unaweza kuona taarifa kuhusu ambapo kwenda kwa kuzingatia

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jina yako ya mwisho au kuyaunganisha shule kama vile

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ni anaelezea kuhusu nini hasa Jaribio itafikia na aina ya maswali kwamba wewe ni kwenda kupata.

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Kumbuka kwamba utapata pia kuwa na nafasi ya kupitia kwa chemsha bongo katika sehemu,

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hivyo TFS yako lazima kwenda juu ya matatizo ya baadhi ya mazoezi,

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na kwamba ni nafasi nyingine nzuri ya kuona ambapo wewe bado wanahitaji kujifunza kwa ajili ya chemsha bongo.

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Hebu kuanza mwanzoni na Bytes bits 'n'.

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Kumbuka kidogo tu ni 0 au 1,

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na Byte ni mkusanyiko wa 8 wa bits wale.

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Hebu tuangalie hii ukusanyaji wa bits haki hapa.

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Tunapaswa kuwa na uwezo wa kufikiri jinsi wengi bits kuna.

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Ambapo sisi kuhesabu kuna tu 8 wao, nane 0 au 1 vipande.

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Na tangu kuna 8 bits, hiyo ni 1 Byte,

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na hebu kubadilisha kwa hexadesimoli.

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Hexadesimoli ni msingi 16, na ni pretty rahisi kubadili

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idadi katika binary, ambayo ni kile kwamba ni, na idadi katika hexadesimoli.

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Wote sisi kufanya ni sisi kuangalia makundi ya 4,

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na sisi kubadili yao kwa tarakimu sahihi hexadesimoli.

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Tunaweza kuanza na kundi haki-zaidi ya 4, hivyo 0011.

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Hiyo inaenda kuwa moja na moja 1 2, hivyo pamoja kwamba inafanya 3.

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Na kisha hebu tuangalie block nyingine ya 4.

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1101. Hiyo inaenda kuwa moja 1, moja 4, na moja 8.

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Pamoja kwamba ni kwenda kuwa 13, ambayo inafanya D.

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Na tutaweza kukumbuka kwamba katika hexadesimoli sisi hawaendi tu 0 kupitia 9.

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Sisi kwenda 0 kupitia F, hivyo baada ya 9, sambamba 10 kwa,

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11 A na B, nakadhalika ambapo F ni 15.

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Hapa ni 13 D,

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hivyo kwa kubadilisha kwa decimal wote sisi kufanya ni sisi kweli

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kutibu kila nafasi kama nguvu ya 2.

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Hiyo ni moja 1, 2 moja, sifuri 4s, sifuri 8s, mmoja 16, nakadhalika,

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na ni kidogo ngumu kwa compute katika kichwa yako, lakini kama sisi kwenda slide ijayo

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tunaweza kuona jibu la kwamba.

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>> Kimsingi sisi ni kwenda hela kutoka kulia nyuma upande wa kushoto,

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na sisi ni kuzidisha kila tarakimu kwa nguvu sambamba ya 2.

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Na kumbuka, kwa hexadesimoli sisi kuashiria namba hizi kwa 0x mwanzoni

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hivyo hatuna kuchanganya hili na idadi decimal.

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Kuendelea juu, hii ni Jedwali ASCII,

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na kile sisi kutumia ASCII kwa ni ramani ya kutoka wahusika kwa maadili ya namba.

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Kumbuka katika pset cryptography sisi alifanya matumizi makubwa ya Jedwali ASCII

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ili kutumia mbinu mbalimbali za cryptography,

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Kaisari na cipher Vigenère, kubadili barua tofauti

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katika kamba kulingana na muhimu uliotolewa na mtumiaji.

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Hebu tuangalie kidogo ya math ASCII.

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Kuangalia 'P' + 1, katika tabia fomu kwamba itakuwa Q,

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na kukumbuka kwamba '5 '≠ 5.

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Na jinsi gani hasa ingekuwa sisi kubadilisha kati ya fomu hizo 2?

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Ni kweli si ngumu sana.

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Ili kupata 5 sisi Ondoa '0 '

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kwa sababu kuna maeneo 5 kati ya '0 'na '5'.

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Ili kwenda njia nyingine sisi tu kuongeza 0,

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hivyo ni aina ya kama hesabu ya mara kwa mara.

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Kumbuka tu kwamba wakati kitu ina quotes pembezoni ni tabia

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na hivyo sambamba na thamani katika meza ASCII.

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Kuhamia katika zaidi ya jumla ya mada sayansi ya kompyuta.

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Tulijifunza nini algorithm ni na jinsi ya kutumia programu

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kutekeleza algorithms.

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Baadhi ya mifano ya algorithms ni kitu rahisi kama kweli

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kuangalia kama idadi ni hata au isiyo ya kawaida.

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Kwa kuwa kumbuka sisi Mod idadi na 2 na kuangalia kama matokeo ni 0.

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Kama ni hivyo, ni hata. Kama siyo, ni isiyo ya kawaida.

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Na kwamba ni mfano wa algorithm kweli ya msingi.

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>> kidogo ya moja kushiriki zaidi ni binary tafuta,

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ambayo tutaweza kwenda juu ya baadaye katika kikao cha mapitio.

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Na programu hii ni mrefu sisi kutumia kwa ajili ya kuchukua algorithm

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na kuwageuza kwa code kompyuta unaweza kusoma.

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2 mifano ya programu ni Scratch,

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ambayo ni kile sisi alivyofanya katika Wiki 0.

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Hata ingawa sisi si kweli aina nje code ni njia ya kutekeleza

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hii algorithm, ambayo ni uchapishaji idadi 1-10,

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na hapa sisi kufanya hivyo katika lugha ya programu C.

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Hizi ni functionally sawa, tu yaliyoandikwa katika lugha tofauti au syntax.

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Sisi basi kujifunza kuhusu misemo bulin,

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na bulin ni thamani hiyo ni aidha kweli au uongo,

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na hapa mara nyingi bulin misemo

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kwenda ndani ya hali, hivyo kama (x ≤ 5),

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vizuri, sisi tayari kuweka x = 5, hivyo hali ya kuwa ni kwenda kutathmini kwa kweli.

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Na kama ni kweli, yo code ni chini ya hali

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ni kwenda kuwa tathmini na kompyuta, hivyo string kwamba ni kwenda kuwa kuchapishwa

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pato ya kiwango, na hali mrefu

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inahusu viliomo ndani ya mabano ya kauli kama.

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Kumbuka waendeshaji wote.

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Kumbuka && yake na | | wakati sisi ni kujaribu kuchanganya hali ya 2 au zaidi,

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== Si = kuangalia kama 2 mambo ni sawa.

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Kumbuka kwamba ni kwa ajili ya zoezi = ambapo == ni operator bulin.

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≤, ≥ na kisha 2 ya mwisho ni self-maelezo.

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mapitio ya jumla ya mantiki ya bulin hapa.

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Na maneno ya bulin ni muhimu pia katika tanzi,

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ambayo tutaweza kwenda juu sasa.

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Tulijifunza kuhusu aina 3 ya vitanzi hivyo mbali katika CS50, kwa, wakati, na kufanya wakati.

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Na ni muhimu kujua kwamba wakati kwa makusudi zaidi

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tunaweza kweli matumizi ya aina yoyote ya kitanzi ujumla

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kuna aina fulani ya makusudi au ruwaza ya kawaida

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katika programu ambayo hasa wito kwa moja ya matanzi hizi

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kwamba kufanya hivyo ni bora zaidi au kifahari kwa kificho katika njia hiyo.

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Hebu kwenda juu ya nini kila matanzi hizi huelekea kutumika kwa mara nyingi.

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>> Katika kwa kitanzi sisi ujumla tayari kujua jinsi mara nyingi tunataka iterate.

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Hiyo ni nini sisi kuweka katika hali hiyo.

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Kwa maana, i = 0, i <10, kwa mfano.

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Sisi tayari kujua kwamba tunataka kufanya kitu mara 10.

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Sasa, kwa kitanzi wakati, kwa ujumla hatuwezi si lazima

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kujua jinsi mara nyingi tunataka kitanzi kukimbia.

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Lakini sisi kujua aina fulani ya hali ya kuwa sisi unataka kwa

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daima kuwa kweli au daima kuwa uongo.

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Kwa mfano, wakati ni kuweka.

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Hebu kusema kwamba variable bulin.

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Wakati hiyo ni kweli tunataka code kutathmini,

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hivyo kidogo zaidi extensible, kidogo zaidi ya jumla kuliko kwa kitanzi,

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lakini yoyote kwa kitanzi pia inaweza kuongoka kwa kitanzi wakati.

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Hatimaye, kufanya wakati tanzi, ambayo inaweza kuwa trickiest kufahamu haki mbali,

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zinatumika mara nyingi wakati tunataka kutathmini code kwanza

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kabla ya wakati wa kwanza sisi kuangalia hali.

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matumizi ya pamoja kesi kwa kufanya wakati kitanzi

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ni wakati unataka kupata user pembejeo, na unajua unataka kuuliza mtumiaji

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kwa ajili ya pembejeo angalau mara moja, lakini kama hawana kukupa pembejeo nzuri haki mbali

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unataka kuendelea kuuliza nao mpaka kukupa pembejeo nzuri.

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Hiyo ni matumizi ya kawaida ya kufanya wakati kitanzi,

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na hebu tuangalie muundo halisi ya matanzi haya.

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Wao kawaida huwa daima kufuata ruwaza hizi.

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>> On kitanzi kwa ajili ya ndani una vipengele 3:

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initialization, kawaida kitu kama int i = 0 ambapo i ni counter,

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hali, ambapo tunataka kusema kukimbia hii kwa kitanzi kwa muda mrefu kama hali hii bado anashikilia,

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kama i <10, na kisha hatimaye, update, ambayo ni jinsi sisi increment

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variable counter katika kila hatua katika kitanzi.

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jambo la kawaida kuona kuna tu i + +,

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ambayo ina maana increment i na 1 kila wakati.

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Unaweza pia kufanya kitu kama i + = 2,

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ambayo ina maana ya kuongeza 2 na i kila wakati wewe kwenda kwa njia ya kitanzi.

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Na kisha kufanya hivyo tu inahusu yoyote kificho kwamba kweli anaendesha kama sehemu ya kitanzi.

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Na kwa kitanzi wakati, wakati huu sisi kweli kuwa initialization nje ya loop,

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hivyo kwa mfano, hebu kusema sisi ni kujaribu kufanya aina moja ya loop kama mimi tu ilivyoelezwa.

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Tunataka kusema int i = 0 kabla kitanzi huanza.

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Kisha tunaweza kusema wakati i <10 kufanya hili,

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hivyo kuzuia huo wa kanuni kama kabla,

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na wakati huu sehemu update ya kificho, kwa mfano, i + +,

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kweli inakwenda ndani ya kitanzi.

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Na hatimaye, kwa kufanya wakati, ni sawa na kitanzi wakati,

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lakini tunahitaji kukumbuka kwamba kanuni itakuwa kutathmini mara moja

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kabla hali ni checked, hivyo inafanya mengi zaidi akili

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kama ukiangalia kwa utaratibu wa juu hadi chini.

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Katika, kufanya wakati kitanzi code kutathmini kabla hata kuangalia hali wakati

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ambapo kitanzi wakati, hundi ya kwanza.

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Kauli na vigezo.

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Wakati tunataka kujenga variable mpya sisi kwanza unataka initialize yake.

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>> Kwa mfano, bar int initializes bar variable,

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lakini haina kuwapa thamani, hivyo ni nini thamani bar sasa?

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Hatujui.

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Ni inaweza kuwa baadhi ya thamani ya takataka kwamba awali alikuwa kuhifadhiwa katika kumbukumbu huko,

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na hatutaki kutumia kwamba variable

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mpaka sisi kweli kuwapa thamani,

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hivyo sisi kutangaza hapa.

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Kisha sisi initialize kuwa ni 42 chini.

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Sasa, bila shaka, tunajua hii inaweza kufanyika kwenye mstari mmoja, int bar = 42.

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Lakini tu kuwa wazi hatua mbalimbali ambayo ni kwenda,

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tamko na initialization yanayotokea tofauti hapa.

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Ni hufanyika kwenye hatua moja, na moja ijayo, int bazi = bar + 1,

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kauli hii hapa chini, kwamba bazi nyongeza, hivyo mwisho wa block hii code

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kama tulikuwa na magazeti thamani ya bazi itakuwa 44

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kwa sababu sisi kutangaza na initialize kuwa ni 1> bar,

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na kisha sisi increment mara moja zaidi na + +.

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Sisi akaenda juu ufupi hii pretty, lakini ni vizuri kuwa na jumla ya

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kuelewa nini threads na matukio ni.

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Sisi hasa alifanya hivyo katika Scratch,

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hivyo unaweza kufikiri ya nyuzi kama Mwandamano nyingi ya maadili ya

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mbio kwa wakati mmoja.

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Katika actuality, basi pengine si mbio wakati huo huo,

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lakini aina ya abstractly tunaweza kufikiria ni katika njia hiyo.

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00:11:17,000 --> 00:11:20,000
>> Katika Scratch, kwa mfano, tulikuwa na sprites nyingi.

187
00:11:20,000 --> 00:11:22,000
Ni inaweza kuwa utekelezaji code tofauti kwa wakati mmoja.

188
00:11:22,000 --> 00:11:26,000
Mtu anaweza kuwa kutembea wakati mwingine kusema kitu

189
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katika sehemu mbalimbali ya screen.

190
00:11:29,000 --> 00:11:34,000
Matukio ni njia nyingine ya kujitenga kutoka mantiki

191
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kati ya mambo mbalimbali ya code yako,

192
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na katika Scratch tulikuwa na uwezo wa kuigiza matukio kutumia Broadcast,

193
00:11:40,000 --> 00:11:43,000
na hiyo ni kweli Wakati mimi Pokea, si Wakati mimi Sikieni,

194
00:11:43,000 --> 00:11:47,000
lakini kimsingi ni njia ya kutangaza habari

195
00:11:47,000 --> 00:11:49,000
kutoka sprite mmoja hadi mwingine.

196
00:11:49,000 --> 00:11:52,000
Kwa mfano, unaweza kutaka kusambaza mchezo juu,

197
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na wakati mwingine sprite inapata mchezo juu,

198
00:11:56,000 --> 00:11:58,000
inavyopokea katika njia fulani.

199
00:11:58,000 --> 00:12:03,000
Ni mfano wa kuigwa muhimu kuelewa kwa programu.

200
00:12:03,000 --> 00:12:07,000
Tu kwenda juu ya Wiki ya msingi 0, nini tumeenda juu hadi sasa,

201
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hebu tuangalie mpango huu rahisi C.

202
00:12:10,000 --> 00:12:14,000
Nakala inaweza kuwa kidogo kidogo kutoka hapa, lakini mimi nitakwenda juu yake kweli haraka.

203
00:12:14,000 --> 00:12:20,000
Sisi ni pamoja na files header 2 saa ya juu, na cs50.h stdio.h.

204
00:12:20,000 --> 00:12:23,000
Sisi ni mara kwa mara kisha kufasili kuitwa kikomo kuwa 100.

205
00:12:23,000 --> 00:12:26,000
Sisi ni kisha kutekeleza kazi yetu kuu.

206
00:12:26,000 --> 00:12:29,000
Tangu sisi si kutumia hoja mstari amri hapa tunahitaji kuweka utupu

207
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kama hoja kwa kuu.

208
00:12:32,000 --> 00:12:38,000
Tunaona int juu kuu. Hiyo ni aina ya kurudi, hivyo kurudi 0 chini.

209
00:12:38,000 --> 00:12:41,000
Na sisi ni kutumia CS50 maktaba kazi kupata int

210
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kuuliza mtumiaji kwa ajili ya pembejeo, na sisi kuhifadhi katika x hii variable,

211
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hivyo sisi kutangaza x hapo juu, na sisi initialize kwa x = GetInt.

212
00:12:51,000 --> 00:12:53,000
>> Sisi basi kuangalia kuona kama mtumiaji alitupa pembejeo nzuri.

213
00:12:53,000 --> 00:12:59,000
Kama ni ≥ LIMIT tunataka kurudi code makosa ya 1 na magazeti ujumbe wa kosa.

214
00:12:59,000 --> 00:13:02,000
Na hatimaye, kama mtumiaji ametupa nzuri pembejeo

215
00:13:02,000 --> 00:13:08,000
tunakwenda mraba namba na magazeti nje kwamba matokeo.

216
00:13:08,000 --> 00:13:11,000
Tu kuhakikisha kwamba wale wote nyumbani hit

217
00:13:11,000 --> 00:13:17,000
unaweza kuona maandiko ya sehemu mbalimbali za code hapa.

218
00:13:17,000 --> 00:13:19,000
Nilivyoeleza mara kwa mara, files header.

219
00:13:19,000 --> 00:13:21,000
Oh, int x. Hakikisha kukumbuka kwamba variable mitaa.

220
00:13:21,000 --> 00:13:24,000
Hiyo analinganisha ni kutoka variable kimataifa, ambayo tutaweza majadiliano juu ya

221
00:13:24,000 --> 00:13:27,000
kidogo kidogo baadaye katika kikao cha mapitio,

222
00:13:27,000 --> 00:13:30,000
na sisi ni wito kazi maktaba printf,

223
00:13:30,000 --> 00:13:34,000
hivyo kama sisi alikuwa si pamoja stdio.h header faili

224
00:13:34,000 --> 00:13:37,000
sisi isingekuwa na uwezo wa kuwaita printf.

225
00:13:37,000 --> 00:13:42,000
Na naamini arrow kwamba got kukatwa hapa ni akizungumzia d%,

226
00:13:42,000 --> 00:13:45,000
ambayo ni string formatting katika printf.

227
00:13:45,000 --> 00:13:52,000
Ni anasema magazeti nje hii variable kama d idadi,%.

228
00:13:52,000 --> 00:13:58,000
Na kwamba ni kwa ajili ya Wiki 0.

229
00:13:58,000 --> 00:14:06,000
Sasa Lucas ni kwenda kuendelea.

230
00:14:06,000 --> 00:14:08,000
Hey, guys. Jina langu ni Lucas.

231
00:14:08,000 --> 00:14:10,000
Mimi nina sophomore katika nyumba bora juu ya chuo, Mather,

232
00:14:10,000 --> 00:14:14,000
na mimi nina kwenda kuzungumza kidogo kuhusu Wiki 1 na 2.1.

233
00:14:14,000 --> 00:14:16,000
[Wiki 1 na 2.1!] [Lucas Freitas]

234
00:14:16,000 --> 00:14:19,000
Kama Lexi alikuwa akisema, wakati sisi ilianza kutafsiri code yako kutoka kwa Scratch C

235
00:14:19,000 --> 00:14:23,000
moja ya mambo ambayo sisi niliona ni kwamba unaweza tu

236
00:14:23,000 --> 00:14:26,000
kuandika code yako na kukimbia kwa kutumia bendera ya kijani tena.

237
00:14:26,000 --> 00:14:30,000
Kweli, una kutumia baadhi ya hatua na kufanya yako C mpango

238
00:14:30,000 --> 00:14:33,000
kuwa faili la kutekelezwa.

239
00:14:33,000 --> 00:14:36,000
Kimsingi nini unaweza kufanya wakati wewe ni kuandika mpango ni kwamba

240
00:14:36,000 --> 00:14:40,000
wewe kutafsiri wazo lako katika lugha ya kwamba compiler anaweza kuelewa,

241
00:14:40,000 --> 00:14:44,000
hivyo wakati wewe ni kuandika mpango katika C

242
00:14:44,000 --> 00:14:47,000
kile unachokifanya ni kweli kuandika kitu ambacho compiler yako anaenda kuelewa,

243
00:14:47,000 --> 00:14:50,000
na kisha compiler ni kwenda kutafsiri kwamba kanuni

244
00:14:50,000 --> 00:14:53,000
katika kitu ambacho kompyuta yako, wataelewa.

245
00:14:53,000 --> 00:14:55,000
>> Na jambo lenyewe, kompyuta yako ni kweli sana bubu.

246
00:14:55,000 --> 00:14:57,000
Kompyuta yako inaweza tu kuelewa na sekunde 0 1s,

247
00:14:57,000 --> 00:15:01,000
hivyo kweli katika kompyuta ya kwanza kwa kawaida watu iliyowekwa

248
00:15:01,000 --> 00:15:04,000
kutumia sekunde 0 na 1s, lakini si tena, kumshukuru Mungu.

249
00:15:04,000 --> 00:15:07,000
Hatuna kukariri Mwandamano kwa sekunde 0 na 1s

250
00:15:07,000 --> 00:15:10,000
kwa ajili ya kitanzi au kwa kitanzi wakati na kadhalika.

251
00:15:10,000 --> 00:15:13,000
Hiyo ndiyo sababu tuna compiler.

252
00:15:13,000 --> 00:15:17,000
Nini compiler gani ni kimsingi hutafsiriwa code C,

253
00:15:17,000 --> 00:15:21,000
katika kesi yetu, kwa lugha ya kwamba kompyuta yako wataelewa,

254
00:15:21,000 --> 00:15:25,000
ambayo ni code kitu, na compiler kwamba sisi ni kutumia

255
00:15:25,000 --> 00:15:30,000
inaitwa Clang, hivyo hii ni kweli alama kwa Clang.

256
00:15:30,000 --> 00:15:33,000
Wakati una mpango wako, una kufanya mambo 2.

257
00:15:33,000 --> 00:15:37,000
Kwanza, una mpango wa kukusanya yako, na kisha utaenda kuendesha programu yako.

258
00:15:37,000 --> 00:15:41,000
Kukusanya mpango wako una mengi ya chaguzi za kufanya hivyo.

259
00:15:41,000 --> 00:15:44,000
moja ya kwanza ni kufanya Clang program.c

260
00:15:44,000 --> 00:15:47,000
katika mpango ambayo ni jina la mpango wako.

261
00:15:47,000 --> 00:15:51,000
Katika kesi hii unaweza kuona wao ni kusema tu "Hey, kukusanya mpango wangu."

