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[Powered by Google Translate] [Sehemu ya 4] [Less Starehe]

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[Nate Hardison] [Chuo Kikuu cha Harvard]

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[Hii ni CS50.] [CS50.TV]

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>> Haki zote, kuwakaribisha nyuma kwa sehemu.

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Katika sehemu ya wiki hii sisi ni kwenda kufanya mambo kadhaa.

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Sisi ni kwenda kwanza Set recap Tatizo 2,

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ambayo ni tatizo Kaisari na Vigenère kuweka.

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Na kisha sisi ni kwenda kupiga mbizi katika Quiz mapitio 0

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na kutumia muda kidogo recapping kile ambacho tumekuwa aliyesema kuhusu

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katika kila moja ya mihadhara hivyo mbali, na pia tutaweza kufanya matatizo machache

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kutoka Quizzes wa mwaka uliopita.

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Kwa njia hiyo guys kuwa njia nzuri ya kujiandaa kwa ajili hiyo.

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>> Kuanza, nimekuwa booted juu ya wanandoa wa ufumbuzi mzuri

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kwa ajili ya kuweka uliopita tatizo, Tatizo Kuweka 2, katika nafasi hii.

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Kama wewe guys wote hit link hii,

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na kama wewe bonyeza jina langu na bonyeza marekebisho yangu ya kwanza

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utaona caesar.c, ambayo ni hasa kile Mimi nina kuangalia.

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Hebu majadiliano kuhusu kweli hii haraka.

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Hii ni ufumbuzi sampuli.

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Hii ni lazima si suluhisho kamili.

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Kuna njia nyingi tofauti ya kuandika hii,

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lakini kuna mambo machache ambayo mimi alitaka kuonyesha

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kwamba nikaona kama nilikuwa grading, kawaida makosa ambayo nadhani

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ufumbuzi hii haina kazi nzuri sana ya kuchukua.

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>> kwanza ni kuwa na aina fulani ya maoni header kwa juu.

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Juu ya mistari 1 hadi 7, unaweza kuona maelezo,

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nini hasa mpango huu ni kufanya.

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nzuri kiwango mazoezi wakati wewe kuandika code C

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bila kujali kama mpango wako ni zilizomo ndani ya faili moja au

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kama ni mgawanyiko juu ya files nyingi ni kuwa na aina fulani ya

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orienting maoni kwa juu.

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Hii pia ni kwa ajili ya watu kwenda nje na kuandika code katika ulimwengu wa kweli.

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Hii ni pale ambapo itabidi kuweka hati miliki ya habari.

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Chini ni pamoja na #.

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On line 16 kuna hii # define, ambayo tutaweza kurudi katika kidogo tu.

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Na kisha mara moja kazi kuanza, kuanza mara moja kuu,

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kwa sababu mpango huu imekuwa zote zilizomo katika kazi moja

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kitu ya kwanza kabisa kwamba kinachotokea-na hii ni nahau au msemo wenye sana na mfano wa mpango C

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kwamba inachukua katika mstari amri hoja-ni kwamba mara hundi

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>> kwa kuhesabu hoja, argc.

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Haki hapa tunaona kwamba mpango huu ni kutarajia hoja 2 hasa.

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Kumbuka kwamba kuna hoja ya kwanza kwamba moja maalum

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kwamba daima jina la mpango hiyo kuwa kukimbia,

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jina la faili la kutekelezwa.

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Na hivyo kile hii haina ni linazuia mtumiaji kutoka mbio mpango

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kwa hoja zaidi au wachache.

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sababu tunataka kuangalia kwa haki hii kwa sababu ni mbali

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hatuwezi kupata hii safu argv haki hapa reliably

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mpaka tumekuwa checked kuona jinsi kubwa ni.

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>> Moja ya makosa ya kawaida niliyemwona alikuwa watu itakuwa mara kwenda katika

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na kunyakua argv [1].

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Wao d kunyakua hoja muhimu nje ya safu na kufanya kwa i kuangalia juu yake,

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na kisha wao d kufanya mtihani kwa argc kama vile mtihani ujao,

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kama au hoja ya kwanza ilikuwa kweli integer wakati huo huo,

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na kwamba haifanyi kazi kwa sababu katika kesi kwamba hakuna hoja zinazotolewa

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wewe utakuwa grabbing hoja kuwa si huko au kujaribu kunyakua moja kwamba si huko.

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>> nyingine jambo kubwa kwamba wewe lazima taarifa ni kwamba

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wewe siku zote wanataka magazeti nje baadhi ya aina ya ujumbe kusaidia kosa

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kwa mtumiaji kuelekeza yao.

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Mimi nina uhakika wameweza mipango yote ya kukimbia ambapo ghafla ni shambulio,

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na wewe kupata hii ridiculous kidogo dialog kwamba pops up na anasema

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kitu horribly cryptic na labda inakupa code kosa au kitu kama hicho

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kwamba haina mantiki.

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Hii ni pale ambapo kweli unataka kutoa kitu manufaa

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na walengwa kwa mtumiaji ili wakati wao kukimbia wao kwenda "Oh," uso mitende.

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"Mimi kujua hasa nini cha kufanya mimi. Kujua jinsi ya kurekebisha hii."

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>> Kama huna magazeti ujumbe, kisha kuishia kweli

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kuondoka mtumiaji kwenda kuchunguza chanzo yako code

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kufikiri nini potoka.

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Pia kuna baadhi ya nyakati utakayoitumia codes makosa mbalimbali.

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Hapa sisi tu kutumika moja kwa kusema kulikuwa na kosa,

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kulikuwa na hitilafu, kulikuwa na hitilafu.

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Bigger mipango, mara nyingi mipango ambayo huitwa na programu nyingine,

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atarudi na aina fulani ya namba maalum makosa katika matukio tofauti

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kwa programmatically kuwasiliana nini vinginevyo

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tu kutumia nzuri Kiingereza ujumbe kwa.

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Cool.

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Kama sisi kazi chini, unaweza kuona sisi kujiondoa muhimu.

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Sisi mtihani kuona kama ufunguo inafaa.

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Sisi kupata ujumbe kutoka kwa mtumiaji.

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sababu kufanya hivyo katika hii kufanya wakati kitanzi-na hili ni jambo ambalo sisi itafikia

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katika kidogo kidogo-lakini zinageuka kuwa kama aina kudhibiti D

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wakati kupata GetString kwamba haraka juu ya terminal

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kile kwamba kweli hana ni inapeleka tabia maalum

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kwa mpango.

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Ni wito ELF au mwisho wa tabia ya faili.

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Na katika kesi hiyo, ujumbe wetu string itakuwa null,

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hivyo hii ilikuwa si kitu sisi checked kwa tatizo katika kuweka yenyewe.

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>> Lakini kama sisi kwenda juu, sasa kwamba tumekuwa walianza kuzungumzia kuyatumia

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na nguvu juu ya kumbukumbu mgao wa chungu,

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kuangalia kwa null wakati wowote una kazi ambayo inaweza

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kurudi null kama thamani ni kitu ambacho utasikia wanataka kupata katika tabia ya kufanya.

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Hii ni hapa hasa kwa ajili ya vielelezo.

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Lakini wakati wa kufanya kuona GetString katika siku zijazo,

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hivyo kutokana na tatizo Set 4 juu, utasikia wanataka kuweka hii katika akili.

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Tena, hii si suala kwa Matatizo Kuweka 3 aidha tangu tulikuwa na si mifuniko ni bado.

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Hatimaye, sisi kupata sehemu hii ambapo sisi kupata kitanzi kuu fiche,

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na kuna michache ya mambo kinachoendelea hapa.

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Kwanza, sisi iterate zaidi string nzima ujumbe yenyewe.

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Hapa tumekuwa naendelea wito strlen katika hali,

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ambapo idadi ya wewe alisema si njia kuu ya kwenda.

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Ni zinageuka katika kesi hii ni pia si kubwa,

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sehemu kwa sababu sisi ni kubadilisha yaliyomo ya ujumbe yenyewe

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ndani kwa kitanzi, hivyo kama tuna ujumbe kwamba 10 wahusika muda mrefu,

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mara ya kwanza sisi kuanza kwamba kwa kitanzi strlen atarudi nini?

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10.