262
00:15:51,000 --> 00:15:56,000
Wewe si kusema "Nataka hii jina kwa ajili ya mpango wangu" au kitu chochote.

263
00:15:56,000 --> 00:15:58,000
>> chaguo la pili ni kutoa jina kwa programu yako.

264
00:15:58,000 --> 00:16:02,000
Unaweza kusema Clang-o na kisha jina kwamba unataka

265
00:16:02,000 --> 00:16:06,000
faili executable kutajwa kama na kisha program.c.

266
00:16:06,000 --> 00:16:11,000
Na unaweza pia kufanya kufanya mpango, na kuona jinsi katika kwanza 2 kesi

267
00:16:11,000 --> 00:16:15,000
Mimi kuweka c., Na katika moja ya tatu tu mimi kuwa na programu?

268
00:16:15,000 --> 00:16:18,000
Yeah, wewe kweli haipaswi kuweka c. Wakati matumizi ya kufanya.

269
00:16:18,000 --> 00:16:22,000
Vinginevyo compiler ni kweli kwenda yell saa wewe.

270
00:16:22,000 --> 00:16:24,000
Na pia, mimi sijui kama wewe guys kumbuka,

271
00:16:24,000 --> 00:16:29,000
lakini mara nyingi sisi pia kutumika-lcs50 au-LM.

272
00:16:29,000 --> 00:16:31,000
Hiyo inaitwa kuunganisha.

273
00:16:31,000 --> 00:16:35,000
Ni tu anamwambia compiler kwamba utatumia maktaba wale haki pale,

274
00:16:35,000 --> 00:16:39,000
hivyo kama unataka kutumia cs50.h wewe kweli kuwa na aina

275
00:16:39,000 --> 00:16:43,000
Clang program.c-lcs50.

276
00:16:43,000 --> 00:16:45,000
Kama huna kufanya hivyo, compiler si kwenda kujua

277
00:16:45,000 --> 00:16:50,000
kwamba wewe ni kutumia kazi hizo katika cs50.h.

278
00:16:50,000 --> 00:16:52,000
Na wakati unataka kuendesha programu yako una chaguzi 2.

279
00:16:52,000 --> 00:16:57,000
Kama alivyofanya Clang program.c hukutoa jina kwa programu yako.

280
00:16:57,000 --> 00:17:01,000
Una kukimbia kutumia. / A.out.

281
00:17:01,000 --> 00:17:06,000
A.out ni jina kiwango kwamba Clang anatoa mpango wako kama huna kuwapa jina.

282
00:17:06,000 --> 00:17:11,000
Vinginevyo wewe kwenda kufanya. / Mpango kama wewe alitoa jina kwa mpango wako,

283
00:17:11,000 --> 00:17:15,000
na pia kama wewe alifanya kufanya mpango jina kwamba mpango ni kwenda kupata

284
00:17:15,000 --> 00:17:23,000
tayari kwenda kuwa programmed jina moja kama faili c.

285
00:17:23,000 --> 00:17:26,000
Kisha tuliongea kuhusu aina ya data na data.

286
00:17:26,000 --> 00:17:31,000
>> Kimsingi data aina ni kitu kimoja kama masanduku kidogo wao kutumia

287
00:17:31,000 --> 00:17:35,000
kuhifadhi maadili, hivyo data aina ni kweli tu kama Pokémons.

288
00:17:35,000 --> 00:17:39,000
Wao kuja katika ukubwa wote na aina.

289
00:17:39,000 --> 00:17:43,000
Mimi sijui kama mlinganisho kwamba hufanya akili.

290
00:17:43,000 --> 00:17:46,000
ukubwa data kweli inategemea usanifu mashine.

291
00:17:46,000 --> 00:17:49,000
Ukubwa wote data kwamba nitakacho kuonyesha hapa

292
00:17:49,000 --> 00:17:53,000
ni kweli kwa mashine 32-bit, ambayo ni kesi ya appliance yetu,

293
00:17:53,000 --> 00:17:56,000
lakini kama wewe ni kweli coding Mac yako au katika Windows pia

294
00:17:56,000 --> 00:17:59,000
pengine wewe utaenda kuwa na mashine ya 64-bit,

295
00:17:59,000 --> 00:18:03,000
hivyo kumbuka kwamba ukubwa data kwamba nitakacho kuonyesha hapa

296
00:18:03,000 --> 00:18:06,000
ni kwa ajili ya mashine 32-bit.

297
00:18:06,000 --> 00:18:08,000
moja ya kwanza kuwa tuliona alikuwa int,

298
00:18:08,000 --> 00:18:10,000
ambayo ni pretty moja kwa moja.

299
00:18:10,000 --> 00:18:13,000
Wewe kutumia int kuhifadhi integer.

300
00:18:13,000 --> 00:18:16,000
Tuliona pia tabia, char.

301
00:18:16,000 --> 00:18:20,000
Kama unataka kutumia barua au ishara kidogo pengine wewe kwenda kutumia Char.

302
00:18:20,000 --> 00:18:26,000
Char ana 1 Byte, ambayo ina maana bits 8, kama Lexi alisema.

303
00:18:26,000 --> 00:18:31,000
Kimsingi tuna Jedwali ASCII ambayo ina 256

304
00:18:31,000 --> 00:18:34,000
iwezekanavyo michanganyiko ya sekunde 0 na 1s,

305
00:18:34,000 --> 00:18:37,000
na kisha pale unapoandika Char itakavyo kutafsiri

306
00:18:37,000 --> 00:18:44,000
tabia ya kuwa wewe pembejeo idadi kuwa katika meza ASCII, kama Lexi alisema.

307
00:18:44,000 --> 00:18:48,000
Sisi pia kuwa kuelea, ambayo sisi kutumia na kuhifadhi idadi decimal.

308
00:18:48,000 --> 00:18:53,000
Kama unataka kuchagua 3.14, kwa mfano, wewe utaenda kuutumia kuelea

309
00:18:53,000 --> 00:18:55,000
au mara mbili ambayo ina zaidi na usahihi.

310
00:18:55,000 --> 00:18:57,000
kuelea ana ka 4.

311
00:18:57,000 --> 00:19:01,000
mara mbili ana ka 8, hivyo tofauti tu ni usahihi.

312
00:19:01,000 --> 00:19:04,000
Sisi pia kuwa kwa muda mrefu kwamba ni kutumika kwa integers,

313
00:19:04,000 --> 00:19:09,000
na unaweza kuona kwa mashine 32-bit int na muda mrefu na ukubwa huo,

314
00:19:09,000 --> 00:19:13,000
hivyo ni kweli haina mantiki ya kutumia muda katika mashine ya 32-bit.

315
00:19:13,000 --> 00:19:17,000
>> Lakini kama wewe ni kutumia mashine Mac na 64-bit, kwa kweli kwa muda mrefu ina ukubwa 8,

316
00:19:17,000 --> 00:19:19,000
hivyo ni kweli inategemea usanifu.

317
00:19:19,000 --> 00:19:22,000
Kwa ajili ya mashine 32-bit haina mantiki ya kutumia muda mrefu kweli.

318
00:19:22,000 --> 00:19:25,000
Na kisha muda mrefu, kwa upande mwingine, ina ka 8,

319
00:19:25,000 --> 00:19:30,000
hivyo ni vizuri sana kama unataka kuwa integer tena.

320
00:19:30,000 --> 00:19:34,000
Na hatimaye, tuna kamba, ambayo ni kweli * Char,

321
00:19:34,000 --> 00:19:37,000
ambayo ni pointer Char.

322
00:19:37,000 --> 00:19:40,000
Ni rahisi sana kufikiri kwamba ukubwa wa string ni kwenda kuwa kama

323
00:19:40,000 --> 00:19:42,000
idadi ya herufi kwamba una pale,

324
00:19:42,000 --> 00:19:45,000
lakini kwa kweli * Char yenyewe

325
00:19:45,000 --> 00:19:49,000
ina ukubwa wa pointer Char, ambayo ni 4 ka.

326
00:19:49,000 --> 00:19:52,000
ukubwa wa * Char ni 4 ka.

327
00:19:52,000 --> 00:19:56,000
Haijalishi kama una neno dogo au barua au kitu chochote.

328
00:19:56,000 --> 00:19:58,000
Ni kwenda kuwa 4 ka.

329
00:19:58,000 --> 00:20:01,000
Tulijifunza pia kidogo kuhusu akitoa,

330
00:20:01,000 --> 00:20:04,000
hivyo kama unaweza kuona, kama una, kwa mfano, mpango kwamba anasema

331
00:20:04,000 --> 00:20:08,000
int x = 3 na kisha printf ("% d", x / 2)

332
00:20:08,000 --> 00:20:12,000
kufanya wewe guys kujua nini kinaendelea na magazeti juu ya screen?

333
00:20:12,000 --> 00:20:14,000
>> Mtu >> [Wanafunzi]? 2.

334
00:20:14,000 --> 00:20:16,000
1. >> 1, yeah.

335
00:20:16,000 --> 00:20:20,000
Wakati wa kufanya 3/2 ni kwenda kupata 1.5,

336
00:20:20,000 --> 00:20:24,000
lakini tangu sisi ni kutumia integer itakavyo kupuuza sehemu decimal,

337
00:20:24,000 --> 00:20:26,000
na mtaenda kuwa 1.

338
00:20:26,000 --> 00:20:29,000
Kama hutaki kuwa kutokea nini unaweza kufanya, kwa mfano,

339
00:20:29,000 --> 00:20:33,000
ni kutangaza kuelea y = x.

340
00:20:33,000 --> 00:20:40,000
Kisha x kwamba kutumika kuwa 3 sasa ni kwenda kuwa 3.000 katika y.

341
00:20:40,000 --> 00:20:44,000
Na kisha unaweza magazeti y / 2.

342
00:20:44,000 --> 00:20:50,000
Kweli, mimi wanapaswa kuwa na 2. zaidi ya hapo.

343
00:20:50,000 --> 00:20:55,000
Ni kwenda kufanya 3.00/2.00,

344
00:20:55,000 --> 00:20:58,000
na wewe ni kwenda kupata 1.5.

345
00:20:58,000 --> 00:21:06,000
Na tuna hii f 0.2 tu ya kuuliza kwa ajili ya vitengo 2 decimal katika sehemu decimal.

346
00:21:06,000 --> 00:21:12,000
Kama una f 0.3 itakavyo kuwa kweli 1.500.

347
00:21:12,000 --> 00:21:16,000
Kama ni 2 itakavyo kuwa 1.50.

348
00:21:16,000 --> 00:21:18,000
Sisi pia kuwa kesi hii hapa.

349
00:21:18,000 --> 00:21:22,000
Kama wewe kufanya kuelea x = 3.14 na basi printf x

350
00:21:22,000 --> 00:21:24,000
wewe ni kwenda kupata 3.14.

351
00:21:24,000 --> 00:21:29,000
Na kama wewe kufanya x = int ya x,

352
00:21:29,000 --> 00:21:34,000
ambayo ina maana ya kutibu x kama int na wewe magazeti x sasa

353
00:21:34,000 --> 00:21:36,000
wewe utaenda kuwa na 3.00.

354
00:21:36,000 --> 00:21:38,000
Je, hiyo mantiki?

355
00:21:38,000 --> 00:21:41,000
Kwa sababu wewe ni wa kwanza kutibu x kama integer, hivyo wewe ni kupuuza sehemu decimal,

356
00:21:41,000 --> 00:21:45,000
na kisha wewe ni uchapishaji x.

357
00:21:45,000 --> 00:21:47,000
Na hatimaye, unaweza pia kufanya hivyo,

358
00:21:47,000 --> 00:21:52,000
int x = 65, na kisha kutangaza Char c = x,

359
00:21:52,000 --> 00:21:56,000
na kisha kama magazeti c wewe ni kweli kwenda kupata

360
00:21:56,000 --> 00:21:59,000
, Hivyo kimsingi kile unachokifanya hapa

361
00:21:59,000 --> 00:22:02,000
na kutafsiri integer katika tabia,

362
00:22:02,000 --> 00:22:05,000
tu kama Jedwali ASCII gani.

363
00:22:05,000 --> 00:22:08,000
Sisi pia alizungumzia waendeshaji math.

364
00:22:08,000 --> 00:22:14,000
Wengi wao ni pretty moja kwa moja, hivyo +, -, *, /,

365
00:22:14,000 --> 00:22:20,000
na pia kuongelea Mod, ambayo ni salio ya mgawanyiko wa idadi 2.

366
00:22:20,000 --> 00:22:23,000
Kama una 10% 3, kwa mfano,

367
00:22:23,000 --> 00:22:27,000
maana kugawanya 10 na 3, na nini ni salio?

368
00:22:27,000 --> 00:22:30,000
Ni kwenda kuwa 1, hivyo ni muhimu sana kwa kweli mengi ya mipango.

369
00:22:30,000 --> 00:22:38,000
Kwa Vigenère na Kaisari nina uhakika pretty kuwa wote nyie kutumika Mod.

370
00:22:38,000 --> 00:22:43,000
Kuhusu waendeshaji math, kuwa makini sana wakati kuchanganya * na /.

371
00:22:43,000 --> 00:22:48,000
>> Kwa mfano, kama wewe kufanya (3/2) * 2 nini wewe ni kwenda kupata?

372
00:22:48,000 --> 00:22:50,000
[Wanafunzi] 2.

373
00:22:50,000 --> 00:22:54,000
Yeah, 2, kwa sababu 3/2 ni kwenda kuwa 1.5,

374
00:22:54,000 --> 00:22:57,000
lakini tangu unafanya shughuli kati ya integers 2

375
00:22:57,000 --> 00:22:59,000
wewe ni kweli kwenda tu kufikiria 1,

376
00:22:59,000 --> 00:23:03,000
na kisha 1 * 2 ni kwenda kuwa 2, hivyo kuwa mwangalifu sana

377
00:23:03,000 --> 00:23:07,000
wakati wa kufanya hesabu kwa sababu integers

378
00:23:07,000 --> 00:23:12,000
unaweza kupata kwamba 2 = 3, katika kesi hiyo.

379
00:23:12,000 --> 00:23:14,000
Na pia kuwa makini sana juu ya kuendelezwa.

380
00:23:14,000 --> 00:23:21,000
Unapaswa kawaida kutumia mabano kuwa na uhakika kwamba unajua nini unachokifanya.

381
00:23:21,000 --> 00:23:27,000
Baadhi ya njia za mkato muhimu, bila shaka, moja ni i + + + au i = 1

382
00:23:27,000 --> 00:23:30,000
au kutumia + =.

383
00:23:30,000 --> 00:23:34,000
Hiyo ni kitu kimoja kama kufanya i = i + 1.

384
00:23:34,000 --> 00:23:39,000
Unaweza pia kufanya i - au i - = 1,

385
00:23:39,000 --> 00:23:42,000
ambayo ni kitu sawa kama i = i -1,

386
00:23:42,000 --> 00:23:46,000
kitu wewe guys matumizi mengi katika kwa tanzi, angalau.

387
00:23:46,000 --> 00:23:52,000
Pia, kwa ajili ya *, kama matumizi * = na kama wewe, kwa mfano,

388
00:23:52,000 --> 00:23:57,000
i * = 2 ni kitu sawa na kusema i = i * 2,

389
00:23:57,000 --> 00:23:59,000
na kitu kimoja kwa ajili ya mgawanyo.

390
00:23:59,000 --> 00:24:08,000
Kama wewe kufanya i / = 2 ni kitu sawa kama i = i / 2.

391
00:24:08,000 --> 00:24:10,000
>> Sasa kuhusu utendaji.

392
00:24:10,000 --> 00:24:13,000
You guys kujifunza kwamba kazi ni mkakati mzuri sana kuokoa code

393
00:24:13,000 --> 00:24:16,000
wakati wewe programu, hivyo kama unataka kufanya kazi sawa

394
00:24:16,000 --> 00:24:20,000
katika code tena na tena, pengine unataka kutumia kazi

395
00:24:20,000 --> 00:24:25,000
hivyo tu huna na nakala na kuweka code juu na juu tena.

396
00:24:25,000 --> 00:24:28,000
Kweli, kuu ni kazi, na wakati mimi kuonyesha muundo wa kazi

397
00:24:28,000 --> 00:24:32,000
wewe utaenda kuona kwamba ni pretty wazi.

398
00:24:32,000 --> 00:24:35,000
Sisi pia kutumia kazi kutoka maktaba baadhi,

399
00:24:35,000 --> 00:24:39,000
kwa mfano, printf, GetIn, ambayo ni kutoka maktaba CS50,

400
00:24:39,000 --> 00:24:43,000
na kazi nyingine kama toupper.

401
00:24:43,000 --> 00:24:46,000
Wote wa kazi hizo ni kweli kutekelezwa katika maktaba nyingine,

402
00:24:46,000 --> 00:24:49,000
na wakati kuweka files wale tether katika mwanzo wa mpango wako

403
00:24:49,000 --> 00:24:53,000
wewe ni kusema unaweza tafadhali nipe code kwa kazi hizo

404
00:24:53,000 --> 00:24:57,000
hivyo sina kuitekeleza kwa mwenyewe?

405
00:24:57,000 --> 00:25:00,000
Na unaweza pia kuandika yako kazi wenyewe, hivyo wakati wa kuanza programu

406
00:25:00,000 --> 00:25:04,000
wewe kutambua kwamba maktaba hawana kazi zote kwamba unahitaji.

407
00:25:04,000 --> 00:25:10,000
Kwa pset mwisho, kwa mfano, sisi aliandika kuteka, kinyang'anyiro, na Luke,

408
00:25:10,000 --> 00:25:13,000
na ni sana, ni muhimu sana kuwa na uwezo wa kuandika kazi

409
00:25:13,000 --> 00:25:17,000
kwa sababu wao ni muhimu, na sisi kutumia muda wao wote katika programu,

410
00:25:17,000 --> 00:25:19,000
na anaokoa mengi ya code.

411
00:25:19,000 --> 00:25:21,000
muundo wa kazi ni hii moja.

412
00:25:21,000 --> 00:25:24,000
Tuna kurudi aina katika mwanzo. Je, ni aina ya kurudi?

413
00:25:24,000 --> 00:25:27,000
Ni tu wakati kazi yako ni kwenda na kurudi.

414
00:25:27,000 --> 00:25:29,000
Kama una kazi, kwa mfano, factorial,

415
00:25:29,000 --> 00:25:31,000
kwamba ni kwenda kwa mahesabu ya factorial integer,

416
00:25:31,000 --> 00:25:34,000
pengine ni kwenda na kurudi integer pia.

417
00:25:34,000 --> 00:25:37,000
Basi aina ya kurudi ni kwenda kuwa int.

418
00:25:37,000 --> 00:25:41,000
Printf kweli ina aina kurudi tupu

419
00:25:41,000 --> 00:25:43,000
kwa sababu wewe si kurudi chochote.

420
00:25:43,000 --> 00:25:45,000
Wewe tu uchapishaji mambo screen

421
00:25:45,000 --> 00:25:48,000
na kuacha kazi baadaye.

422
00:25:48,000 --> 00:25:51,000
Kisha una jina la kazi ambayo unaweza kuchagua.

423
00:25:51,000 --> 00:25:55,000
Unapaswa kuwa kidogo nafuu, kama huna kuchagua jina kama XYZ

424
00:25:55,000 --> 00:25:58,000
au kama x2f.

425
00:25:58,000 --> 00:26:02,000
Jaribu kufanya juu ya jina kwamba hufanya akili.

426
00:26:02,000 --> 00:26:04,000
>> Kwa mfano, kama ni factorial, kusema factorial.

427
00:26:04,000 --> 00:26:08,000
Kama ni kazi ambayo ni kwenda kuteka kitu, jina hilo kuteka.

428
00:26:08,000 --> 00:26:11,000
Na kisha tuna vigezo, ambayo pia inaitwa hoja,

429
00:26:11,000 --> 00:26:14,000
ambayo ni kama rasilimali kwamba kazi yako inahitaji

430
00:26:14,000 --> 00:26:17,000
kutoka code yako kufanya kazi yake.

431
00:26:17,000 --> 00:26:20,000
Kama unataka kufanya mahesabu factorial ya idadi

432
00:26:20,000 --> 00:26:23,000
pengine unahitaji kuwa na idadi ya hesabu factorial.

433
00:26:23,000 --> 00:26:27,000
Moja ya hoja kwamba utaenda kuwa ni namba yenyewe.

434
00:26:27,000 --> 00:26:31,000
Na basi ni kwenda kufanya kitu na kurudi thamani mwishoni

435
00:26:31,000 --> 00:26:35,000
isipokuwa ni kazi tupu.

436
00:26:35,000 --> 00:26:37,000
Hebu angalia mfano.

437
00:26:37,000 --> 00:26:40,000
Kama nataka kuandika kazi kwamba sums namba zote katika safu ya integers,

438
00:26:40,000 --> 00:26:43,000
Awali ya yote, aina ya kurudi ni kwenda kuwa int

439
00:26:43,000 --> 00:26:46,000
kwa sababu mimi na safu ya integers.

440
00:26:46,000 --> 00:26:51,000
Na kisha mimi naenda kuwa jina kazi kama sumArray,

441
00:26:51,000 --> 00:26:54,000
na kisha kwenda kuchukua safu yenyewe, kwa nums int,

442
00:26:54,000 --> 00:26:58,000
na kisha urefu wa safu hivyo najua jinsi wengi idadi nina jumla.

443
00:26:58,000 --> 00:27:02,000
Basi nina initialize variable kuitwa jumla, kwa mfano, 0,

444
00:27:02,000 --> 00:27:08,000
na kila wakati mimi kuona kipengele katika safu mimi autoe kwa jumla, hivyo sikuwa kwa kitanzi.

445
00:27:08,000 --> 00:27:15,000
Tu kama Lexi alisema, unaweza kufanya int i = 0, i <urefu na i + +.