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>> Lakini kama sisi kisha kurekebisha ujumbe, kusema sisi kurekebisha tabia yake ya 5,

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na sisi kutupa katika tabia \ 0 katika nafasi 5,

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juu ya iteration baadae strlen (ujumbe) hatarejea zifanya

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mara ya kwanza sisi iterated,

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lakini itakuwa badala kurudi 5 kwa sababu sisi akatupa katika kwamba Terminator null,

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na urefu wa kamba ya hufafanuliwa

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na nafasi ya kuwa \ 0.

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Katika kesi hiyo, hii ni njia kuu ya kwenda kwa sababu sisi ni kubadilisha katika mahali.

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Lakini utaona kwamba hii ni kweli kushangaza rahisi encrypt

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kama unaweza kupata math sahihi.

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Vitu tu vinavyohitajika ni kuangalia kama au barua kwamba wewe kuangalia

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ni uppercase au lowercase.

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>> sababu sisi tu na kuangalia kwa kuwa na hatuna kuangalia kwa

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ni alpha kesi ni kwa sababu

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kama tabia ni uppercase au kama ni lowercase

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basi ni dhahiri tabia za kialfabeti,

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kwa sababu hatuna tarakimu kubwa na ndogo.

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Kitu nyingine sisi kufanya-na hii ni gumu kidogo-

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ni tumekuwa iliyopita kiwango Kaisari cipher formula

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kwamba sisi alitoa katika vipimo kuweka tatizo.

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Nini tofauti hapa ni kwamba sisi subtracted

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katika mji mkuu uppercase kesi, na kisha sisi aliongeza mtaji

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nyuma katika mwishoni.

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>> Mimi najua wachache una hii kufanyika katika code yako.

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Je yoyote ya kufanya hivyo katika maoni yako?

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Ulifanya hii. Je, unaweza kueleza nini hii haina, Sahb?

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Kwa kutoa nje, kwa sababu wewe ulifanya Mod haki baada ya hayo,

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una kuchukua nje, na hivyo njia ya kupata [kukohoa] msimamo.

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Na kisha kwa kuongeza kuwa nyuma baadaye kubadilishwa zaidi ya moja kwamba alitaka.

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Yeah, kwa uhakika.

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Nini Sahb alisema ilikuwa kwamba wakati tunataka kuongeza

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ujumbe wetu na ufunguo wetu pamoja

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na kisha Mod kwamba, Mod kwamba kwa NUM_LETTERS,

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kama hatuwezi kuongeza ujumbe wetu katika mbalimbali sahihi 0-25 kwanza,

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basi tunaweza kuishia kupata idadi kweli weird

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kwa sababu maadili ya kwamba sisi ni kuangalia wakati sisi kuangalia ujumbe [i],

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wakati sisi kuangalia tabia idh ya ujumbe wetu wazi-maandishi,

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ni thamani mahali fulani katika hii mbalimbali 65-122

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msingi maadili ASCII kwa uppercase kupitia z lowercase.

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Na hivyo wakati sisi Mod hivyo kwa 26 au kwa NUM_LETTERS,

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tangu kwamba alikuwa yetu # define juu kulia hapa juu,

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ambayo inaenda kutupa thamani hiyo ni katika mbalimbali 0-25,

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na tunahitaji njia kisha kuongeza kuwa nyuma hadi

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na kupata katika mbalimbali sahihi ASCII.

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Njia rahisi ya kufanya hivyo ni kuongeza tu kila kitu chini

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katika mbalimbali 0-25 kwa kuanzia,

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na kisha kuhama kila kitu nyuma hadi mwishoni.

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>> Kosa lingine la kawaida kwamba nikaona watu kukimbia katika ni kwamba

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kama wewe si kweli kufanya hivyo kuongeza haki mbali

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na wewe kuongeza ujumbe muhimu na pamoja na wewe kuongeza yao, kusema,

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ndani ya variable Char, tatizo na kwamba

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ni tangu ujumbe [i] ni idadi kubwa kiasi ya kuanza kwa-

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kumbuka ni angalau 65 ikiwa ni uppercase tabia-

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kama una ufunguo kubwa, wanasema, kitu kama 100,

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na kuongeza wale 2 pamoja katika Char saini utaenda kupata kufurika.