446
00:27:15,000 --> 00:27:20,000
Na kwa kila kipengele katika safu sikuwa Jumla + = nums [i],

447
00:27:20,000 --> 00:27:24,000
na kisha nikarudi Jumla, hivyo ni rahisi sana, na anaokoa mengi ya maadili ya

448
00:27:24,000 --> 00:27:28,000
kama wewe ni kutumia kazi hii mara nyingi.

449
00:27:28,000 --> 00:27:32,000
Kisha sisi alichukua kuangalia hali.

450
00:27:32,000 --> 00:27:38,000
Tuna ikiwa, kingine, na kingine kama.

451
00:27:38,000 --> 00:27:42,000
Hebu angalia ni nini tofauti kati ya hizo.

452
00:27:42,000 --> 00:27:45,000
Kuangalia namba hizi 2. Nini tofauti kati yao?

453
00:27:45,000 --> 00:27:49,000
moja ya kwanza ina-kimsingi codes nataka uiambie

454
00:27:49,000 --> 00:27:51,000
kama idadi ni +, -, au 0.

455
00:27:51,000 --> 00:27:55,000
moja ya kwanza anasema kama ni> 0 basi ni chanya.

456
00:27:55,000 --> 00:28:00,000
Kama ni = 0 kwa basi ni 0, na kama ni <0 basi ni hasi.

457
00:28:00,000 --> 00:28:04,000
>> Na mtu mwingine ni kufanya kama, mwingine kama, mwingine.

458
00:28:04,000 --> 00:28:07,000
tofauti kati ya mbili ni kwamba moja hii ni kweli kwenda

459
00:28:07,000 --> 00:28:13,000
kuangalia kama> 0, <0 au = 0 mara tatu,

460
00:28:13,000 --> 00:28:17,000
hivyo kama una idadi 2, kwa mfano, ni kwenda kuja hapa na kusema

461
00:28:17,000 --> 00:28:21,000
kama (x> 0), na ni kwenda kusema ndiyo, hivyo mimi magazeti chanya.

462
00:28:21,000 --> 00:28:25,000
Lakini hata ingawa najua kwamba ni> 0 na si kwenda kuwa 0 au <0

463
00:28:25,000 --> 00:28:29,000
Mimi bado kwenda kufanya ni 0, ni <0,

464
00:28:29,000 --> 00:28:33,000
hivyo mimi nina kweli kwenda ndani ya ikiwa kwamba sikuwa na kwa

465
00:28:33,000 --> 00:28:38,000
kwa sababu tayari najua kwamba si kwenda kukidhi yoyote ya masharti hayo.

466
00:28:38,000 --> 00:28:41,000
Naweza kutumia kama, mwingine kama, mwingine taarifa.

467
00:28:41,000 --> 00:28:45,000
Ni kimsingi anasema kama x = 0 mimi magazeti chanya.

468
00:28:45,000 --> 00:28:48,000
Kama siyo, mimi naenda pia mtihani huu.

469
00:28:48,000 --> 00:28:51,000
Kama ni 2 si mimi naenda kufanya hili.

470
00:28:51,000 --> 00:28:54,000
Kimsingi kama alikuwa x = 2 ungependa kusema

471
00:28:54,000 --> 00:28:57,000
kama (x> 0), ndiyo, hivyo magazeti hii.

472
00:28:57,000 --> 00:29:00,000
Sasa kwa kuwa najua kwamba ni> 0 na kwamba ameridhika kwanza ikiwa

473
00:29:00,000 --> 00:29:02,000
Mimi si hata kwenda kukimbia hii code.

474
00:29:02,000 --> 00:29:09,000
code anaendesha kwa kasi, kwa kweli, mara 3 kwa kasi kama wewe kutumia hii.

475
00:29:09,000 --> 00:29:11,000
Sisi pia kujifunza kuhusu na na au.

476
00:29:11,000 --> 00:29:15,000
Sitakuja kupitia hii kwa sababu Lexi tayari kuongelea kuhusu wao.

477
00:29:15,000 --> 00:29:17,000
Ni tu && na | | operator.

478
00:29:17,000 --> 00:29:21,000
>> Kitu tu nitasema ni kuwa makini wakati una hali ya 3.

479
00:29:21,000 --> 00:29:24,000
Matumizi mabano kwa sababu ni utata sana wakati una hali

480
00:29:24,000 --> 00:29:27,000
na mwingine mmoja au mwingine.

481
00:29:27,000 --> 00:29:30,000
Matumizi ya mabano tu kuwa na uhakika kwamba hali yako ya kufanya maana

482
00:29:30,000 --> 00:29:34,000
kwa sababu katika kesi hiyo, kwa mfano, unaweza kufikiria kwamba

483
00:29:34,000 --> 00:29:38,000
inaweza kuwa ni hali ya kwanza na moja au nyingine

484
00:29:38,000 --> 00:29:41,000
au hali ya 2 pamoja na katika

485
00:29:41,000 --> 00:29:45,000
au moja ya tatu, hivyo tu kuwa makini.

486
00:29:45,000 --> 00:29:48,000
Na hatimaye, kuongelea swichi.

487
00:29:48,000 --> 00:29:53,000
kubadili ni muhimu sana wakati una kutofautiana.

488
00:29:53,000 --> 00:29:55,000
Hebu kusema kwamba una variable kama n

489
00:29:55,000 --> 00:29:59,000
ambayo inaweza kuwa 0, 1, au 2, na kwa kila kesi hizo

490
00:29:59,000 --> 00:30:01,000
utaenda kufanya kazi.

491
00:30:01,000 --> 00:30:04,000
Unaweza kusema kubadili variable, na inaonyesha kuwa

492
00:30:04,000 --> 00:30:08,000
thamani basi ni kama value1 mimi naenda kufanya hii,

493
00:30:08,000 --> 00:30:12,000
na kisha mimi kuvunja, ambayo ina maana mimi si kwenda kuangalia yoyote ya kesi nyingine

494
00:30:12,000 --> 00:30:15,000
kwa sababu sisi tayari kuridhika kwamba kesi

495
00:30:15,000 --> 00:30:20,000
na kisha value2 na kadhalika, na mimi pia unaweza kuwa na kubadili default.

496
00:30:20,000 --> 00:30:24,000
Hiyo ina maana kama hana kukidhi yoyote ya kesi kuwa nilikuwa

497
00:30:24,000 --> 00:30:29,000
kwamba mimi naenda kufanya kitu kingine, lakini hiyo ni hiari.

498
00:30:29,000 --> 00:30:36,000
Hayo ni yote kwa ajili yangu. Sasa hebu kuwa Tommy.

499
00:30:36,000 --> 00:30:41,000
Haki zote, hii ni kwenda kuwa Wiki ya 3-ish.

500
00:30:41,000 --> 00:30:45,000
Hizi ni baadhi ya mada tutaweza kuwa kifuniko, crypto, upeo arrays,, nakadhalika.

501
00:30:45,000 --> 00:30:49,000
Tu neno ya haraka juu ya crypto. Sisi siyo kwenda nyundo hii nyumbani.

502
00:30:49,000 --> 00:30:52,000
>> Sisi alifanya hivyo katika pset 2, lakini kwa jaribio kuhakikisha kujua tofauti

503
00:30:52,000 --> 00:30:54,000
kati ya cipher Kaisari na cipher Vigenère,

504
00:30:54,000 --> 00:30:57,000
jinsi ya wale wote kazi ciphers na kile ni kama encrypt

505
00:30:57,000 --> 00:30:59,000
na decrypt maandishi kwa kutumia ciphers wale 2.

506
00:30:59,000 --> 00:31:03,000
Kumbuka, cipher Kaisari tu rotates kila tabia kwa kiasi sawa,

507
00:31:03,000 --> 00:31:06,000
kuhakikisha Mod kwa idadi ya herufi katika alfabeti.

508
00:31:06,000 --> 00:31:09,000
Na cipher Vigenère, kwa upande mwingine, rotates kila tabia

509
00:31:09,000 --> 00:31:12,000
kwa kiasi tofauti, hivyo badala ya kusema

510
00:31:12,000 --> 00:31:15,000
kuzungushwa tabia kila na Vigenère 3 utazunguka kila tabia

511
00:31:15,000 --> 00:31:17,000
kwa kiasi tofauti kutegemea Keyword baadhi

512
00:31:17,000 --> 00:31:20,000
ambapo kila barua katika Keyword inawakilisha baadhi kiasi tofauti

513
00:31:20,000 --> 00:31:26,000
kwa mzunguko Nakala wazi kwa.

514
00:31:26,000 --> 00:31:28,000
Hebu kwanza majadiliano kuhusu wigo kutofautiana.

515
00:31:28,000 --> 00:31:30,000
Kuna 2 aina tofauti ya vigezo.

516
00:31:30,000 --> 00:31:33,000
Tuna vigezo mitaa, na haya ni kwenda kuelezwa

517
00:31:33,000 --> 00:31:36,000
nje ya kuu au nje ya kazi yoyote au kuzuia,

518
00:31:36,000 --> 00:31:39,000
na haya yatakuwa kupatikana popote katika programu yako.

519
00:31:39,000 --> 00:31:41,000
Kama una kazi na katika kazi kwamba ni kitanzi wakati

520
00:31:41,000 --> 00:31:44,000
kubwa variable kimataifa ni kupatikana kila mahali.

521
00:31:44,000 --> 00:31:48,000
variable mitaa, kwa upande mwingine, ni scoped mahali ambapo ni defined.

522
00:31:48,000 --> 00:31:53,000
>> Kama una kazi hapa, kwa mfano, tuna hii g kazi,

523
00:31:53,000 --> 00:31:56,000
na ndani ya g kuna kutofautiana hapa aitwaye y,

524
00:31:56,000 --> 00:31:58,000
na hiyo ina maana kwamba hii ni variable mitaa.

525
00:31:58,000 --> 00:32:00,000
Hata ingawa variable hii inaitwa y

526
00:32:00,000 --> 00:32:03,000
na kutofautiana hii inaitwa y kazi hizi 2

527
00:32:03,000 --> 00:32:06,000
hawana wazo nini kila mmoja vigezo mitaa ni.

528
00:32:06,000 --> 00:32:10,000
Kwa upande mwingine, hapa tunasema int x = 5,

529
00:32:10,000 --> 00:32:12,000
na hii ni nje ya upeo wa kazi yoyote.

530
00:32:12,000 --> 00:32:16,000
Ni nje ya upeo wa kuu, hivyo hii ni variable kimataifa.

531
00:32:16,000 --> 00:32:20,000
Hiyo ina maana kwamba ndani ya kazi hizi 2 wakati mimi kusema x - au x + +

532
00:32:20,000 --> 00:32:26,000
Mimi nina kupata x huo ambapo hii y na hii ni tofauti y vigezo.

533
00:32:26,000 --> 00:32:30,000
Hiyo ni tofauti kati ya variable kimataifa na variable mitaa.

534
00:32:30,000 --> 00:32:33,000
Mbali kama design ni wasiwasi, wakati mwingine ni pengine wazo bora

535
00:32:33,000 --> 00:32:37,000
kuweka vigezo mitaa wakati wowote wewe waweza

536
00:32:37,000 --> 00:32:39,000
tangu akiwa rundo la vigezo kimataifa inaweza kupata kweli utata.

537
00:32:39,000 --> 00:32:42,000
Kama wewe kuwa na rundo la utendaji wote kubadilisha kitu kimoja

538
00:32:42,000 --> 00:32:45,000
unaweza kusahau nini kama kazi hii ajali hugeuza hii ya kimataifa,

539
00:32:45,000 --> 00:32:47,000
na hii kazi nyingine hajui kuhusu hilo,

540
00:32:47,000 --> 00:32:50,000
na haina kupata pretty utata kama wewe kupata zaidi code.

541
00:32:50,000 --> 00:32:53,000
Kuweka vigezo mitaa wakati wowote wewe waweza

542
00:32:53,000 --> 00:32:56,000
ni nzuri tu design.

543
00:32:56,000 --> 00:33:00,000
Arrays, kumbuka, ni tu orodha ya mambo ya aina moja.

544
00:33:00,000 --> 00:33:04,000
Ndani ya CI haiwezi kuwa na orodha kama 1, 2.0, hello.

545
00:33:04,000 --> 00:33:06,000
Sisi tu hawezi kufanya hivyo.

546
00:33:06,000 --> 00:33:11,000
>> Wakati sisi kutangaza safu katika C wote wa mambo kuwa ya aina moja.

547
00:33:11,000 --> 00:33:14,000
Hapa nina safu ya integers 3.

548
00:33:14,000 --> 00:33:18,000
Hapa nina urefu wa safu, lakini kama mimi tu kutangaza katika syntax hii

549
00:33:18,000 --> 00:33:21,000
ambapo mimi bayana nini wote wa mambo ni mimi si kitaalam haja hii 3.

550
00:33:21,000 --> 00:33:25,000
compiler ni smart kutosha kufikiri jinsi kubwa safu lazima.

551
00:33:25,000 --> 00:33:28,000
Sasa wakati nataka kupata au kuweka thamani ya safu

552
00:33:28,000 --> 00:33:30,000
hii ni syntax ya kufanya hivyo.

553
00:33:30,000 --> 00:33:33,000
Hii kwa kweli kurekebisha kipengele pili wa safu kwa sababu, kumbuka,

554
00:33:33,000 --> 00:33:36,000
hesabu kuanza saa 0, si katika 1.

555
00:33:36,000 --> 00:33:42,000
Kama mimi nataka kusoma kwamba thamani siwezi kusema kitu kama int x = array [1].

556
00:33:42,000 --> 00:33:44,000
Au kama nataka kuweka kwamba thamani, kama mimi kufanya hapa,

557
00:33:44,000 --> 00:33:47,000
Naweza kusema safu [1] = 4.

558
00:33:47,000 --> 00:33:50,000
Kwamba wakati wa kupata vipengele na index yao

559
00:33:50,000 --> 00:33:52,000
au nafasi zao au ambapo wao ni katika safu,

560
00:33:52,000 --> 00:33:57,000
na tangazo ambalo kuanza saa 0.

561
00:33:57,000 --> 00:34:00,000
Tunaweza pia kuwa arrays ya arrays,

562
00:34:00,000 --> 00:34:03,000
na hii inaitwa safu multi-dimensional.

563
00:34:03,000 --> 00:34:05,000
Wakati tuna safu multi-dimensional

564
00:34:05,000 --> 00:34:07,000
hiyo ina maana tunaweza kuwa na kitu kama safu na nguzo,

565
00:34:07,000 --> 00:34:11,000
na hii ni moja ya njia ya visualizing hii au kufikiri juu yake.

566
00:34:11,000 --> 00:34:14,000
Wakati nina safu multi-dimensional kwamba maana Mimi naenda kuanza wanaohitaji

567
00:34:14,000 --> 00:34:17,000
zaidi ya 1 index kwa sababu kama mimi na gridi ya taifa

568
00:34:17,000 --> 00:34:19,000
kusema tu kile mstari uko hautupatii idadi.

569
00:34:19,000 --> 00:34:22,000
Hiyo ni kweli tu kwenda kutupa orodha ya namba.

570
00:34:22,000 --> 00:34:25,000
Hebu sema nina hii safu hapa.

571
00:34:25,000 --> 00:34:30,000
Nina safu kuitwa gridi ya taifa, na mimi kusema ni safu ya 2 na 3 nguzo,

572
00:34:30,000 --> 00:34:32,000
na hivyo hii ni njia mojawapo ya visualizing yake.

573
00:34:32,000 --> 00:34:37,000
Wakati mimi kusema nataka kupata kipengele katika [1] [2]

574
00:34:37,000 --> 00:34:41,000
hiyo ina maana kwamba kwa sababu hizi ni safu ya kwanza na kisha nguzo

575
00:34:41,000 --> 00:34:44,000
Mimi naenda kuruka kwa mstari 1 tangu mimi alisema 1.

576
00:34:44,000 --> 00:34:49,000
>> Kisha mimi naenda kuja hapa kwa safu 2, na mimi nina kwenda kupata thamani 6.

577
00:34:49,000 --> 00:34:51,000
Mantiki?

578
00:34:51,000 --> 00:34:55,000
Multi-dimensional arrays, kumbuka, ni utaalamu tu safu ya arrays.

579
00:34:55,000 --> 00:34:57,000
Tunaweza kuwa na arrays ya arrays ya arrays.

580
00:34:57,000 --> 00:35:00,000
Tunaweza kuendelea, lakini kwa kweli moja ya njia ya kufikiri juu ya

581
00:35:00,000 --> 00:35:03,000
jinsi hii ni kuwa aliweka nje na nini kinaendelea ni taswira yake

582
00:35:03,000 --> 00:35:09,000
katika gridi ya taifa kama hii.

583
00:35:09,000 --> 00:35:12,000
Wakati sisi kupita arrays kwa kazi, wao wanaenda kuishi

584
00:35:12,000 --> 00:35:16,000
kidogo tofauti kuliko wakati sisi kupita vigezo mara kwa mara kwa kazi

585
00:35:16,000 --> 00:35:18,000
kama kupita int au kuelea.

586
00:35:18,000 --> 00:35:21,000
Wakati sisi kupita katika aina int au Char au yoyote ya data hizi nyingine

587
00:35:21,000 --> 00:35:24,000
sisi tu alichukua kuangalia kama kazi hugeuza

588
00:35:24,000 --> 00:35:28,000
thamani ya variable kwamba kuwa mabadiliko si kwenda kueneza up

589
00:35:28,000 --> 00:35:32,000
kwa kazi wito.

590
00:35:32,000 --> 00:35:35,000
Na safu, kwa upande mwingine, kwamba kitatokea.

591
00:35:35,000 --> 00:35:39,000
Kama mimi kupita katika safu ya kazi baadhi na kazi kwamba mabadiliko ya baadhi ya vipengele,

592
00:35:39,000 --> 00:35:43,000
wakati mimi kurudi hadi kazi ambayo kuitwa ni

593
00:35:43,000 --> 00:35:47,000
safu yangu sasa ni kwenda kuwa tofauti, na msamiati kwa kuwa

594
00:35:47,000 --> 00:35:50,000
arrays ni ni kupita kwa kumbukumbu, kama tutaweza kuona baadaye.

595
00:35:50,000 --> 00:35:53,000
Hii ni kuhusiana na jinsi ya kuyatumia kazi, ambapo haya ya msingi data aina,

596
00:35:53,000 --> 00:35:55,000
kwa upande mwingine, ni kupita kwa thamani.

597
00:35:55,000 --> 00:35:59,000
>> Tunaweza kufikiria kwamba kama kufanya nakala ya variable baadhi na kisha kupita katika nakala.

598
00:35:59,000 --> 00:36:01,000
Haijalishi nini sisi kufanya na variable kwamba.

599
00:36:01,000 --> 00:36:06,000
kazi wito si kuwa na ufahamu kwamba ilikuwa iliyopita.

600
00:36:06,000 --> 00:36:10,000
Arrays ni kidogo tu tofauti katika suala hilo.

601
00:36:10,000 --> 00:36:13,000
Kwa mfano, kama sisi tu nikaona, kuu ni utendaji tu

602
00:36:13,000 --> 00:36:15,000
kwamba wanaweza kuchukua katika hoja 2.

603
00:36:15,000 --> 00:36:20,000
Hoja ya kwanza kwa kazi kubwa ni argc, au idadi ya hoja,

604
00:36:20,000 --> 00:36:23,000
na hoja ya pili inaitwa argv,

605
00:36:23,000 --> 00:36:27,000
na wale ni halisi maadili ya hoja hizo.

606
00:36:27,000 --> 00:36:30,000
Hebu sema nina mpango ujulikanao this.c,

607
00:36:30,000 --> 00:36:34,000
na mimi kusema kufanya hili, na mimi nina kwenda kukimbia hii ifikapo mstari amri.

608
00:36:34,000 --> 00:36:38,000
Sasa kupita katika hoja ya baadhi ya programu yangu iitwayo hii,

609
00:36:38,000 --> 00:36:42,000
Mimi naweza kusema kitu kama /. Hii ni cs 50.

610
00:36:42,000 --> 00:36:45,000
Hii ni nini sisi kufikiria Daudi kufanya kila siku katika terminal.

611
00:36:45,000 --> 00:36:48,000
Lakini sasa kuu kazi ndani ya mpango huo

612
00:36:48,000 --> 00:36:52,000
ina maadili haya, hivyo argc ni 4.

613
00:36:52,000 --> 00:36:56,000
Inaweza kuwa utata kidogo kwa sababu kwa kweli tuko tu kupita katika cs ni 50.

614
00:36:56,000 --> 00:36:58,000
Hiyo tu 3.

615
00:36:58,000 --> 00:37:02,000
Lakini kumbuka kwamba kipengele kwanza ya argv au hoja ya kwanza

616
00:37:02,000 --> 00:37:05,000
ni jina ya kazi yenyewe.

617
00:37:05,000 --> 00:37:07,190
Hivyo hiyo ina maana kwamba tuna mambo 4 hapa,

618
00:37:07,190 --> 00:37:10,530
na kipengele kwanza ni kwenda kuwa. / huu.

619
00:37:10,530 --> 00:37:12,970
Na hii itakuwa kuwakilishwa kama kamba.

620
00:37:12,970 --> 00:37:18,590
Kisha mambo iliyobaki ni nini sisi typed katika baada ya jina la mpango.

621
00:37:18,590 --> 00:37:22,720
Hivyo tu kama kando, kama sisi pengine aliona katika pset 2,

622
00:37:22,720 --> 00:37:28,780
kukumbuka kwamba string 50 ni ≠ 50 integer.

623
00:37:28,780 --> 00:37:32,520
Hivyo hatuwezi kusema kitu kama, 'int x = argv 3.'

624
00:37:32,520 --> 00:37:36,470
>> Hiyo tu si kwenda kufanya maana, kwa sababu hii ni kamba, na hii ni integer.

625
00:37:36,470 --> 00:37:38,510
Hivyo kama unataka kubadilisha kati ya 2, kumbuka, tunakwenda

626
00:37:38,510 --> 00:37:40,810
kuwa kazi hii uchawi kuitwa atoi.

627
00:37:40,810 --> 00:37:46,270
Hii inachukua kamba na anarudi integer kuwakilishwa ndani ya kamba hiyo.

628
00:37:46,270 --> 00:37:48,360
Basi hiyo ni kosa rahisi kufanya juu ya chemsha bongo,

629
00:37:48,360 --> 00:37:51,590
tu kufikiri kwamba hii itakuwa moja kwa moja kuwa na aina sahihi.

630
00:37:51,590 --> 00:37:53,860
Lakini tu kujua kwamba hawa daima kuwa masharti

631
00:37:53,860 --> 00:38:00,920
hata kama kamba tu ina integer au tabia au kuelea.

632
00:38:00,920 --> 00:38:03,380
Hivyo sasa hebu majadiliano kuhusu mbio wakati.

633
00:38:03,380 --> 00:38:06,700
Wakati tuna hizi algorithms wote kufanya mambo haya yote mambo,

634
00:38:06,700 --> 00:38:11,580
inakuwa muhimu kweli kweli kwa kuuliza swali, "Ni kwa muda gani wao kuchukua?"

635
00:38:11,580 --> 00:38:15,500
Sisi kuwakilisha kwamba pamoja na kitu kinachoitwa asymptotic nukuu.

636
00:38:15,500 --> 00:38:18,430
Hivyo hii ina maana kwamba - vizuri, hebu sema sisi kutoa algorithm wetu

637
00:38:18,430 --> 00:38:20,840
baadhi ya pembejeo kweli, kweli, kweli ni kubwa.

638
00:38:20,840 --> 00:38:23,840
Sisi nataka kuuliza swali, "Ni kwa muda gani ni kwenda kuchukua?

639
00:38:23,840 --> 00:38:26,370
Wangapi hatua itachukua algorithm yetu ya kuendesha

640
00:38:26,370 --> 00:38:29,980
kama kazi ya kawaida ya pembejeo? "

641
00:38:29,980 --> 00:38:33,080
Hivyo njia ya kwanza tunaweza kuelezea kukimbia wakati ni pamoja na kubwa O.

642
00:38:33,080 --> 00:38:35,380
Na hii ni yetu mbaya zaidi kesi mbio wakati.

643
00:38:35,380 --> 00:38:38,590
Hivyo kama tunataka kutatua safu, na sisi kutoa kompyuta yetu safu

644
00:38:38,590 --> 00:38:41,000
kwamba katika utaratibu wa kushuka wakati ni lazima kuwa ili wakipanda,

645
00:38:41,000 --> 00:38:43,130
ambayo inaenda kuwa kesi mbaya.

646
00:38:43,130 --> 00:38:49,800
Hii ni juu yetu amefungwa katika upeo wa urefu wa muda algorithm yetu itachukua.

647
00:38:49,800 --> 00:38:54,740
Kwa upande mwingine, hii Ω ni kwenda kuelezea bora kesi mbio wakati.

648
00:38:54,740 --> 00:38:58,210
Hivyo kama sisi kutoa safu tayari kwa sorted algorithm kuchagua,

649
00:38:58,210 --> 00:39:00,940
jinsi itachukua muda mrefu kwa aina yake?

650
00:39:00,940 --> 00:39:06,610
Na hili, basi, inaeleza chini amefungwa kwenye mbio wakati.

651
00:39:06,610 --> 00:39:10,980
Hivyo hapa ni baadhi tu ya maneno kwamba kueleza baadhi ya kawaida mara mbio.

652
00:39:10,980 --> 00:39:13,120
Hizi ni katika wakipanda ili.

653
00:39:13,120 --> 00:39:16,060
muda wa kasi mbio tuna inaitwa mara kwa mara.

654
00:39:16,060 --> 00:39:19,800
>> Hiyo ina maana bila kujali jinsi wengi vipengele sisi kutoa kompyuta yetu,

655
00:39:19,800 --> 00:39:22,280
hakuna jambo gani kubwa safu yetu ni, kuchagua ni

656
00:39:22,280 --> 00:39:26,510
au kufanya chochote tuko kufanya na safu daima kuchukua kiasi hicho hicho.

657
00:39:26,510 --> 00:39:30,270
Hivyo tunaweza kuwakilisha kwamba tu kwa 1, ambayo ni mara kwa mara.

658
00:39:30,270 --> 00:39:32,410
Sisi pia inaonekana katika wakati logarithmic kukimbia.

659
00:39:32,410 --> 00:39:34,800
Hivyo kitu kama tafuta binary ni logarithmic,

660
00:39:34,800 --> 00:39:37,140
ambapo sisi kukata tatizo katika kila nusu wakati

661
00:39:37,140 --> 00:39:40,970
na kisha mambo kupata tu juu kutoka huko.

662
00:39:40,970 --> 00:39:43,580
Na kama wewe ni milele kuandika O ya algorithm yoyote factorial,

663
00:39:43,580 --> 00:39:47,850
pengine haipaswi kufikiria hili kama siku kazi yako.

664
00:39:47,850 --> 00:39:53,910
Wakati sisi kulinganisha mara mbio ni muhimu kukumbuka mambo haya.

665
00:39:53,910 --> 00:39:57,760
Hivyo kama nina algorithm kwamba O (n), na mtu mwingine

666
00:39:57,760 --> 00:40:03,590
ina algorithm ya O (2n) haya ni kweli asymptotically sawa.

667
00:40:03,590 --> 00:40:06,590
Hivyo kama sisi kufikiria n kuwa idadi kubwa kama eleventy bilioni:

668
00:40:06,590 --> 00:40:13,090
hivyo wakati sisi ni kulinganisha eleventy bilioni kitu kama eleventy bilioni + 3,

669
00:40:13,090 --> 00:40:17,640
ghafla 3 kwamba kweli haina kufanya tofauti kubwa tena.

670
00:40:17,640 --> 00:40:20,980
Hiyo ni kwa nini sisi ni kwenda kuanza kuzingatia mambo haya kuwa sawa.

671
00:40:20,980 --> 00:40:24,220
Hivyo mambo kama constants haya hapa, kuna 2 x hii, au kuongeza 3,

672
00:40:24,220 --> 00:40:27,180
hizi ni baadhi tu ya constants, na haya ni kwenda kuacha up.

673
00:40:27,180 --> 00:40:32,480
Hivyo kwamba ni kwa nini wote 3 ya nyakati hizi kukimbia ni sawa na kusema wao uko O (n).

674
00:40:32,480 --> 00:40:37,490
Vile vile, kama tuna 2 mara kukimbia mwingine, hebu sema O (n + 2n ² ³), tunaweza kuongeza

675
00:40:37,490 --> 00:40:42,070
+ N, + 7, na kisha tuna wakati mwingine kukimbia kwamba tu O (n ³).

676
00:40:42,070 --> 00:40:46,290
tena, hayo ni kitu kimoja kwa sababu hizi - haya si sawa.

677
00:40:46,290 --> 00:40:49,840
Haya ni mambo sawa, pole. Basi hizi ni sawa kwa sababu

678
00:40:49,840 --> 00:40:53,090
hii ³ n ni kwenda kutawala hii ² 2n.

679
00:40:53,090 --> 00:40:59,130
>> Je, ni si kitu kimoja ni kama sisi kukimbia mara kama O (n ³) na O (n ²)

680
00:40:59,130 --> 00:41:02,820
kwa sababu hii ³ n ni kubwa kuliko hii ² n.

681
00:41:02,820 --> 00:41:05,470
Hivyo kama tuna mashujaa, ghafla hii kuanza jambo,

682
00:41:05,470 --> 00:41:08,280
lakini wakati sisi ni tu kushughulika na mambo kama sisi ni hapa juu,

683
00:41:08,280 --> 00:41:12,810
basi si kwenda umuhimu kwa sababu wao ni kwenda tu kuacha shule.

684
00:41:12,810 --> 00:41:16,760
Hebu tuangalie baadhi ya algorithms tumeona hivyo mbali

685
00:41:16,760 --> 00:41:19,260
na majadiliano juu ya kukimbia muda wao.

686
00:41:19,260 --> 00:41:23,850
Njia ya kwanza ya kutafuta namba katika orodha, kuwa tuliona, alikuwa linear tafuta.

687
00:41:23,850 --> 00:41:26,950
Na utekelezaji wa tafuta linear ni super moja kwa moja.

688
00:41:26,950 --> 00:41:30,490
Sisi tu kuwa na orodha, na sisi ni kwenda kuangalia kila moja ya kipengele katika orodha

689
00:41:30,490 --> 00:41:34,260
mpaka sisi kupata idadi sisi ni kuangalia kwa.

690
00:41:34,260 --> 00:41:38,370
Hivyo hiyo ina maana kwamba katika kesi mbaya, hii O (n).

691
00:41:38,370 --> 00:41:40,860
Na hali mbaya hapa inaweza kuwa kama kipengele ni

692
00:41:40,860 --> 00:41:45,710
kipengele mwisho, basi kwa kutumia tafuta linear tuna kuangalia kipengele kila moja

693
00:41:45,710 --> 00:41:50,180
mpaka sisi kupata moja ya mwisho ili kujua kwamba ni kweli katika orodha.

694
00:41:50,180 --> 00:41:52,910
Hatuwezi kutoa tu juu halfway na kusema, "Ni pengine si huko."

695
00:41:52,910 --> 00:41:55,980
Pamoja na tafuta linear tuna kuangalia jambo zima.

696
00:41:55,980 --> 00:41:59,090
bora-kesi mbio wakati, kwa upande mwingine, ni mara kwa mara

697
00:41:59,090 --> 00:42:04,200
kwa sababu katika kesi bora kipengele sisi ni kuangalia kwa ni moja tu ya kwanza katika orodha.

698
00:42:04,200 --> 00:42:08,930
Hivyo ni kwenda kuchukua yetu hasa 1 hatua, bila kujali jinsi kubwa orodha ni

699
00:42:08,930 --> 00:42:12,140
kama sisi ni kuangalia kwa kipengele kwanza kila wakati.

700
00:42:12,140 --> 00:42:15,390
>> Hivyo wakati wewe kutafuta, kumbuka, hauhitaji kwamba orodha yetu sorted.

701
00:42:15,390 --> 00:42:19,430
Kwa sababu tuko tu kwenda kuangalia juu ya kipengele kila moja, na ni kweli haina jambo

702
00:42:19,430 --> 00:42:23,560
utaratibu gani wale vipengele ni in

703
00:42:23,560 --> 00:42:28,110
akili zaidi tafuta algorithm ni kitu kama tafuta binary.

704
00:42:28,110 --> 00:42:31,500
Kumbuka, utekelezaji wa tafuta binary ni wakati wewe kwenda

705
00:42:31,500 --> 00:42:34,320
kushika kuangalia katikati ya orodha.

706
00:42:34,320 --> 00:42:38,000
Na kwa sababu sisi ni kuangalia katikati, sisi zinahitaji kwamba orodha ni Iliyopangwa

707
00:42:38,000 --> 00:42:40,580
au mwingine hatujui ambapo katikati ni, na inabidi kuangalia juu ya

708
00:42:40,580 --> 00:42:44,480
orodha nzima kupata hiyo, na kisha katika hatua hiyo tuko tu kupoteza muda.

709
00:42:44,480 --> 00:42:48,480
Hivyo kama tuna orodha Iliyopangwa na sisi kupata katikati, tunakwenda kulinganisha katikati

710
00:42:48,480 --> 00:42:51,590
kwa kipengele sisi ni kuangalia kwa.

711
00:42:51,590 --> 00:42:54,640
Kama ni ya juu sana, basi tunaweza kusahau nusu haki

712
00:42:54,640 --> 00:42:57,810
kwa sababu tunajua kwamba kama kipengele yetu ni tayari kubwa mno

713
00:42:57,810 --> 00:43:01,080
na kila kitu na haki ya kipengele hiki ni hata ya juu,

714
00:43:01,080 --> 00:43:02,760
basi hatuna haja ya kuangalia humo tena.

715
00:43:02,760 --> 00:43:05,430
Ambapo kwa upande mwingine, ikiwa kipengele yetu ni ndogo mno,

716
00:43:05,430 --> 00:43:08,700
tunajua kila kitu kwa upande wa kushoto wa kipengele kwamba pia ni ndogo mno,

717
00:43:08,700 --> 00:43:11,390
hivyo ni kweli haina maana kufanya kuangalia huko, aidha.

718
00:43:11,390 --> 00:43:15,760
Kwa njia hii, kwa kila hatua na kila wakati sisi kuangalia midpoint ya orodha,

719
00:43:15,760 --> 00:43:19,060
tunakwenda kupunguza tatizo letu katika nusu kwa sababu tunajua ghafla

720
00:43:19,060 --> 00:43:23,040
rundo zima la idadi kwamba hawezi kuwa mmoja sisi ni kuangalia kwa.

721
00:43:23,040 --> 00:43:26,950
>> Katika pseudocode hii bila kuangalia kitu kama hii,

722
00:43:26,950 --> 00:43:30,990
na kwa sababu tuko kukata orodha katika wakati moja kila nusu,

723
00:43:30,990 --> 00:43:34,920
yetu mbaya zaidi kesi kukimbia wakati anaruka kutoka linear logarithmic.

724
00:43:34,920 --> 00:43:39,260
Hivyo ghafla tuna logi-katika hatua ili kupata kipengele katika orodha.

725
00:43:39,260 --> 00:43:42,460
bora-kesi mbio wakati, ingawa, bado ni ya mara kwa mara

726
00:43:42,460 --> 00:43:45,180
kwa sababu sasa, hebu tu kusema kwamba kipengele sisi ni kuangalia kwa ni

727
00:43:45,180 --> 00:43:48,380
daima katikati ya halisi ya orodha ya awali.

728
00:43:48,380 --> 00:43:52,080
Hivyo tunaweza kukua orodha yetu kubwa kama tunataka, lakini kama kipengele sisi ni kuangalia kwa ni katika katikati,

729
00:43:52,080 --> 00:43:54,910
basi ni kwenda tu kuchukua sisi 1 hatua.

730
00:43:54,910 --> 00:44:00,920
Hivyo ndiyo sababu tuko O (logi n) na Ω (1) au mara kwa mara.

731
00:44:00,920 --> 00:44:04,510
Hebu kweli kukimbia tafuta binary katika orodha hii.

732
00:44:04,510 --> 00:44:08,020
Basi hebu kusema kwamba sisi ni kuangalia kwa kipengele 164.

733
00:44:08,020 --> 00:44:11,650
Jambo la kwanza sisi ni kwenda kufanya ni kupata midpoint ya orodha hii.

734
00:44:11,650 --> 00:44:15,060
Ni hivyo tu hutokea kwamba midpoint anaenda kuanguka katika kati ya namba hizi 2,

735
00:44:15,060 --> 00:44:18,960
hivyo hebu tu kiholela kusema, kila wakati midpoint falls kati ya nambari 2,

736
00:44:18,960 --> 00:44:21,150
hebu tu pande zote juu.

737
00:44:21,150 --> 00:44:24,330
Sisi tu haja ya kuhakikisha sisi kufanya hili kila hatua ya njia.

738
00:44:24,330 --> 00:44:29,040
Hivyo sisi ni kwenda pande zote juu, na sisi ni kwenda kusema kwamba 161 ni katikati ya orodha yetu.

739
00:44:29,040 --> 00:44:34,640
Hivyo 161 <164, na kila kipengele ya kushoto ya 161

740
00:44:34,640 --> 00:44:39,120
ni pia <164, hivyo tunajua kwamba si kwenda kutusaidia wakati wote

741
00:44:39,120 --> 00:44:42,690
kuanza kuangalia zaidi ya hapa kwa sababu ya kipengele sisi ni kuangalia kwa hawezi kuwa huko.

742
00:44:42,690 --> 00:44:47,060
Basi nini tunaweza kufanya ni tunaweza kusahau kuhusu nusu nzima ya kushoto ya orodha,

743
00:44:47,060 --> 00:44:51,700
na sasa tu kufikiria na haki ya kuendelea 161.

744
00:44:51,700 --> 00:44:54,050
>> Hivyo tena, hii ni midpoint; hebu tu pande zote juu.

745
00:44:54,050 --> 00:44:56,260
Sasa 175 ni kubwa mno.

746
00:44:56,260 --> 00:44:59,180
Hivyo tunajua si kwenda kutusaidia kuangalia hapa au hapa,

747
00:44:59,180 --> 00:45:06,610
hivyo tunaweza tu kutupa kwamba mbali, na hatimaye tutaweza hit 164.

748
00:45:06,610 --> 00:45:10,560
Maswali yoyote juu ya kutafuta binary?

749
00:45:10,560 --> 00:45:14,180
Hebu hoja juu ya kutafuta njia ya kutoka orodha tayari-sorted

750
00:45:14,180 --> 00:45:17,660
kwa kweli kuchukua orodha ya namba ili yeyote

751
00:45:17,660 --> 00:45:20,960
na kufanya kwamba orodha katika wakipanda ili.

752
00:45:20,960 --> 00:45:24,060
algorithm kwanza tuliyoyaangalia ilikuwa inaitwa Bubble aina.

753
00:45:24,060 --> 00:45:27,300
Na hii itakuwa rahisi ya algorithms tuliona.

754
00:45:27,300 --> 00:45:32,970
Bubble aina anasema kwamba wakati wowote ndani ya vipengele 2 orodha ni nje ya mahali,

755
00:45:32,970 --> 00:45:36,500
maana kuna idadi kubwa ya kushoto ya idadi ya chini,

756
00:45:36,500 --> 00:45:40,190
kisha tunakwenda byta yao, kwa sababu hiyo ina maana kwamba orodha itakuwa

757
00:45:40,190 --> 00:45:42,860
"Zaidi sorted" kuliko ilivyokuwa kabla.

758
00:45:42,860 --> 00:45:45,180
Na sisi ni kwenda tu kuendelea na mchakato huu tena na tena na tena

759
00:45:45,180 --> 00:45:52,100
mpaka hatimaye aina ya mambo ya Bubble mahali wao sahihi na tuna orodha Iliyopangwa.

760
00:45:52,100 --> 00:45:57,230
>> wakati kukimbia ya hii ni kwenda kuwa O (n ²). Kwa nini?

761
00:45:57,230 --> 00:46:00,370
Naam, kwa sababu katika hali mbaya, sisi ni kwenda kuchukua kila kipengele, na

762
00:46:00,370 --> 00:46:04,570
tunakwenda kuishia kulinganisha na kipengele kila nyingine katika orodha.

763
00:46:04,570 --> 00:46:08,030
Lakini katika kesi bora, tuna orodha tayari sorted, Bubble aina ya

764
00:46:08,030 --> 00:46:12,230
kwenda tu kupitia mara moja, kusema "Nope sikuweza kufanya swaps yoyote., hivyo mimi nina kufanyika."

765
00:46:12,230 --> 00:46:17,410
Hivyo tuna bora kesi mbio wakati wa Ω (n).

766
00:46:17,410 --> 00:46:20,680
Hebu kukimbia Bubble aina juu ya orodha.

767
00:46:20,680 --> 00:46:23,560
Au kwanza, hebu tu kuangalia pseudocode kweli baadhi ya haraka.

768
00:46:23,560 --> 00:46:28,160
Tunataka kusema tunataka kuweka wimbo wa, katika kila iteration ya kitanzi,

769
00:46:28,160 --> 00:46:32,190
kuweka wimbo wa kama au sisi iliyopita mambo yoyote.

770
00:46:32,190 --> 00:46:37,610
Hivyo sababu ya kuwa ni, sisi ni kwenda kuacha wakati sisi si swapped mambo yoyote.

771
00:46:37,610 --> 00:46:41,980
Hivyo wakati wa kuanza kwa kitanzi yetu sisi si swapped kitu chochote, hivyo tutaweza kusema kwamba uongo.

772
00:46:41,980 --> 00:46:47,170
Sasa, sisi ni kwenda kupitia orodha na kulinganisha kipengele i kwa kipengele i + 1

773
00:46:47,170 --> 00:46:50,310
na kama ni suala kwamba kuna idadi kubwa ya kushoto ya idadi ndogo,

774
00:46:50,310 --> 00:46:52,310
basi sisi ni kwenda tu wabadilishane yao.

775
00:46:52,310 --> 00:46:54,490
>> Na kisha sisi ni kwenda kukumbuka kwamba sisi swapped kipengele.

776
00:46:54,490 --> 00:46:58,900
Hiyo ina maana kwamba tunahitaji kwenda kupitia orodha angalau 1 zaidi wakati

777
00:46:58,900 --> 00:47:02,160
kwa sababu hali ambayo sisi kusimamishwa ni wakati orodha nzima tayari Iliyopangwa,

778
00:47:02,160 --> 00:47:04,890
maana sisi si alifanya swaps yoyote.

779
00:47:04,890 --> 00:47:09,960
Hivyo ndiyo sababu hali yetu chini hapa ni 'wakati baadhi ya vipengele wamekuwa swapped.'

780
00:47:09,960 --> 00:47:13,720
Hivyo sasa hebu tu kuangalia hii mbio juu ya orodha.

781
00:47:13,720 --> 00:47:16,640
Nina orodha 5,0,1,6,4.

782
00:47:16,640 --> 00:47:19,850
Bubble aina ni kwenda kuanza njia yote katika kushoto, na ni kwenda kulinganisha

783
00:47:19,850 --> 00:47:24,700
vipengele i, hivyo 0 kwa i + 1, ambayo ni kipengele 1.

784
00:47:24,700 --> 00:47:29,020
Ni kwenda kusema, vizuri 5> 0, lakini hivi sasa ni 5 wa kushoto,

785
00:47:29,020 --> 00:47:32,500
hivyo nahitaji wabadilishane 5 na 0.

786
00:47:32,500 --> 00:47:35,470
Wakati mimi byta yao, ghafla mimi kupata hii orodha tofauti.

787
00:47:35,470 --> 00:47:38,260
Sasa 5> 1, hivyo tunakwenda byta yao.

788
00:47:38,260 --> 00:47:42,160
5 si> 6, hivyo hatuna haja ya kufanya kitu chochote hapa.

789
00:47:42,160 --> 00:47:46,690
Lakini 6> 4, hivyo tunahitaji wabadilishane.

790
00:47:46,690 --> 00:47:49,740
Tena, sisi haja ya kuendesha kupitia orodha nzima ili hatimaye kugundua

791
00:47:49,740 --> 00:47:52,330
kwamba hizi ni nje ya utaratibu; sisi byta yao,

792
00:47:52,330 --> 00:47:57,120
na katika hatua hii tunahitaji kukimbia kupitia orodha 1 zaidi wakati

793
00:47:57,120 --> 00:48:05,390
kuhakikisha kwamba kila kitu katika utaratibu wake, na katika aina hii kumweka Bubble ina kumaliza.

794
00:48:05,390 --> 00:48:10,720
algorithm mbalimbali kwa ajili ya kuchukua baadhi ya vipengele na kuchagua yao ni uteuzi aina.

795
00:48:10,720 --> 00:48:15,740
Dhana ya aina uteuzi ni kwamba sisi ni kwenda kujenga sehemu ya orodha Iliyopangwa

796
00:48:15,740 --> 00:48:18,150
1 kipengele kwa wakati.

797
00:48:18,150 --> 00:48:23,170
>> Na njia tunakwenda kufanya hivyo ni kwa kujenga sehemu ya kushoto ya orodha.

798
00:48:23,170 --> 00:48:27,510
Na kimsingi, kila - juu ya kila hatua, sisi ni kwenda kuchukua kipengele ndogo sisi wameondoka

799
00:48:27,510 --> 00:48:32,310
kwamba haijawahi sorted bado, na tunakwenda hoja hiyo ndani ya sehemu ya kwamba Iliyopangwa.

800
00:48:32,310 --> 00:48:35,850
Hiyo ina maana tunahitaji kuendelea kupata chini ya kipengele zisizochambuliwa

801
00:48:35,850 --> 00:48:40,720
na kisha kuchukua kipengele cha chini na wabadilishane kwa chochote

802
00:48:40,720 --> 00:48:45,090
kushoto-wengi kipengele kwamba si Iliyopangwa.

803
00:48:45,090 --> 00:48:50,890
wakati kukimbia ya hii ni kwenda kuwa O (n ²) kwa sababu katika hali mbaya

804
00:48:50,890 --> 00:48:55,070
tunahitaji kulinganisha kila kipengele moja kwa kila kipengele nyingine.

805
00:48:55,070 --> 00:48:59,250
Kwa sababu sisi ni kusema kwamba kama sisi kuanza saa nusu kushoto wa orodha, tunahitaji

806
00:48:59,250 --> 00:49:02,970
kupitia sehemu nzima haki ya kupata kipengele ndogo.

807
00:49:02,970 --> 00:49:05,430
Na kisha, tena, tunahitaji kwenda zaidi nzima haki ya sehemu na

808
00:49:05,430 --> 00:49:08,210
kuendelea juu ya kwamba zaidi na tena na tena.

809
00:49:08,210 --> 00:49:11,350
Hiyo itakuwa n ². Sisi ni kwenda haja kwa kitanzi ndani ya mwingine kwa kitanzi

810
00:49:11,350 --> 00:49:13,350
ambayo anapendekeza n ².

811
00:49:13,350 --> 00:49:16,530
Katika mawazo bora kesi, hebu sema sisi kuwapa orodha tayari sorted;

812
00:49:16,530 --> 00:49:19,270
sisi kweli si kufanya lolote bora kuliko ² n.

813
00:49:19,270 --> 00:49:21,730
Kwa sababu ya uteuzi aina hana njia ya kujua kwamba

814
00:49:21,730 --> 00:49:25,540
kipengele cha chini ni moja tu mimi kutokea kwa kuwa na kuangalia.

815
00:49:25,540 --> 00:49:28,970
Ni bado mahitaji ya kuhakikisha kwamba hii ni kweli kima cha chini.

816
00:49:28,970 --> 00:49:31,670
>> Na njia pekee ya kuhakikisha kuwa ni kima cha chini, kwa kutumia hii algorithm,

817
00:49:31,670 --> 00:49:34,640
ni kuangalia kipengele kila moja tena.

818
00:49:34,640 --> 00:49:38,420
Hivyo kweli, kama wewe kuwapa - kama wewe kutoa uteuzi aina orodha tayari Iliyopangwa,

819
00:49:38,420 --> 00:49:42,720
si kwenda kufanya lolote bora kuliko kuwapa orodha ambayo si sorted bado.

820
00:49:42,720 --> 00:49:46,320
Kwa njia, kama ni hutokea kwa kuwa kesi kwamba kitu fulani ni O (kitu)

821
00:49:46,320 --> 00:49:50,640
na omega ya kitu fulani, tunaweza kusema tu zaidi succinctly kwamba ni θ ya kitu fulani.

822
00:49:50,640 --> 00:49:52,760
Hivyo kama unaweza kuona kwamba kuja mahali popote, kwamba ni nini maana ya kwamba tu.

823
00:49:52,760 --> 00:49:57,580
>> Kama kitu ni theta ya n ², ni wote O kubwa (n ²) na Ω (n ²).

824
00:49:57,580 --> 00:49:59,790
Hivyo kesi bora na hali mbaya, haina kufanya tofauti,

825
00:49:59,790 --> 00:50:04,400
algorithm ni kwenda kufanya kitu kimoja kila wakati.

826
00:50:04,400 --> 00:50:06,610
Hivyo hii ni nini pseudocode kwa aina uteuzi inaweza kuangalia kama.

827
00:50:06,610 --> 00:50:10,630
Sisi ni kimsingi kwenda kusema kuwa nataka iterate juu ya orodha

828
00:50:10,630 --> 00:50:15,180
kutoka kushoto kwenda kulia, na katika kila iteration ya kitanzi, mimi naenda kwa hoja

829
00:50:15,180 --> 00:50:19,780
kipengele cha chini katika sehemu hii Iliyopangwa ya orodha.

830
00:50:19,780 --> 00:50:23,260
Na mara moja mimi hoja kitu pale, mimi kamwe haja ya kuangalia kipengele kwamba tena.

831
00:50:23,260 --> 00:50:28,600
Kwa sababu kwa haraka kama mimi wabadilishane kipengele katika sehemu ya kushoto ya orodha, ni vyema

832
00:50:28,600 --> 00:50:32,600
kwa sababu sisi ni kufanya kila kitu katika wakipanda ili kwa kutumia minimums.

833
00:50:32,600 --> 00:50:38,740
Hivyo tulisema, sawa, sisi ni katika nafasi ya i, na sisi haja ya kuangalia yote ya mambo ya

834
00:50:38,740 --> 00:50:42,260
na haki ya i ili kupata kiwango cha chini.

835
00:50:42,260 --> 00:50:46,150
Hivyo kwamba maana tunataka kuangalia kutoka i + 1 hadi mwisho wa orodha.

836
00:50:46,150 --> 00:50:51,610
Na sasa, kama kipengele kwamba sasa tuko kuangalia ni chini ya kiwango cha chini yetu hadi sasa,

837
00:50:51,610 --> 00:50:54,190
ambayo, kumbuka, sisi ni mapya mbali kiwango cha chini tu kuwa

838
00:50:54,190 --> 00:50:57,020
chochote kipengele tuko sasa ni saa; mimi itabidi kudhani kwamba kiwango cha chini.

839
00:50:57,020 --> 00:51:00,270
Kama mimi kupata kipengele kwamba ndogo kuliko kwamba, basi mimi nina kwenda kusema, sawa,

840
00:51:00,270 --> 00:51:02,700
vizuri, nimepata cha chini mpya.

841
00:51:02,700 --> 00:51:06,080
Mimi nina kwenda kukumbuka ambapo kima cha chini kwamba alikuwa.

842
00:51:06,080 --> 00:51:09,560
>> Hivyo sasa, mara moja mimi tumeenda kupitia sehemu kwamba haki zisizochambuliwa,

843
00:51:09,560 --> 00:51:16,690
Naweza kusema mimi nina kwenda wabadilishane kipengele cha chini na kipengele kwamba ni katika nafasi ya i.

844
00:51:16,690 --> 00:51:21,100
Hiyo inaenda kujenga orodha yangu, sehemu yangu sorted ya orodha kutoka kushoto kwenda kulia,

845
00:51:21,100 --> 00:51:25,190
na sisi si milele haja ya kuangalia kipengele tena mara moja ni katika sehemu hiyo.

846
00:51:25,190 --> 00:51:27,930
Mara tumekuwa swapped yake.

847
00:51:27,930 --> 00:51:30,260
Basi hebu kukimbia uteuzi aina katika orodha hii.

848
00:51:30,260 --> 00:51:38,220
kipengele bluu hapa ni kwenda kuwa i, na kipengele nyekundu ni kwenda kuwa kipengele cha chini.

849
00:51:38,220 --> 00:51:41,570
Hivyo i kuanza njia yote katika upande wa kushoto wa orodha, hivyo saa 5.

850
00:51:41,570 --> 00:51:44,610
Sasa tunahitaji kupata chini zisizochambuliwa kipengele.

851
00:51:44,610 --> 00:51:49,480
Hivyo tunasema 0 <5, hivyo ni kiwango cha chini 0 yangu mpya.

852
00:51:49,480 --> 00:51:53,820
>> Lakini siwezi kuacha hapo, kwa sababu hata kama tunaweza kutambua kwamba 0 ni ndogo,

853
00:51:53,820 --> 00:51:59,390
tunahitaji kukimbia kwa njia ya kipengele kila nyingine ya orodha ili kuhakikisha.

854
00:51:59,390 --> 00:52:01,760
Hivyo 1 ni kubwa, 6 ni kubwa, 4 ni kubwa.

855
00:52:01,760 --> 00:52:05,850
Hiyo ina maana kwamba baada ya kuangalia mambo haya yote ya, nimekuwa amedhamiria 0 ni ndogo.

856
00:52:05,850 --> 00:52:09,800
Hivyo nina kwenda wabadilishane 5 na 0.

857
00:52:09,800 --> 00:52:15,480
Mara baada ya mimi wabadilishane kwamba, mimi naenda kupata orodha mpya, na mimi kujua kwamba mimi kamwe haja ya kuangalia kwamba 0 tena

858
00:52:15,480 --> 00:52:19,380
sababu mara nimekuwa swapped ni, nimekuwa sorted yake na sisi ni kosa.

859
00:52:19,380 --> 00:52:22,730
Sasa tu hivyo hutokea kwamba kipengele bluu ni tena 5,

860
00:52:22,730 --> 00:52:26,030
na sisi haja ya kuangalia 1, 6 na 4 kuamua kwamba 1

861
00:52:26,030 --> 00:52:31,520
ni ndogo kuliko kima cha chini ya kipengele, hivyo tutaweza wabadilishane 1 na 5.

862
00:52:31,520 --> 00:52:36,890
Tena, sisi haja ya kuangalia - kulinganisha 5-6 na 4,

863
00:52:36,890 --> 00:52:39,830
na sisi ni kwenda wabadilishane 4 na 5, na hatimaye, kulinganisha

864
00:52:39,830 --> 00:52:45,740
wale namba 2 na kubadilishana nao mpaka sisi kupata orodha yetu Iliyopangwa.

865
00:52:45,740 --> 00:52:49,730
Maswali yoyote juu ya aina uteuzi?

866
00:52:49,730 --> 00:52:56,420
Sawa. Hebu hoja na mada ya mwisho hapa, na kwamba ni recursion.

867
00:52:56,420 --> 00:52:59,810
>> Recursion, kumbuka, ni kweli hii meta kitu ambapo kazi

868
00:52:59,810 --> 00:53:02,740
kurudia wito yenyewe.

869
00:53:02,740 --> 00:53:05,620
Hivyo katika baadhi ya uhakika, wakati fuction yetu ni kurudia wito yenyewe,

870
00:53:05,620 --> 00:53:10,100
kuna haja ya kuwa baadhi uhakika ambayo sisi kuacha wito wenyewe.

871
00:53:10,100 --> 00:53:13,670
Kwa sababu kama hatuwezi kufanya hivyo, basi tuko tu kwenda kuendelea kufanya hivyo milele,

872
00:53:13,670 --> 00:53:16,660
na mpango wetu ni tu si kwenda kusitisha.

873
00:53:16,660 --> 00:53:19,200
Sisi kuita hali hii kesi ya msingi.

874
00:53:19,200 --> 00:53:22,570
Na kesi ya msingi anasema, badala ya kuita kazi tena,

875
00:53:22,570 --> 00:53:25,330
Mimi tu kwenda na kurudi baadhi ya thamani.

876
00:53:25,330 --> 00:53:28,080
Hivyo mara tumekuwa akarudi thamani, tumekuwa kusimamishwa wito wenyewe,

877
00:53:28,080 --> 00:53:32,550
na wengine wa wito tumekuwa alifanya hivyo mbali unaweza pia kurudi.

878
00:53:32,550 --> 00:53:36,050
kinyume ya kesi ya msingi ni kesi ya kujirudia.

879
00:53:36,050 --> 00:53:39,050
Na hii ni wakati tunataka kufanya mwingine wito kwa kazi ambayo sisi ni sasa in

880
00:53:39,050 --> 00:53:44,690
Na sisi pengine, ingawa si mara zote, wanataka kutumia hoja mbalimbali.

881
00:53:44,690 --> 00:53:48,940
>> Hivyo kama sisi kuwa na kazi kuitwa f, na f tu kuitwa kuchukua 1 hoja,

882
00:53:48,940 --> 00:53:52,010
na sisi tu kuweka wito f (1), f (1), f (1), na ni haki hivyo hutokea kwamba

883
00:53:52,010 --> 00:53:56,510
hoja 1 unaingia kesi ya kujirudia, bado tuko kamwe kwenda kuacha.

884
00:53:56,510 --> 00:54:01,620
Hata kama tuna kesi ya msingi, tunahitaji kuhakikisha kuwa hatimaye tunakwenda hit kwamba kesi ya msingi.

885
00:54:01,620 --> 00:54:04,250
Sisi si tu kuendelea kukaa katika kesi hii ya kujirudia.

886
00:54:04,250 --> 00:54:09,870
Kwa ujumla, wakati sisi wenyewe piga, sisi ni pengine anaenda kuwa na hoja tofauti kila wakati.

887
00:54:09,870 --> 00:54:12,700
Hapa ni kweli rahisi kazi ya kujirudia.

888
00:54:12,700 --> 00:54:15,090
Hivyo hii itakuwa compute factorial wa idadi.

889
00:54:15,090 --> 00:54:17,790
Hadi juu hapa tuna msingi wetu kesi.

890
00:54:17,790 --> 00:54:22,330
Katika kesi hiyo n ≤ 1, sisi siyo kwenda kuwaita factorial tena.

891
00:54:22,330 --> 00:54:26,490
Sisi ni kwenda kuacha; tuko tu kwenda na kurudi baadhi ya thamani.

892
00:54:26,490 --> 00:54:30,170
Kama hii si kweli, basi tunakwenda hit kesi yetu ya kujirudia.

893
00:54:30,170 --> 00:54:33,550
Ona hapa kwamba sisi siyo tu wito factorial (n), kwa sababu kwamba bila kuwa na manufaa sana.

894
00:54:33,550 --> 00:54:36,810
Sisi ni kwenda kuwaita factorial ya kitu kingine.

895
00:54:36,810 --> 00:54:40,850
>> Na hivyo unaweza kuona, hatimaye kama sisi kupita kitu factorial (5) au,

896
00:54:40,850 --> 00:54:45,900
sisi ni kwenda kuwaita factorial (4) na kadhalika, na hatimaye tunakwenda hit hii kesi ya msingi.

897
00:54:45,900 --> 00:54:51,730
Hivyo hii inaonekana nzuri. Hebu kuona nini kinatokea wakati sisi kwa kweli kukimbia hii.

898
00:54:51,730 --> 00:54:57,840
Hii ni stack, na hebu kusema kwamba kuu ni kwenda kuwaita kazi hii kwa hoja (4).

899
00:54:57,840 --> 00:55:02,200
Hivyo mara factorial anaona na = 4, factorial nitakuita yenyewe.

900
00:55:02,200 --> 00:55:05,010
Sasa, ghafla, tuna factorial (3).

901
00:55:05,010 --> 00:55:10,780
Hivyo kazi hizi ni kwenda kuendelea kukua mpaka hatimaye sisi hit msingi wetu kesi.

902
00:55:10,780 --> 00:55:17,830
Katika hatua hii, thamani ya kurudi kwa hii ni kurudi (NX thamani ya kurudi kwa hii),

903
00:55:17,830 --> 00:55:21,290
thamani ya kurudi kwa hii ni NX thamani ya kurudi kwa hii.

904
00:55:21,290 --> 00:55:23,290
Hatimaye tunahitaji hit baadhi idadi.

905
00:55:23,290 --> 00:55:26,560
Saa ya juu hapa, tunasema kurudi 1.

906
00:55:26,560 --> 00:55:30,650
Hiyo ina maana kwamba mara sisi kurudi kwamba idadi, tunaweza pop hii mbali stack.

907
00:55:30,650 --> 00:55:36,570
Hivyo hii factorial (1) ni kosa.

908
00:55:36,570 --> 00:55:41,190
Wakati 1 anarudi, hii factorial (1) anarudi, hii kurudi 1.

909
00:55:41,190 --> 00:55:46,910
thamani ya kurudi kwa hii, kumbuka, alikuwa NX thamani ya kurudi kwa hii.

910
00:55:46,910 --> 00:55:50,720
Hivyo ghafla, guy hii anajua kwamba mimi nataka kurudi 2.

911
00:55:50,720 --> 00:55:55,910
>> Hivyo kumbuka, kurudi thamani ya hii ni NX thamani kurudi hapa.

912
00:55:55,910 --> 00:56:01,160
Hivyo sasa tunaweza kusema 3 x 2, na hatimaye, hapa tunaweza kusema

913
00:56:01,160 --> 00:56:04,010
hii ni kwenda tu kuwa 4 x 3 x 2.

914
00:56:04,010 --> 00:56:09,570
Na mara moja anarudi hii, sisi kupata chini ya ndani ya moja ya integer kuu.

915
00:56:09,570 --> 00:56:15,460
Maswali yoyote juu ya recursion?

916
00:56:15,460 --> 00:56:17,090
Wote haki. Hivyo kuna muda zaidi kwa maswali mwishoni,

917
00:56:17,090 --> 00:56:23,360
lakini sasa Joseph itafikia mada iliyobaki.

918
00:56:23,360 --> 00:56:25,590
>> [Joseph Ong] wote wa kulia. Hivyo sasa kwamba tumekuwa aliyesema kuhusu recursions,

919
00:56:25,590 --> 00:56:27,840
hebu majadiliano kidogo kuhusu nini kuchanganya aina ni.

920
00:56:27,840 --> 00:56:31,740
Changanya aina kimsingi ni njia nyingine ya kuchagua orodha ya namba.

921
00:56:31,740 --> 00:56:36,430
Na jinsi kazi ni pamoja na aina kuunganisha una orodha, na nini cha kufanya ni

922
00:56:36,430 --> 00:56:39,120
sisi kusema, hebu kupasuliwa hii katika halves 2.

923
00:56:39,120 --> 00:56:42,750
Tutaweza kwanza kukimbia kuchanganya aina tena juu ya nusu ya kushoto,

924
00:56:42,750 --> 00:56:45,040
kisha tutaweza kukimbia kuunganisha aina ya nusu haki,

925
00:56:45,040 --> 00:56:50,240
na kwamba inatupa sasa halves 2 kwamba wanatenganishwa, na sasa tunakwenda kuchanganya halves wale pamoja.

926
00:56:50,240 --> 00:56:55,010
Ni ngumu kidogo kuona bila mfano, hivyo tutaweza kwenda kupitia hisia na kuona nini kinatokea.

927
00:56:55,010 --> 00:56:59,590
Hivyo kuanza na orodha hii, sisi kupasuliwa ndani halves 2.

928
00:56:59,590 --> 00:57:02,300
Sisi kuendesha kuunganisha aina ya nusu ya kushoto ya kwanza.

929
00:57:02,300 --> 00:57:06,660
Basi hiyo ni nusu ya kushoto, na sasa sisi kukimbia nao kwa njia ya orodha hii tena

930
00:57:06,660 --> 00:57:09,800
ambayo anapata kupita katika aina kuunganisha, na kisha sisi kuangalia, tena,

931
00:57:09,800 --> 00:57:13,270
katika upande wa kushoto wa orodha hii na sisi kukimbia kuchanganya aina juu yake.

932
00:57:13,270 --> 00:57:15,880
Sasa, sisi kupata chini ya orodha ya namba 2,

933
00:57:15,880 --> 00:57:19,010
na sasa nusu kushoto ni 1 tu kipengele muda mrefu, na hatuwezi

934
00:57:19,010 --> 00:57:23,380
kupasuliwa orodha hiyo ni 1 tu ya kipengele ndani ya nusu, hivyo sisi tu kusema, mara tuna 50,

935
00:57:23,380 --> 00:57:26,400
ambayo ni 1 tu kipengele, ni tayari Iliyopangwa.

936
00:57:26,400 --> 00:57:29,860
>> Mara sisi ni kosa na kwamba, tunaweza kuona kwamba tunaweza

937
00:57:29,860 --> 00:57:32,230
kuhamia kwenye nusu wa kulia wa orodha hii,

938
00:57:32,230 --> 00:57:36,480
na 3 pia Iliyopangwa, na hivyo kwa sasa kwamba halves wote wa orodha hii ni sorted

939
00:57:36,480 --> 00:57:39,080
tunaweza kujiunga namba hizi nyuma pamoja.

940
00:57:39,080 --> 00:57:45,320
Hivyo sisi kuangalia 50 na 3, 3 ni ndogo kuliko 50, hivyo huenda katika kwanza na kisha huja in 50

941
00:57:45,320 --> 00:57:49,340
Sasa, kwamba ni kosa; sisi kurudi nyuma hadi kuwa orodha na aina ni haki nusu.

942
00:57:49,340 --> 00:57:52,440
42 ni ya mwenyewe idadi, hivyo ni tayari Iliyopangwa.

943
00:57:52,440 --> 00:57:57,850
Hivyo sasa sisi kulinganisha haya 2 na 3 ni ndogo kuliko 42, hivyo kwamba anapata kuweka kwanza,

944
00:57:57,850 --> 00:58:02,340
sasa 42 anapata kuweka katika, na 50 anapata kuweka in

945
00:58:02,340 --> 00:58:07,220
Sasa, kwamba ni vyema, sisi kwenda njia yote nyuma juu, 1337 na 15.

946
00:58:07,220 --> 00:58:14,560
Naam, sisi sasa kuangalia nusu ya kushoto ya orodha hii; 1337 ni kwa yenyewe hivyo ni sorted na sawa na 15.

947
00:58:14,560 --> 00:58:19,020
Hivyo sasa sisi kuchanganya namba hizi 2 kutatua kwamba orodha ya awali, 15 <1337,

948
00:58:19,020 --> 00:58:23,060
hivyo huenda katika kwanza, kisha huenda in 1337

949
00:58:23,060 --> 00:58:26,640
Na sasa sisi sorted halves wote wa orodha ya awali ya juu juu.

950
00:58:26,640 --> 00:58:30,440
Na wote sisi kufanya ni kuchanganya haya.

951
00:58:30,440 --> 00:58:36,890
Sisi kuangalia idadi ya kwanza 2 ya orodha hii, 3 <15, hivyo huenda katika safu ya aina ya kwanza.

952
00:58:36,890 --> 00:58:44,460
15 <42, hivyo huenda in Sasa, 42 <1337, kwamba huenda in

953
00:58:44,460 --> 00:58:51,010
50 <1337, hivyo huenda in Na taarifa kwamba sisi tu alichukua namba 2 mbali ya orodha hii.

954
00:58:51,010 --> 00:58:53,640
Hivyo sisi siyo tu alternating kati ya orodha 2.

955
00:58:53,640 --> 00:58:56,050
Sisi ni kuangalia tu mwanzo, na sisi ni kuchukua kipengele

956
00:58:56,050 --> 00:59:00,270
hiyo ni ndogo na kisha kuweka katika safu yetu.

957
00:59:00,270 --> 00:59:04,080
Sasa tumekuwa ilijiunga halves wote na sisi ni kosa.

958
00:59:04,080 --> 00:59:07,780
>> Maswali yoyote kuhusu kuchanganya aina? Ndiyo?

959
00:59:07,780 --> 00:59:14,190
[Mwanafunzi] Kama ni kugawanyika katika makundi mbalimbali, kwa nini sio wao tu umegawanyika mara moja

960
00:59:14,190 --> 00:59:19,970
na una 3 na 2 katika kundi? [Mapumziko ya unintelligible swali]

961
00:59:19,970 --> 00:59:24,940
Sababu - hivyo swali ni, kwa nini hawawezi sisi tu kuunganisha yao katika hatua ya kwanza baada ya sisi kuwa nao?

962
00:59:24,940 --> 00:59:29,530
sababu tunaweza kufanya hivyo, kuanza saa vipengele kushoto-wengi wa pande zote mbili,

963
00:59:29,530 --> 00:59:33,040
na kisha kuchukua moja ndogo na kuiweka katika, ni kwamba sisi kujua kwamba hawa

964
00:59:33,040 --> 00:59:35,290
orodha ya mtu binafsi ni katika amri Iliyopangwa.

965
00:59:35,290 --> 00:59:37,290
Basi, ikiwa mimi nina kuangalia vipengele kushoto-wengi wa halves wote,

966
00:59:37,290 --> 00:59:40,490
Mimi najua kuwa wao ni kwenda kuwa mambo madogo ya orodha ya wagombea hao.

967
00:59:40,490 --> 00:59:43,930
Hivyo siwezi kuziweka katika maeneo madogo ya kipengele cha orodha hii kubwa.

968
00:59:43,930 --> 00:59:47,810
Kwa upande mwingine, kama mimi kuangalia orodha wale 2 katika ngazi ya pili zaidi ya hapo,

969
00:59:47,810 --> 00:59:51,640
50, 3, 42 1337, na 15, wale si Iliyopangwa.

970
00:59:51,640 --> 00:59:55,770
Hivyo kama mimi kuangalia 50 na 1337, Mimi naenda kuweka 50 katika orodha yangu ya kwanza.

971
00:59:55,770 --> 01:00:00,130
Lakini hiyo si kweli mantiki, kwa sababu ni kipengele 3 ndogo nje ya wale wote.

972
01:00:00,130 --> 01:00:04,390
Hivyo sababu moja tu tunaweza kufanya hatua hii ni kwa sababu ya kuchanganya orodha yetu ni tayari Iliyopangwa.

973
01:00:04,390 --> 01:00:07,010
Ambayo ni kwa nini sisi kupata chini njia yote hadi chini

974
01:00:07,010 --> 01:00:09,800
kwa sababu wakati tuna tu namba moja, unajua kwamba namba moja

975
01:00:09,800 --> 01:00:14,120
katika yenyewe ni tayari orodha Iliyopangwa.

976
01:00:14,120 --> 01:00:19,360
>> Maswali yoyote? Hakuna?

977
01:00:19,360 --> 01:00:24,260
Ugumu? Naam, unaweza kuona kwamba katika kila hatua kuna mwisho idadi,

978
01:00:24,260 --> 01:00:27,590
na tunaweza kugawanya katika orodha nusu logi n nyakati,

979
01:00:27,590 --> 01:00:31,700
ambayo ni ambapo sisi kupata hii n x logi n utata.

980
01:00:31,700 --> 01:00:34,940
Na utaona kesi bora kwa ajili ya aina kuunganisha ni n logi n, na ni haki hivyo hutokea

981
01:00:34,940 --> 01:00:39,340
kwamba hali mbaya, au Ω zaidi ya hapo, ni pia n logi n.

982
01:00:39,340 --> 01:00:42,480
Kitu kukumbuka.

983
01:00:42,480 --> 01:00:45,750
Kusonga, hebu kwenda kwenye faili baadhi super msingi I / O.

984
01:00:45,750 --> 01:00:48,830
Kama inaonekana katika kinyang'anyiro, utasikia taarifa tulikuwa na aina fulani ya mfumo wa

985
01:00:48,830 --> 01:00:51,270
ambapo unaweza kuandika kwenye faili logi kama kusoma kwa njia ya kificho.

986
01:00:51,270 --> 01:00:53,730
Hebu angalia jinsi wewe anaweza kufanya hivyo.

987
01:00:53,730 --> 01:00:57,450
Naam, tuna fprintf, ambayo unaweza kufikiria kama tu printf,

988
01:00:57,450 --> 01:01:01,720
lakini tu uchapishaji na faili badala yake, na hivyo f mwanzoni.

989
01:01:01,720 --> 01:01:07,570
Hii aina ya code hapa juu, kile yake ni, kama unaweza kuwa na kuonekana katika kinyang'anyiro,

990
01:01:07,570 --> 01:01:12,310
unaendelea kwa njia ya uchapishaji yako 2-dimensional safu nje mstari na mstari ni namba ni.

991
01:01:12,310 --> 01:01:17,850
Katika kesi hiyo, printf Prints nje terminal yako au kile tunachoita pato kiwango ya sehemu.

992
01:01:17,850 --> 01:01:22,170
>> Na sasa, katika kesi hii, wote sisi kufanya ni kuchukua nafasi printf na fprintf,

993
01:01:22,170 --> 01:01:26,770
kuwaambia ni nini faili unataka magazeti kwa, na katika kesi hii ni tu Prints hivyo nje faili kwamba

994
01:01:26,770 --> 01:01:32,230
badala ya kuchapa hivyo nje terminal yako.

995
01:01:32,230 --> 01:01:36,500
Naam, basi, kwamba begs swali: wapi sisi kupata aina hii ya faili kutoka, sawa?

996
01:01:36,500 --> 01:01:39,840
Sisi kupita kuingia kwenye hii fuction fprintf lakini sisi hakuwa na wazo ilikotoka.

997
01:01:39,840 --> 01:01:43,980
Naam, mapema katika kanuni, kile tulikuwa ilikuwa hii chunk ya maadili ya zaidi ya hapa,

998
01:01:43,980 --> 01:01:48,340
ambayo kimsingi anasema kuwa wazi faili wito log.txt.

999
01:01:48,340 --> 01:01:53,220
Tunachofanya baada ya kuwa ni sisi kuwa na kuhakikisha kwamba faili ni kweli kufunguliwa kwa mafanikio.

1000
01:01:53,220 --> 01:01:57,070
Hivyo wanaweza kushindwa kwa sababu mbalimbali; huna nafasi ya kutosha kwenye kompyuta yako, kwa mfano.

1001
01:01:57,070 --> 01:01:59,790
Hivyo ni muhimu daima kabla ya kufanya shughuli yoyote na faili

1002
01:01:59,790 --> 01:02:03,300
kwamba sisi kuangalia kama faili kwamba kikafunguliwa mafanikio.

1003
01:02:03,300 --> 01:02:09,330
Hivyo kile kwamba, hiyo ni hoja fopen, vizuri, tunaweza kufungua faili kwa njia nyingi.

1004
01:02:09,330 --> 01:02:13,510
Nini tunaweza kufanya ni, tunaweza kupita w, ambayo ina maana override faili kama exits tayari,

1005
01:02:13,510 --> 01:02:18,070
Tunaweza kupita a, ambayo wao append hadi mwisho wa faili kuu badala ya hayo,

1006
01:02:18,070 --> 01:02:22,730
au tunaweza kutaja r, ambayo ina maana, hebu kufungua faili kama kusoma tu.

1007
01:02:22,730 --> 01:02:24,890
Hivyo kama mpango inajaribu kufanya mabadiliko yoyote ya faili,

1008
01:02:24,890 --> 01:02:30,140
yell kwao na si lazima wao kufanya hivyo.

1009
01:02:30,140 --> 01:02:33,320
Hatimaye, mara sisi ni kosa na faili, kufanyika kufanya shughuli juu yake,

1010
01:02:33,320 --> 01:02:35,860
tunahitaji kuhakikisha sisi karibu faili.

1011
01:02:35,860 --> 01:02:38,830
Na hivyo, mwisho wa programu yako, wewe ni kwenda kupita yao tena

1012
01:02:38,830 --> 01:02:42,120
faili hili kwamba kufunguliwa, na tu kulifunga.

1013
01:02:42,120 --> 01:02:44,650
Hivyo hii ni kitu muhimu kwamba una hakikisha kufanya.

1014
01:02:44,650 --> 01:02:47,180
Hivyo kumbuka unaweza kufungua faili, basi unaweza kuandika kwenye faili,

1015
01:02:47,180 --> 01:02:51,270
kufanya shughuli katika faili, lakini basi una kuifunga faili mwishoni.

1016
01:02:51,270 --> 01:02:53,270
>> Maswali yoyote juu ya faili msingi I / O? Ndiyo?

1017
01:02:53,270 --> 01:02:58,050
[Mwanafunzi swali, unintelligible]

1018
01:02:58,050 --> 01:03:02,480
Haki hapa. Swali ni, ambapo haina faili hii log.txt itaonekana?

1019
01:03:02,480 --> 01:03:07,890
Naam, kama wewe tu kuwapa log.txt, ni inajenga katika saraka ya sawa kama kutekelezwa.

1020
01:03:07,890 --> 01:03:10,500
Hivyo kama you're - >> [Mwanafunzi swali, unintelligible]

1021
01:03:10,500 --> 01:03:18,830
Ndiyo. Katika folder sawa, au katika saraka ya sawa, kama wewe simu yake.

1022
01:03:18,830 --> 01:03:21,400
Sasa kumbukumbu, stack, na chungu.

1023
01:03:21,400 --> 01:03:23,400
Hivyo jinsi ni kumbukumbu zilizowekwa katika kompyuta?

1024
01:03:23,400 --> 01:03:26,270
Naam, unaweza kufikiria kama aina ya kumbukumbu hii block hapa.

1025
01:03:26,270 --> 01:03:30,260
Na katika kumbukumbu tuna nini wito lundo kukwama juu huko, na stack kwamba chini huko.

1026
01:03:30,260 --> 01:03:34,480
Na lundo hukua kushuka na stack kukua zaidi.

1027
01:03:34,480 --> 01:03:38,620
Hivyo kama Tommy zilizotajwa - oh, vizuri, na tuna hizi nyingine segment 4 ambayo mimi itabidi kupata katika pili -

1028
01:03:38,620 --> 01:03:42,890
Kama Tommy alisema mapema, unajua jinsi utendaji wake wanajiita na itana?

1029
01:03:42,890 --> 01:03:44,930
Wao kujenga aina hii ya sura ya stack.

1030
01:03:44,930 --> 01:03:47,360
Naam, kama kuu wito foo, foo anapata kuweka kwenye stack.

1031
01:03:47,360 --> 01:03:52,430
Foo wito bar, bar kupata uliowekwa juu stack, na kwamba anapata kuweka kwenye stack baada.

1032
01:03:52,430 --> 01:03:57,040
Na kama wao kurudi, kila mmoja kupata kuchukuliwa mbali stack.

1033
01:03:57,040 --> 01:04:00,140
Nini kila moja ya maeneo haya na kumbukumbu kushikilia?

1034
01:04:00,140 --> 01:04:03,110
Naam, juu, ambayo ni sehemu ya maandishi, ina programu yenyewe.

1035
01:04:03,110 --> 01:04:06,390
Hivyo code mashine, kwamba ni huko, mara moja wewe kukusanya programu yako.

1036
01:04:06,390 --> 01:04:08,520
Next, yoyote initialized vigezo kimataifa.

1037
01:04:08,520 --> 01:04:12,660
>> Hivyo kuwa na vigezo kimataifa katika mpango wako, na wewe kusema kama, 5 =,

1038
01:04:12,660 --> 01:04:15,260
kwamba anapata kuweka katika sehemu hiyo, na kulia chini ya kwamba,

1039
01:04:15,260 --> 01:04:18,990
una uninitialized data kimataifa, ambayo ni haki int,

1040
01:04:18,990 --> 01:04:20,990
lakini huna kusema ni sawa na kitu chochote.

1041
01:04:20,990 --> 01:04:23,870
Kutambua haya ni ya kimataifa vigezo, hivyo ni nje ya kuu.

1042
01:04:23,870 --> 01:04:28,560
Hivyo hii ina maana ya vigezo yoyote ya kimataifa ambayo ni alitangaza lakini si initialized.

1043
01:04:28,560 --> 01:04:32,310
Basi nini katika chungu? Kumbukumbu zilizotengwa kwa kutumia malloc, ambayo tutaweza kupata katika kidogo.

1044
01:04:32,310 --> 01:04:35,990
Na hatimaye, kwa stack una vigezo yoyote mitaa

1045
01:04:35,990 --> 01:04:39,950
na yoyote kazi unaweza kuwaita yoyote ya vigezo yao.

1046
01:04:39,950 --> 01:04:43,720
Jambo la mwisho, wewe si kweli kuwa kujua vigezo mazingira kufanya,

1047
01:04:43,720 --> 01:04:46,700
lakini wakati wewe kuendesha programu, kuna kitu haihusiani, kama

1048
01:04:46,700 --> 01:04:49,550
hii ni username ya mtu ambaye alikimbia mpango.

1049
01:04:49,550 --> 01:04:51,550
Na kwamba ni kwenda kuwa aina ya chini.

1050
01:04:51,550 --> 01:04:54,540
Katika suala la anwani kumbukumbu, ambayo ni hexadesimoli maadili,

1051
01:04:54,540 --> 01:04:58,170
maadili katika kuanza juu saa 0, na wao kwenda njia yote chini kwa chini.

1052
01:04:58,170 --> 01:05:00,440
Katika kesi hii, kama wewe ni juu ya mfumo wa 32-bit,

1053
01:05:00,440 --> 01:05:05,390
anuani hapo chini ni kwenda kuwa 0x, ikifuatiwa na af, kwa sababu hiyo 32 bits,

1054
01:05:05,390 --> 01:05:10,890
ambayo ni 8 ka, na katika kesi hii 8 ka sambamba na tarakimu hexadesimoli 8.

1055
01:05:10,890 --> 01:05:20,110
Hivyo hapa chini wewe utaenda kuwa, kama, 0xffffff, na huko utaenda kuwa na 0.

1056
01:05:20,110 --> 01:05:23,660
Hivyo kile ni kuyatumia? Baadhi ya unaweza kuwa kufunikwa hii katika kifungu kabla.

1057
01:05:23,660 --> 01:05:26,660
lakini hatukuwa kwenda juu yake katika hotuba, hivyo pointer ni aina tu data

1058
01:05:26,660 --> 01:05:34,030
ambayo maduka, badala ya aina fulani ya thamani kama 50, ni maduka ya anuani ya baadhi ya maeneo katika kumbukumbu.

1059
01:05:34,030 --> 01:05:36,020
Kama kumbukumbu kwamba [unintelligible].

1060
01:05:36,020 --> 01:05:41,120
Hivyo katika kesi hii, kile sisi ni, tuna pointer integer au * int,

1061
01:05:41,120 --> 01:05:46,210
na ina anwani hii hexadesimoli ya 0xDEADBEEF.

1062
01:05:46,210 --> 01:05:50,880
>> Hivyo kile sisi ni, sasa, pointi pointer hii katika baadhi ya maeneo katika kumbukumbu,

1063
01:05:50,880 --> 01:05:56,020
na kwamba tu, thamani 50 ni katika eneo hili kumbukumbu.

1064
01:05:56,020 --> 01:06:01,810
Juu ya mifumo ya baadhi ya 32-bit, juu ya mifumo yote ya 32-bit, kuyatumia kuchukua bits 32 au ka 4.

1065
01:06:01,810 --> 01:06:06,020
Lakini, kwa mfano, juu ya mfumo wa 64-bit, kuyatumia ni 64 bits.

1066
01:06:06,020 --> 01:06:08,040
Basi hiyo ni kitu utasikia wanataka kukumbuka.

1067
01:06:08,040 --> 01:06:12,310
Kadhalika mfumo mwisho-bit, pointer ni mwisho bits mrefu.

1068
01:06:12,310 --> 01:06:17,320
Kuyatumia ni aina ya vigumu Digest bila mambo ya ziada,

1069
01:06:17,320 --> 01:06:20,300
hivyo hebu kupitia mfano wa mgao wa nguvu kumbukumbu.

1070
01:06:20,300 --> 01:06:25,130
Nini nguvu kumbukumbu mgao gani kwa ajili yenu, au kile tunachoita malloc,

1071
01:06:25,130 --> 01:06:29,280
inakuwezesha kutenga baadhi ya aina ya data nje ya kuweka.

1072
01:06:29,280 --> 01:06:31,830
Hivyo data hii ni aina ya kudumu zaidi kwa muda wa mpango.

1073
01:06:31,830 --> 01:06:36,430
Kwa sababu kama wewe kujua, kama wewe kutangaza x ndani ya kazi, na anarudi kwamba kazi,

1074
01:06:36,430 --> 01:06:40,910
hakuna tena wa upatikanaji wa takwimu kwamba alikuwa kuhifadhiwa katika x.

1075
01:06:40,910 --> 01:06:44,420
Nini kuyatumia hebu kufanya ni wao hebu kuhifadhi kumbukumbu maadili au kuhifadhi

1076
01:06:44,420 --> 01:06:46,840
katika sehemu mbalimbali za kumbukumbu, yaani lundo.

1077
01:06:46,840 --> 01:06:49,340
Sasa mara sisi kurudi nje ya kazi, muda mrefu kama tuna pointer

1078
01:06:49,340 --> 01:06:54,960
kwa kuwa mahali katika kumbukumbu, kisha nini tunaweza kufanya ni tunaweza tu kuangalia maadili huko.

1079
01:06:54,960 --> 01:06:58,020
Hebu tuangalie mfano: Hii ni kumbukumbu zetu layout tena.

1080
01:06:58,020 --> 01:07:00,050
Na tuna kazi hii, kuu.

1081
01:07:00,050 --> 01:07:06,870
Kile yake ni - sawa, hivyo ni rahisi, haki -? Int x = 5, kwamba tu kutofautiana juu ya stack katika kuu.

1082
01:07:06,870 --> 01:07:12,450
>> Kwa upande mwingine, sasa sisi kutangaza pointer ambayo inatoa wito giveMeThreeInts kazi.

1083
01:07:12,450 --> 01:07:16,800
Na hivyo sasa sisi kwenda katika kazi hii na sisi kujenga mpya stack frame kwa ajili yake.

1084
01:07:16,800 --> 01:07:20,440
Hata hivyo, katika sura hii stack, sisi kutangaza int * temp,

1085
01:07:20,440 --> 01:07:23,210
ambayo katika mallocs 3 integers kwa ajili yetu.

1086
01:07:23,210 --> 01:07:25,880
Hivyo ukubwa wa int atatupa ngapi ka int hii ni,

1087
01:07:25,880 --> 01:07:29,620
na malloc inatupa kwamba wengi bytes ya nafasi katika lundo.

1088
01:07:29,620 --> 01:07:32,890
Hivyo katika kesi hii, tuna umba nafasi ya kutosha kwa ajili ya integers 3,

1089
01:07:32,890 --> 01:07:36,830
na lundo ni njia ya juu huko, ambayo ni kwa nini nimekuwa inayotolewa ni ya juu juu.

1090
01:07:36,830 --> 01:07:42,900
Mara sisi ni kosa, sisi kurudi hapa juu, una haja tu 3 ints wakarudi,

1091
01:07:42,900 --> 01:07:47,000
na kuirudisha anuani, katika kesi hii juu ambapo kumbukumbu kwamba ni.

1092
01:07:47,000 --> 01:07:51,250
Na sisi kuweka pointer = kubadili, na hadi pale tuna mwingine tu pointer.

1093
01:07:51,250 --> 01:07:54,550
Lakini nini kwamba anarudi kazi ni sifa hapa na kutoweka.

1094
01:07:54,550 --> 01:07:59,250
Hivyo temp kutoweka, lakini sisi bado kudumisha anuani ya ambapo

1095
01:07:59,250 --> 01:08:01,850
wale integers 3 ni ndani ya mains.

1096
01:08:01,850 --> 01:08:06,180
Hivyo katika kuweka hii, kuyatumia ni scoped ndani ya nchi kwa sura sifa,

1097
01:08:06,180 --> 01:08:09,860
lakini kumbukumbu ambayo wao ni katika rejea lundo.

1098
01:08:09,860 --> 01:08:12,190
>> Je, hiyo mantiki?

1099
01:08:12,190 --> 01:08:14,960
[Mwanafunzi] Unaweza kurudia kwamba? >> [Joseph] Ndiyo.

1100
01:08:14,960 --> 01:08:20,270
Hivyo kama mimi kurejea tu kidogo, unaweza kuona kwamba temp zilizotengwa

1101
01:08:20,270 --> 01:08:23,500
baadhi ya kumbukumbu juu ya kujikusanyia huko.

1102
01:08:23,500 --> 01:08:28,680
Hivyo wakati kazi hii, giveMeThreeInts anarudi, hii stack hapa ni kwenda na kutoweka.

1103
01:08:28,680 --> 01:08:35,819
Na kwa hayo yoyote ya vigezo, katika kesi hii, hii pointer zilizotengwa katika sura sifa.

1104
01:08:35,819 --> 01:08:39,649
Hiyo ni kwenda kutoweka, lakini tangu tukirudi temp

1105
01:08:39,649 --> 01:08:46,330
na sisi kuweka pointer = temp, pointer sasa ni yatakuelekeza kumbukumbu hiyo ya mahali kama temp ilikuwa.

1106
01:08:46,330 --> 01:08:50,370
Hivyo sasa, hata kama sisi kupoteza temp, kwamba pointer mitaa,

1107
01:08:50,370 --> 01:08:59,109
sisi bado kurejesha anuani ya kumbukumbu ya nini ilikuwa akizungumzia ndani ya pointer kwamba kutofautiana.

1108
01:08:59,109 --> 01:09:03,740
Maswali? Hiyo inaweza kuwa aina ya mada utata kama wewe hawajaenda juu yake katika sehemu.

1109
01:09:03,740 --> 01:09:09,240
Tunaweza, TF yako dhahiri kwenda juu yake na bila shaka tunaweza kujibu maswali

1110
01:09:09,240 --> 01:09:11,500
mwishoni mwa kikao mapitio kwa hili.

1111
01:09:11,500 --> 01:09:14,220
Lakini hii ni aina ya mada ngumu, na mimi kuwa na mifano zaidi kwamba ni kwenda show up

1112
01:09:14,220 --> 01:09:18,790
kwamba itasaidia kufafanua kile kuyatumia kwa kweli ni.

1113
01:09:18,790 --> 01:09:22,500
>> Katika kesi hiyo, kuyatumia ni sawa na arrays,

1114
01:09:22,500 --> 01:09:25,229
hivyo naweza tu kutumia hii pointer kama kitu kimoja kama safu int.

1115
01:09:25,229 --> 01:09:29,840
Hivyo nina Indexing katika 0, na kubadilisha integer kwanza kwa 1,

1116
01:09:29,840 --> 01:09:39,689
kubadilisha integer pili 2, na 3 kwa 3 integer.

1117
01:09:39,689 --> 01:09:44,210
Hivyo zaidi juu ya kuyatumia. Naam, wanakumbuka Binky.

1118
01:09:44,210 --> 01:09:48,319
Katika kesi hii tumekuwa zilizotengwa pointer, au sisi alitangaza pointer,

1119
01:09:48,319 --> 01:09:52,760
lakini awali, wakati mimi tu alitangaza pointer, siyo akizungumzia popote katika kumbukumbu.

1120
01:09:52,760 --> 01:09:54,930
Ni tu takataka maadili ndani yake.

1121
01:09:54,930 --> 01:09:56,470
Kwa hiyo mimi sina wazo ambapo pointer hii ni akizungumzia.

1122
01:09:56,470 --> 01:10:01,630
Ina anuani ambayo ni haki ya kujazwa 0 na 1 ya awali ambapo ilikuwa alitangaza.

1123
01:10:01,630 --> 01:10:04,810
Mimi siwezi kufanya kitu kwa hii mpaka mimi wito malloc juu yake

1124
01:10:04,810 --> 01:10:08,390
na kisha mimi inanipa nafasi kidogo juu ya lundo ambapo naweza kuweka maadili ndani.

1125
01:10:08,390 --> 01:10:11,980
Kisha tena, sijui nini ndani ya kumbukumbu hii.

1126
01:10:11,980 --> 01:10:16,780
Hivyo kitu ya kwanza mimi kufanya ni kuangalia kama mfumo alikuwa kumbukumbu ya kutosha

1127
01:10:16,780 --> 01:10:20,850
kunipa nyuma 1 integer katika nafasi ya kwanza, ambayo ni kwa nini mimi kufanya hili kuangalia.

1128
01:10:20,850 --> 01:10:25,020
Kama pointer ni null, hiyo ina maana kwamba hakuwa na nafasi ya kutosha au baadhi makosa mengine yalitokea,

1129
01:10:25,020 --> 01:10:26,320
hivyo mimi zinapaswa kuachana na nje ya mpango wangu.

1130
01:10:26,320 --> 01:10:29,400
 Lakini kama ilivyokuwa kufanikiwa, sasa naweza kutumia kwamba pointer

1131
01:10:29,400 --> 01:10:35,020
na yale ambayo * pointer gani ni kinachofuata ambapo anuani ni

1132
01:10:35,020 --> 01:10:38,480
kwa thamani ambapo ni kwamba, na unaweka ni sawa na 1.

1133
01:10:38,480 --> 01:10:41,850
Hivyo zaidi ya hapa, sisi ni kuangalia kama kumbukumbu kwamba kuwepo.

1134
01:10:41,850 --> 01:10:45,380
>> Mara tu kujua ipo, unaweza kuweka ndani yake

1135
01:10:45,380 --> 01:10:50,460
thamani gani unataka kuweka ndani yake; katika kesi hii 1.

1136
01:10:50,460 --> 01:10:53,060
Mara sisi ni kosa na hilo, unahitaji huru kwamba pointer

1137
01:10:53,060 --> 01:10:57,160
sababu tunahitaji kupata nyuma mfumo kwamba kumbukumbu kwamba wewe aliuliza kwa katika nafasi ya kwanza.

1138
01:10:57,160 --> 01:10:59,690
Kwa sababu kompyuta hajui wakati sisi ni kosa kwa hayo.

1139
01:10:59,690 --> 01:11:02,510
Katika kesi hii sisi ni wazi kuwaambia hayo, sawa, sisi ni kosa na kumbukumbu hiyo.

1140
01:11:02,510 --> 01:11:10,780
Kama baadhi ya mchakato mahitaji mengine ni, baadhi ya programu nyingine mahitaji yake, kujisikia huru na kwenda mbele na kuchukua hiyo.

1141
01:11:10,780 --> 01:11:15,110
Nini tunaweza pia kufanya ni tunaweza kupata tu anuani ya vigezo mitaa juu ya kuweka.

1142
01:11:15,110 --> 01:11:19,080
Hivyo int x ni ndani ya sura bainifu wa kuu.

1143
01:11:19,080 --> 01:11:23,060
Na wakati sisi kutumia hii ampersand, hii na operator, kile yake ni

1144
01:11:23,060 --> 01:11:27,310
inachukua x, na x ni baadhi tu ya data katika kumbukumbu, lakini ina anuani.

1145
01:11:27,310 --> 01:11:33,790
Ni ziko mahali fulani. Hivyo kwa wito & x, nini hii haina ni inatupa anuani ya x.

1146
01:11:33,790 --> 01:11:38,430
Kwa kufanya hivyo, sisi ni kufanya pointer uhakika ambapo x ni katika kumbukumbu.

1147
01:11:38,430 --> 01:11:41,710
Sasa sisi tu kufanya kitu kama * x, sisi ni kwenda kupata 5 nyuma.

1148
01:11:41,710 --> 01:11:43,820
Nyota hiyo inaitwa dereferencing yake.

1149
01:11:43,820 --> 01:11:46,640
Wewe kufuata anuani na kupata thamani yake kuhifadhiwa huko.

1150
01:11:51,000 --> 01:11:53,310
>> Maswali yoyote? Ndiyo?

1151
01:11:53,310 --> 01:11:56,500
[Mwanafunzi] Kama huwezi kufanya kitu 3-chongoka, gani bado kukusanya?

1152
01:11:56,500 --> 01:11:59,490
Ndiyo. Kama huwezi kufanya kitu 3-pointer, ni bado kwenda kukusanya,

1153
01:11:59,490 --> 01:12:02,720
lakini Mimi nitawaonyesheani nini kinatokea katika pili, na bila kufanya hivyo,

1154
01:12:02,720 --> 01:12:04,860
kwamba ni nini sisi kuwaita leak kumbukumbu. Wewe si kutoa mfumo

1155
01:12:04,860 --> 01:12:07,850
nyuma kumbukumbu yake, hivyo baada ya muda mpango ni kwenda kujilimbikiza

1156
01:12:07,850 --> 01:12:10,940
kumbukumbu kwamba ni si kutumia, na kitu kingine unaweza kutumia.

1157
01:12:10,940 --> 01:12:15,750
Kama ve milele kuonekana Firefox na kilobytes milioni 1.5 kwenye kompyuta yako,

1158
01:12:15,750 --> 01:12:17,840
katika meneja kazi, kwamba ni nini kinaendelea.

1159
01:12:17,840 --> 01:12:20,760
Una leak kumbukumbu katika mpango kwamba wao siyo kuchukua.

1160
01:12:23,080 --> 01:12:26,240
Hivyo ni jinsi gani pointer arithmetic kazi?

1161
01:12:26,240 --> 01:12:29,480
Naam, pointer arithmetic ni aina ya Indexing kama ndani ya safu.

1162
01:12:29,480 --> 01:12:36,370
Katika kesi hiyo, nina pointer, na nini mimi ni mimi kufanya pointer uhakika kwa kipengele kwanza

1163
01:12:36,370 --> 01:12:42,100
wa hii safu ya 3 integers kwamba nimepata zilizotengwa.

1164
01:12:42,100 --> 01:12:46,670
Hivyo sasa ninafanya nini, nyota pointer tu mabadiliko ya kipengele kwanza katika orodha.

1165
01:12:46,670 --> 01:12:49,140
Star pointer 1 pointi zaidi ya hapa.

1166
01:12:49,140 --> 01:12:53,140
Hivyo pointer ni zaidi ya hapa, pointer 1 ni zaidi ya hapa, pointer 2 ni zaidi ya hapa.

1167
01:12:53,140 --> 01:12:56,610
>> Hivyo kuongeza tu 1 ni kitu kimoja kama kusonga pamoja safu hii.

1168
01:12:56,610 --> 01:12:59,880
Tunachofanya ni kwamba, wakati sisi kufanya pointer 1 kupata anuani zaidi ya hapa,

1169
01:12:59,880 --> 01:13:04,180
na ili kupata thamani katika hapa, wewe kuweka nyota katika kutoka kujieleza nzima

1170
01:13:04,180 --> 01:13:05,990
kwa dereference yake.

1171
01:13:05,990 --> 01:13:09,940
Hivyo, katika kesi hii, mimi nina kuweka mahali kwanza katika safu hii kwa 1,

1172
01:13:09,940 --> 01:13:13,970
pili mahali kwa 2, na mahali ya tatu kwa 3.

1173
01:13:13,970 --> 01:13:18,180
Kisha nini mimi kufanya zaidi ya hapa ni mimi nina uchapishaji pointer yetu 1,

1174
01:13:18,180 --> 01:13:19,970
ambayo tu anitiaye 2.

1175
01:13:19,970 --> 01:13:23,650
Sasa mimi nina incrementing pointer, hivyo pointer sawa pointer 1,

1176
01:13:23,650 --> 01:13:26,780
ambayo moves ni mbele.

1177
01:13:26,780 --> 01:13:30,810
Na hivyo sasa kama mimi magazeti nje pointer 1, 1 pointer sasa ni 3,

1178
01:13:30,810 --> 01:13:33,990
ambayo katika kesi hii Prints nje 3.

1179
01:13:33,990 --> 01:13:36,560
Na ili kitu bure, pointer kwamba mimi kutoa

1180
01:13:36,560 --> 01:13:40,540
lazima akizungumzia katika mwanzo wa safu ambayo mimi got nyuma kutoka malloc.

1181
01:13:40,540 --> 01:13:43,430
Hivyo, katika kesi hii, kama ningekuwa kuwaita 3 haki hapa, hii bila kuwa na haki,

1182
01:13:43,430 --> 01:13:45,070
kwa sababu ni katikati ya safu.

1183
01:13:45,070 --> 01:13:48,820
Nina Ondoa kupata mahali awali

1184
01:13:48,820 --> 01:13:50,420
awali kwanza kabla doa naweza huru yake.

1185
01:13:56,300 --> 01:13:58,450
Kwa hiyo, hapa ni mfano kushiriki zaidi.

1186
01:13:58,450 --> 01:14:03,360
Katika kesi hii, sisi ni kugawa wahusika 7 katika safu tabia.

1187
01:14:03,360 --> 01:14:06,480
>> Na katika kesi hii ni nini sisi ni kufanya ni tuko looping juu ya 6 ya kwanza ya yao,

1188
01:14:06,480 --> 01:14:09,900
na sisi ni kuweka yao kwa Z.

1189
01:14:09,900 --> 01:14:13,350
Hivyo, kwa int i = 0, i> 6, i + +,

1190
01:14:13,350 --> 01:14:16,220
Hivyo, pointer + i tu kutupa, katika kesi hii,

1191
01:14:16,220 --> 01:14:20,860
pointer, pointer 1, 2 pointer, pointer 3, na kadhalika na kadhalika katika kitanzi.

1192
01:14:20,860 --> 01:14:24,040
Nini ni kwenda kufanya ni anapata kwamba anuani, dereferences ni kupata thamani,

1193
01:14:24,040 --> 01:14:27,440
na mabadiliko ambayo thamani kwa Z.

1194
01:14:27,440 --> 01:14:30,350
Kisha mwishoni kumbuka hii ni kamba, sawa?

1195
01:14:30,350 --> 01:14:33,560
Zote masharti kuwa na kumalizika na herufi null kuahirisha.

1196
01:14:33,560 --> 01:14:38,620
Hivyo, nini mimi kufanya ni katika pointer 6 mimi kuweka null Terminator tabia in

1197
01:14:38,620 --> 01:14:43,980
Na sasa nini mimi kimsingi kufanya zaidi ya hapa ni utekelezaji wa printf kwa kamba, sawa?

1198
01:14:43,980 --> 01:14:46,190
>> Hivyo, wakati gani printf sasa wakati ni kufikiwa mwisho ya kamba?

1199
01:14:46,190 --> 01:14:48,230
Wakati ni hits null kuahirisha tabia.

1200
01:14:48,230 --> 01:14:52,030
Hivyo, katika kesi hii, pointer yangu ya awali pointi ya mwanzo wa safu hii.

1201
01:14:52,030 --> 01:14:56,410
Mimi magazeti tabia ya kwanza nje. Mimi hoja yake juu ya moja.

1202
01:14:56,410 --> 01:14:58,420
Mimi magazeti kwamba tabia nje. Mimi hoja hiyo juu.

1203
01:14:58,420 --> 01:15:02,180
Na mimi kuendelea kufanya hili mpaka mimi kufikia mwisho.

1204
01:15:02,180 --> 01:15:07,750
Na sasa * mwisho pointer mapenzi dereference hii na kupata null kuahirisha tabia ya nyuma.

1205
01:15:07,750 --> 01:15:11,780
Na hivyo wakati wangu kitanzi anaendesha tu wakati thamani ambayo si null kuahirisha tabia.

1206
01:15:11,780 --> 01:15:13,770
Hivyo, sasa mimi exit nje ya kitanzi hii.

1207
01:15:18,780 --> 01:15:21,180
Na hivyo kama mimi Ondoa 6 kutoka pointer hii,

1208
01:15:21,180 --> 01:15:22,860
Mimi kurejea njia yote ya mwanzo.

1209
01:15:22,860 --> 01:15:27,880
Kumbuka, mimi nina kufanya hivi kwa sababu nina kwenda mwanzo ili kumwondolea yake.

1210
01:15:27,880 --> 01:15:30,270
>> Hivyo, najua kwamba ilikuwa mengi. Je, kuna maswali?

1211
01:15:30,270 --> 01:15:31,870
Tafadhali, ndiyo?

1212
01:15:31,870 --> 01:15:36,610
[Mwanafunzi swali unintelligible]

1213
01:15:36,610 --> 01:15:38,190
Je, unaweza kusema kwamba sauti? Sorry.

1214
01:15:38,190 --> 01:15:44,140
[Mwanafunzi] On slide mwisho kulia kabla ya waliokimbia pointer,

1215
01:15:44,140 --> 01:15:47,300
ambapo walikuwa wewe hasa kubadilisha thamani ya pointer?

1216
01:15:47,300 --> 01:15:50,370
[Joseph] Hivyo, haki hapa. >> [Mwanafunzi] Oh, okay.

1217
01:15:50,370 --> 01:15:51,890
[Joseph] Hivyo, nina pointer bala bala, haki,

1218
01:15:51,890 --> 01:15:54,140
ambayo moves jambo moja nyuma, na kisha mimi ni huru,

1219
01:15:54,140 --> 01:15:57,000
kwa sababu pointer hii ina kuelekezwa kwa mwanzo wa safu.

1220
01:15:57,000 --> 01:16:00,420
[Mwanafunzi] Lakini kwamba isingekuwa zinazohitajika alikuwa kusimamishwa baada ya mstari huo.

1221
01:16:00,420 --> 01:16:03,130
[Joseph] Hivyo, kama mimi alikuwa kusimamishwa baada ya hii, hii itakuwa kuchukuliwa leak kumbukumbu,

1222
01:16:03,130 --> 01:16:04,810
kwa sababu mimi si kukimbia bure.

1223
01:16:04,810 --> 01:16:11,290
[Mwanafunzi] Mimi [unintelligible] baada ya kwanza mistari mitatu ambapo alikuwa pointer 1 [unintelligible].

1224
01:16:11,290 --> 01:16:13,140
[Joseph] Uh-huh. Hivyo, nini ni swali huko?

1225
01:16:13,140 --> 01:16:14,780
Sorry. Hapana, hakuna. Nenda, kwenda, tafadhali.

1226
01:16:14,780 --> 01:16:16,870
[Mwanafunzi] Basi, wewe si kubadilisha thamani ya kuyatumia.

1227
01:16:16,870 --> 01:16:19,130
Wewe wasingalikuwa kufanya pointer bala bala.

1228
01:16:19,130 --> 01:16:19,730
[Joseph] Ndiyo, hasa.

1229
01:16:19,730 --> 01:16:21,890
Hivyo, wakati mimi kufanya pointer 1 na 2 pointer,

1230
01:16:21,890 --> 01:16:24,410
Mimi si kufanya pointer sawa pointer 1.

1231
01:16:24,410 --> 01:16:27,260
Hivyo, pointer tu anakaa akizungumzia katika mwanzo wa safu.

1232
01:16:27,260 --> 01:16:31,460
Ni wakati tu mimi kufanya plus plus kwamba unaweka thamani nyuma ndani pointer,

1233
01:16:31,460 --> 01:16:33,550
kwamba ni kweli hatua hii pamoja.

1234
01:16:36,860 --> 01:16:37,780
Wote haki.

1235
01:16:40,550 --> 01:16:42,030
Zaidi maswali?

1236
01:16:44,680 --> 01:16:47,790
>> Tena, kama hii ni aina ya balaa, hii itakuwa kufunikwa katika kikao.

1237
01:16:47,790 --> 01:16:50,710
Uliza mafundisho wenzako kuhusu hilo, na tunaweza kujibu maswali mwishoni.

1238
01:16:53,510 --> 01:16:56,600
Na kwa kawaida sisi si kama jambo hili bala.

1239
01:16:56,600 --> 01:16:59,760
Hii ina kuhitaji me kuweka wimbo wa kiasi gani nimepata kukabiliana katika safu.

1240
01:16:59,760 --> 01:17:04,520
Hivyo, kwa ujumla, hii ni kueleza jinsi matendo arithmetic pointer.

1241
01:17:04,520 --> 01:17:07,970
Lakini nini sisi kwa kawaida kama kwa kufanya ni sisi kama kujenga nakala ya pointer,

1242
01:17:07,970 --> 01:17:11,640
na kisha tutaweza kutumia nakala wakati sisi ni kuhamia karibu katika kamba.

1243
01:17:11,640 --> 01:17:14,660
Hivyo, katika kesi hizi unaweza kutumia nakala ya magazeti ya string nzima,

1244
01:17:14,660 --> 01:17:19,040
lakini hatuna la kufanya kama pointer minus 6 au kuweka wimbo wa kiasi gani sisi wakiongozwa katika hili,

1245
01:17:19,040 --> 01:17:22,700
tu kwa sababu tunajua kwamba hatua yetu ya awali bado alisema kwa mwanzo wa orodha

1246
01:17:22,700 --> 01:17:25,340
na wote kwamba sisi ilibadilika ilikuwa hii nakala.

1247
01:17:25,340 --> 01:17:28,250
Hivyo, kwa ujumla, kubadilisha nakala za pointer yako ya awali.

1248
01:17:28,250 --> 01:17:32,350
Je, si kujaribu kutatua ya kama - don't kubadilisha nakala ya awali.

1249
01:17:32,350 --> 01:17:35,290
Kujaribu kubadilisha nakala tu ya awali yako.

1250
01:17:41,540 --> 01:17:44,870
Hivyo, taarifa wakati sisi kupitisha kamba ndani ya printf

1251
01:17:44,870 --> 01:17:48,990
huna kuweka nyota mbele yake kama tulivyofanya kwa dereferences mengine yote, sawa?

1252
01:17:48,990 --> 01:17:54,180
Hivyo, kama wewe magazeti nje mzima string% s anatarajia ni anwani,

1253
01:17:54,180 --> 01:17:57,610
na katika kesi hii pointer au katika kesi hii kama safu ya wahusika.

1254
01:17:57,610 --> 01:18:00,330
>> Nyingine, char * s, na arrays ni kitu kimoja.

1255
01:18:00,330 --> 01:18:03,690
Pointer ni kwa wahusika, na tabia arrays ni kitu kimoja.

1256
01:18:03,690 --> 01:18:05,720
Na hivyo, wote sisi kufanya ni kupita katika pointer.

1257
01:18:05,720 --> 01:18:08,150
Hatuna kupita katika kama * pointer au kitu kama hicho.

1258
01:18:13,110 --> 01:18:14,930
Hivyo, arrays na kuyatumia ni kitu kimoja.

1259
01:18:14,930 --> 01:18:19,160
Wakati wewe kufanya kitu kama x [y] zaidi ya hapa kwa safu,

1260
01:18:19,160 --> 01:18:21,960
kile ni kufanya chini ya Hood ni ni kusema, sawa, ni safu ya tabia,

1261
01:18:21,960 --> 01:18:23,690
hivyo ni pointer.

1262
01:18:23,690 --> 01:18:26,510
Na hivyo x ni kitu kimoja,

1263
01:18:26,510 --> 01:18:28,650
na hivyo kile yake ni inaongeza y x,

1264
01:18:28,650 --> 01:18:31,820
ambayo ni kitu kimoja kama kusonga mbele katika kumbukumbu kwamba mengi.

1265
01:18:31,820 --> 01:18:34,930
Na sasa x + y inatupa baadhi ya aina ya anwani,

1266
01:18:34,930 --> 01:18:37,570
na sisi dereference anuani au kufuata mshale

1267
01:18:37,570 --> 01:18:41,640
kwa kuwa mahali ambapo katika kumbukumbu ni sisi na kupata thamani nje ya kwamba mahali katika kumbukumbu.

1268
01:18:41,640 --> 01:18:43,720
Hivyo, hivyo hizi mbili ni hasa kitu kimoja.

1269
01:18:43,720 --> 01:18:45,840
Ni tu sukari kisintaksia.

1270
01:18:45,840 --> 01:18:48,090
Wao kufanya kitu kimoja. Wao ni tu syntactics tofauti kwa kila mmoja.

1271
01:18:51,500 --> 01:18:57,590
>> Hivyo, nini unaweza kwenda vibaya na kuyatumia? Kama, mengi. Sawa. Hivyo, mambo mabaya.

1272
01:18:57,590 --> 01:19:02,410
Baadhi ya mambo mabaya unaweza kufanya ni kuangalia kama si malloc wako wa simu ya anarudi null, haki?

1273
01:19:02,410 --> 01:19:06,560
Katika kesi hiyo, mimi nina kuuliza mfumo kunipa - kile ni kwamba idadi hiyo?

1274
01:19:06,560 --> 01:19:11,200
Bilioni 2 kama mara 4, kwa sababu ya ukubwa wa integer ni 4 ka.

1275
01:19:11,200 --> 01:19:13,810
Mimi nauliza hivyo kwa ajili kama ka bilioni 8.

1276
01:19:13,810 --> 01:19:17,270
Bila shaka kompyuta yangu si kwenda kuwa na uwezo wa nipe kumbukumbu kubwa zaidi nyuma.

1277
01:19:17,270 --> 01:19:20,960
Na sisi hawakuwa kuangalia kama hii ni null, hivyo wakati sisi kujaribu dereference ni zaidi ya hapo -

1278
01:19:20,960 --> 01:19:24,270
kufuata mshale ambapo itakavyo - hatuna kwamba kumbukumbu.

1279
01:19:24,270 --> 01:19:27,150
Hii ni nini tunaita dereferencing pointer null.

1280
01:19:27,150 --> 01:19:29,710
Na hii kimsingi sababu wewe segfault.

1281
01:19:29,710 --> 01:19:31,790
Hii ni moja ya njia unaweza segfault.

1282
01:19:34,090 --> 01:19:38,090
Nyingine mbaya ya mambo unaweza kufanya - oh vizuri.

1283
01:19:38,090 --> 01:19:40,650
Hiyo ilikuwa dereferencing pointer null. Sawa.

1284
01:19:40,650 --> 01:19:45,160
Mambo mengine mabaya - vizuri, kurekebisha kwamba wewe tu kuweka hundi katika huko

1285
01:19:45,160 --> 01:19:46,980
kwamba hundi kama pointer ni null

1286
01:19:46,980 --> 01:19:51,000
na exit nje ya mpango kama ni hutokea malloc kwamba anarudi pointer null.

1287
01:19:55,110 --> 01:19:59,850
Hiyo Comic XKCD. Watu kuelewa sasa. Aina ya.

1288
01:20:06,120 --> 01:20:09,350
>> Hivyo, kumbukumbu. Nikatoka juu ya hili.

1289
01:20:09,350 --> 01:20:12,000
Sisi ni wito malloc katika kitanzi, lakini kila wakati sisi kuwaita malloc

1290
01:20:12,000 --> 01:20:14,370
sisi ni kupoteza track ya pointer ambapo hii ni akizungumzia,

1291
01:20:14,370 --> 01:20:15,750
kwa sababu sisi ni clobbering yake.

1292
01:20:15,750 --> 01:20:18,410
Hivyo, wito wa awali kwa malloc anitiaye kumbukumbu zaidi ya hapa.

1293
01:20:18,410 --> 01:20:19,990
Pointer yangu kuyatumia na hii.

1294
01:20:19,990 --> 01:20:23,020
Sasa, sijui huru, hivyo sasa mimi wito malloc tena.

1295
01:20:23,020 --> 01:20:26,070
Sasa pointi zaidi ya hapa. Sasa kumbukumbu yangu ni kuonyesha zaidi ya hapa.

1296
01:20:26,070 --> 01:20:27,640
Akizungumzia zaidi ya hapa. Akizungumzia zaidi ya hapa.

1297
01:20:27,640 --> 01:20:31,820
Lakini nimekuwa waliopotea track ya anwani ya kumbukumbu ya juu hapa kwamba mimi zilizotengwa wote.

1298
01:20:31,820 --> 01:20:35,100
Na hivyo sasa sina ushahidi wowote nao tena.

1299
01:20:35,100 --> 01:20:37,230
Hivyo, naweza kuwa huru na wao nje ya kitanzi hii.

1300
01:20:37,230 --> 01:20:39,390
Na hivyo ili kurekebisha kitu kama hii,

1301
01:20:39,390 --> 01:20:42,250
kama wewe kusahau kumbukumbu bure na wewe kupata hii leak kumbukumbu,

1302
01:20:42,250 --> 01:20:45,810
Una huru kumbukumbu ndani ya kitanzi hii mara moja wewe ni kosa kwa hayo.

1303
01:20:45,810 --> 01:20:51,400
Naam, hii ni nini kinatokea. Najua kura ya chuki hii.

1304
01:20:51,400 --> 01:20:55,270
Lakini sasa - Yay! Unaweza kupata kama kilobytes 44,000.

1305
01:20:55,270 --> 01:20:57,110
Hivyo, wewe ni huru mwishoni mwa kitanzi,

1306
01:20:57,110 --> 01:20:59,770
na kwamba itakuja tu huru kumbukumbu kila wakati.

1307
01:20:59,770 --> 01:21:03,620
Kimsingi, programu yako haina leak kumbukumbu tena.

1308
01:21:03,620 --> 01:21:08,150
>> Na sasa kitu kingine unaweza kufanya ni huru baadhi ya kumbukumbu kwamba ve aliuliza kwa mara mbili.

1309
01:21:08,150 --> 01:21:11,060
Katika kesi hiyo, wewe malloc kitu, wewe kubadilisha thamani yake.

1310
01:21:11,060 --> 01:21:13,140
Wewe ni huru mara moja kutokana na wewe alisema yalifanyika kwa hayo.

1311
01:21:13,140 --> 01:21:14,940
Lakini basi sisi huru tena.

1312
01:21:14,940 --> 01:21:16,730
Hii ni kitu ambacho ni pretty mbaya.

1313
01:21:16,730 --> 01:21:18,820
Ni si kwenda awali segfault,

1314
01:21:18,820 --> 01:21:23,350
lakini baada ya muda gani hii haina ni mara mbili ya kumkomboa hii huharibu lundo yako muundo,

1315
01:21:23,350 --> 01:21:27,200
na wewe utakuwa kujifunza kidogo zaidi kuhusu hili kama wewe kuchagua kuchukua darasa kama CS61.

1316
01:21:27,200 --> 01:21:30,000
Lakini kimsingi baada ya wakati kompyuta yako ni kwenda kupata kuchanganyikiwa

1317
01:21:30,000 --> 01:21:33,010
kuhusu nini kumbukumbu maeneo ni wapi na ambapo ni kuhifadhiwa -

1318
01:21:33,010 --> 01:21:34,800
ambapo data ni kuhifadhiwa katika kumbukumbu.

1319
01:21:34,800 --> 01:21:38,080
Na hivyo kumkomboa pointer mara mbili ni jambo mbaya kwamba hutaki kufanya.

1320
01:21:38,080 --> 01:21:41,600
>> Mambo mengine ambayo yanaweza kwenda vibaya si kutumia sizeof.

1321
01:21:41,600 --> 01:21:44,460
Hivyo, katika kesi hii wewe malloc ka 8,

1322
01:21:44,460 --> 01:21:46,700
na kwamba ni kitu kimoja kama integers mbili, sawa?

1323
01:21:46,700 --> 01:21:49,580
Hivyo, hiyo ni kikamilifu salama, lakini ni nini?

1324
01:21:49,580 --> 01:21:52,160
Naam, kama Lucas walizungumzia juu ya usanifu tofauti,

1325
01:21:52,160 --> 01:21:54,220
integers ni ya urefu tofauti.

1326
01:21:54,220 --> 01:21:57,970
Hivyo, juu ya appliance kwamba wewe ni kutumia, integers ni kuhusu 4 ka,

1327
01:21:57,970 --> 01:22:02,370
lakini juu ya mfumo wa baadhi ya wengine wapate kuwa 8 ka au wanaweza kuwa 16 bytes.

1328
01:22:02,370 --> 01:22:05,680
Hivyo, kama mimi tu kutumia namba hii zaidi ya hapa,

1329
01:22:05,680 --> 01:22:07,310
mpango huu ili kazi juu ya appliance,

1330
01:22:07,310 --> 01:22:10,360
lakini si kwenda kutenga kumbukumbu ya kutosha juu ya mfumo wa baadhi nyingine.

1331
01:22:10,360 --> 01:22:14,020
Katika kesi hiyo, hii ni nini operator sizeof ni kutumika kwa.

1332
01:22:14,020 --> 01:22:16,880
Wakati sisi kuwaita sizeof (int), nini hii haina ni

1333
01:22:16,880 --> 01:22:21,910
 ni inatupa ukubwa wa integer juu ya mfumo wa kwamba mpango ni mbio.

1334
01:22:21,910 --> 01:22:25,490
Hivyo, katika kesi hii, sizeof (int) atarudi 4 juu ya kitu kama appliance,

1335
01:22:25,490 --> 01:22:29,980
na sasa hii mapenzi 4 * 2, ambayo ni 8,

1336
01:22:29,980 --> 01:22:32,330
ambayo ni ya haki kiasi cha nafasi muhimu kwa integers mbili.

1337
01:22:32,330 --> 01:22:36,710
Juu ya mfumo tofauti, ikiwa ni int kama ka 16 au ka 8,

1338
01:22:36,710 --> 01:22:39,380
ni tu kwenda na kurudi ka kutosha kuhifadhi kwamba kiasi.

1339
01:22:41,830 --> 01:22:45,310
>> Na hatimaye, structs.

1340
01:22:45,310 --> 01:22:48,340
Hivyo, kama alitaka kuhifadhi bodi Sudoku katika kumbukumbu, jinsi tunavyoweza kufanya hili?

1341
01:22:48,340 --> 01:22:51,570
Unaweza kufikiri ya kama variable kwa jambo la kwanza,

1342
01:22:51,570 --> 01:22:53,820
kutofautiana kwa Jambo la pili, kutofautiana kwa jambo la tatu,

1343
01:22:53,820 --> 01:22:56,420
kutofautiana kwa jambo la nne - mbaya, haki?

1344
01:22:56,420 --> 01:23:00,750
Hivyo, moja uboreshaji unaweza kufanya juu ya hii ni kufanya 9 x 9 safu.

1345
01:23:00,750 --> 01:23:04,480
Hiyo ni sawa, lakini kile kama alitaka kujiunga na mambo mengine na bodi Sudoku

1346
01:23:04,480 --> 01:23:06,490
kama nini ugumu wa bodi ni,

1347
01:23:06,490 --> 01:23:11,740
au, kwa mfano, kile alama yako ni, au jinsi gani wakati ni kuchukuliwa wewe kutatua hii bodi?

1348
01:23:11,740 --> 01:23:14,970
Naam, nini unaweza kufanya ni unaweza kuunda struct.

1349
01:23:14,970 --> 01:23:18,910
Nini mimi kimsingi akisema ni mimi nina kufafanua muundo huu zaidi ya hapa,

1350
01:23:18,910 --> 01:23:23,230
na mimi nina kufafanua bodi Sudoku ambalo lina bodi kwamba ni 9 x 9.

1351
01:23:23,230 --> 01:23:26,650
>> Na nini ina ina kuyatumia kwa jina la ngazi.

1352
01:23:26,650 --> 01:23:30,730
Pia ina x na y, ambayo ni kuratibu ya ambapo mimi hivi sasa.

1353
01:23:30,730 --> 01:23:35,980
Pia ina wakati alitumia [unintelligible], na ina jumla ya idadi ya hatua nimekuwa inputted hivyo mbali.

1354
01:23:35,980 --> 01:23:40,010
Na hivyo katika kesi hii, naweza kikundi rundo zima la data katika muundo moja tu

1355
01:23:40,010 --> 01:23:42,790
badala ya kuwa ni kama kuruka karibu katika kama vigezo mbalimbali

1356
01:23:42,790 --> 01:23:44,540
kwamba siwezi kuweka wimbo wa.

1357
01:23:44,540 --> 01:23:49,720
Na hii inatusaidia kuwa nzuri tu syntax kwa aina ya referencing mambo mbalimbali ndani ya struct hii.

1358
01:23:49,720 --> 01:23:53,430
Naweza tu kufanya board.board, na mimi kupata bodi Sudoku nyuma.

1359
01:23:53,430 --> 01:23:56,320
Board.level, mimi kupata jinsi ngumu ni.

1360
01:23:56,320 --> 01:24:00,540
Board.x na board.y nipe viwianishi vya ambapo nipate kuwa katika bodi.

1361
01:24:00,540 --> 01:24:04,730
Na hivyo mimi nina kupata kile tunachokiita mashamba katika struct.

1362
01:24:04,730 --> 01:24:08,840
Hii amefafanua sudokuBoard, ambayo ni aina ya kwamba nina.

1363
01:24:08,840 --> 01:24:14,800
Na sasa tuko hapa. Nina variable inayoitwa "bodi" ya sudokuBoard aina.

1364
01:24:14,800 --> 01:24:18,820
Na hivyo mimi sasa wanaweza kupata mashamba yote ambayo yanafanya muundo huu zaidi ya hapa.

1365
01:24:20,830 --> 01:24:22,450
>> Maswali yoyote kuhusu structs? Ndiyo?

1366
01:24:22,450 --> 01:24:25,890
[Mwanafunzi] Kwa int x, y, wewe alitangaza wote kwenye mstari mmoja? >> [Joseph] Uh-huh.

1367
01:24:25,890 --> 01:24:27,400
[Mwanafunzi] Hivyo, unaweza tu kufanya hivyo kwa wote?

1368
01:24:27,400 --> 01:24:31,200
Kama ilivyo katika x, y comma mara kwamba jumla?

1369
01:24:31,200 --> 01:24:34,460
[Joseph] Ndiyo, unaweza dhahiri kufanya hivyo, lakini sababu mimi kuweka x na y juu ya mstari huo -

1370
01:24:34,460 --> 01:24:36,330
na swali ni kwa nini tunaweza tu kufanya hivyo kwenye mstari huo?

1371
01:24:36,330 --> 01:24:38,600
Mbona sisi tu ya kuweka yote haya juu ya mstari huo ni

1372
01:24:38,600 --> 01:24:42,090
x na y ni kuhusiana na kila mmoja,

1373
01:24:42,090 --> 01:24:44,780
na hii ni stylistically sahihi zaidi, katika hisia,

1374
01:24:44,780 --> 01:24:46,600
kwa sababu ni kuweka viumbe mbili juu ya mstari huo

1375
01:24:46,600 --> 01:24:49,340
kwamba aina kama ya yanahusiana na kitu kimoja.

1376
01:24:49,340 --> 01:24:51,440
Na mimi tu pasua hizi mbali. Ni tu kitu style.

1377
01:24:51,440 --> 01:24:53,720
Ni functionally hufanya hakuna tofauti yo yote.

1378
01:24:58,150 --> 01:24:59,270
Maswali yoyote juu ya nyingine structs?

1379
01:25:03,030 --> 01:25:06,620
Unaweza kufafanua Pokédex na struct.

1380
01:25:06,620 --> 01:25:11,720
Pokemon ina idadi na ina barua, mmiliki, aina.

1381
01:25:11,720 --> 01:25:16,990
Na kisha kama una safu ya pokemon, unaweza kufanya juu Pokédex, haki?

1382
01:25:16,990 --> 01:25:20,810
Okay, cool. Hivyo, maswali juu ya structs. Wale ni kuhusiana na structs.

1383
01:25:20,810 --> 01:25:25,270
>> Hatimaye, GDB. Je GDB basi wewe kufanya? Ni inakuwezesha Debug programu yako.

1384
01:25:25,270 --> 01:25:27,650
Na kama hujatumia GDB, napenda ilipendekeza kuangalia mfupi

1385
01:25:27,650 --> 01:25:31,250
na kwenda tu juu ya kile GDB ni, jinsi kazi pamoja na hayo, jinsi unavyoweza kutumia hiyo,

1386
01:25:31,250 --> 01:25:32,900
na mtihani juu ya mpango.

1387
01:25:32,900 --> 01:25:37,400
Na hivyo kile GDB inakuwezesha kufanya ni inakuwezesha pause [unintelligible] juu ya mpango wako

1388
01:25:37,400 --> 01:25:38,920
na mstari wa vitendo.

1389
01:25:38,920 --> 01:25:42,600
Kwa mfano, nataka utekelezaji pause katika mstari kama 3 ya mpango wangu,

1390
01:25:42,600 --> 01:25:46,010
na wakati mimi nina katika mstari wa 3 Naweza magazeti nje maadili yote yaliyoko.

1391
01:25:46,010 --> 01:25:49,710
Na hivyo kile tunachokiita kama pausing katika mstari

1392
01:25:49,710 --> 01:25:52,350
ni sisi wito kuweka breakpoint katika mstari kwamba

1393
01:25:52,350 --> 01:25:55,920
na kisha tunaweza magazeti nje vigezo katika hali ya programu wakati huo.

1394
01:25:55,920 --> 01:25:58,990
>> Tunaweza halafu kutoka hapo hatua kupitia mpango line-na-line.

1395
01:25:58,990 --> 01:26:03,200
Na kisha tunaweza kuangalia hali ya stack kwa wakati.

1396
01:26:03,200 --> 01:26:08,600
Na hivyo ili kutumia GDB, nini cha kufanya ni sisi wito Clang kwenye faili C,

1397
01:26:08,600 --> 01:26:11,290
lakini tuna kupita ggdb-bendera.

1398
01:26:11,290 --> 01:26:15,850
Na mara moja sisi ni kosa na kwamba sisi kukimbia tu gdb kwenye faili kusababisha pato.

1399
01:26:15,850 --> 01:26:18,810
Na ili kupata baadhi ya molekuli kama ya maandishi kama hii,

1400
01:26:18,810 --> 01:26:21,990
lakini kwa kweli yote wewe kufanya ni aina katika amri mwanzoni.

1401
01:26:21,990 --> 01:26:24,250
Kuvunja kuu unaweka breakpoint katika kuu.

1402
01:26:24,250 --> 01:26:28,470
Orodha ya 400 unaorodhesha mstari wa kanuni kuzunguka mstari 400.

1403
01:26:28,470 --> 01:26:31,410
Na hivyo katika kesi hii unaweza kuangalia tu karibu na kusema, oh,

1404
01:26:31,410 --> 01:26:34,360
Nataka kuweka breakpoint katika mstari wa 397, ambayo ni mstari huu,

1405
01:26:34,360 --> 01:26:37,170
na kisha programu yako anaendesha katika hatua hiyo na ni kwenda kuvunja.

1406
01:26:37,170 --> 01:26:41,120
Ni kwenda pause huko, na unaweza magazeti nje, kwa mfano, thamani ya chini au ya juu.

1407
01:26:41,120 --> 01:26:46,410
Na hivyo kuna rundo la amri unahitaji kujua,

1408
01:26:46,410 --> 01:26:48,660
na slideshow hii kwenda juu kwenye tovuti,

1409
01:26:48,660 --> 01:26:54,000
hivyo kama unataka tu kwa rejea hizi au kama kuweka yao kwenye karatasi yako ya kudanganya, jisikie huru.

1410
01:26:54,000 --> 01:27:00,650
>> Cool. Hiyo ilikuwa Quiz Review 0, na tutaweza fimbo karibu kama una maswali yoyote.

1411
01:27:00,650 --> 01:27:03,850
Wote haki.

1412
01:27:03,850 --> 01:27:09,030
>>  [Applause]

1413
01:27:09,030 --> 01:27:13,000
>> [CS50.TV]