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Wewe ni kwenda kupata thamani hiyo ni kubwa kuliko 127,

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ambayo ni ya thamani kubwa kwamba variable Char wanaweza kushikilia.

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Tena, kwamba ni kwa nini wewe d wanataka kufanya aina ya kitu kwa kuanzia.

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Baadhi ya watu got karibu kesi kwamba kwa kufanya kama mwingine na kupima

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kuona kama ingekuwa kufurika kabla ya kufanya hivyo,

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lakini njia hii anapata karibu kwamba.

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Na kisha katika ufumbuzi hii sisi kuchapishwa string nzima mwishoni sana.

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Watu wengine kuchapishwa tabia kwa wakati. Wote ni kutisha.

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Katika hatua hii, je, wewe guys una maswali yoyote, maoni yoyote kuhusu hili?

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Mambo kama, mambo si kama?

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>> Mimi nilikuwa na swali.

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Labda mimi missed hiyo wakati maelezo yako, lakini jinsi gani mpango huu

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ruka nafasi kwa ajili ya kuunganisha muhimu kwa urefu wa maandishi?

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Hii ni Kaisari cipher. >> Oh, sorry, yeah.

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Yeah, tutaweza kuona kwamba.

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Katika cipher Kaisari tulipata kuzunguka kwamba kwa sababu

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sisi tu flipped wahusika.

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Sisi tu kuzungushwa yao kama walikuwa uppercase au lowercase.

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You guys hisia nzuri kuhusu hili?

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Jisikie huru nakala hii nyumbani, kuchukua hiyo,

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kulinganisha kwa nini wewe guys aliandika.

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Dhahiri kujisikia huru na kutuma maswali kuhusu hilo pia.

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Na tena, kutambua kwamba lengo hapa na tatizo lako unaweka

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si kupata wewe guys kuandika code kamilifu kwa seti yako tatizo.

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Ni uzoefu wa kujifunza. Yeah.

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>> Rudi do wakati kitanzi, kama ni sawa null,

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hivyo null tu ina maana chochote, wao tu enter?

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Null ni maalum pointer thamani,

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na sisi kutumia null wakati tunataka kusema

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tuna variable pointer kwamba ni akizungumzia chochote.

192
00:12:23,000 --> 00:12:28,000
Na hivyo kwa kawaida maana yake ni kwamba hii variable, hii variable ujumbe

193
00:12:28,000 --> 00:12:35,000
ni tupu, na hapa, kwa sababu sisi ni kutumia CS50 maalum string aina,

194
00:12:35,000 --> 00:12:37,000
kile ni CS50 string aina?

195
00:12:37,000 --> 00:12:42,000
Umeona nini ni wakati Daudi vunjwa nyuma Hood katika hotuba?

196
00:12:42,000 --> 00:12:44,000
Ni funky-ni pointer, haki?

197
00:12:44,000 --> 00:12:48,000
Okay, yeah. >> Ni * Char.

198
00:12:48,000 --> 00:12:52,000
Na hivyo kweli sisi inaweza kuchukua nafasi hii

199
00:12:52,000 --> 00:12:56,000
hapa hapa na ujumbe Char *,

200
00:12:56,000 --> 00:13:04,000
na hivyo kazi GetString, ikiwa haina mafanikio kupata kamba kutoka kwa mtumiaji,

201
00:13:04,000 --> 00:13:08,000
haiwezi Hazrat kamba, na kesi moja ambayo haiwezi Hazrat string

202
00:13:08,000 --> 00:13:11,000
ni kama mtumiaji aina ya mwisho wa faili tabia, D kudhibiti,

203
00:13:11,000 --> 00:13:17,000
ambayo si kitu kwa kawaida wewe kufanya, lakini kama kwamba hutokea

204
00:13:17,000 --> 00:13:20,000
basi kazi hii atarudi thamani null kama njia ya kusema

205
00:13:20,000 --> 00:13:23,000
"Hey, sikuweza kupata kamba."

206
00:13:23,000 --> 00:13:27,000
Nini kingetokea kama hatuwezi kuweka ujumbe = null,

207
00:13:27,000 --> 00:13:30,000
ambayo ni kitu ambacho sisi si kufanya bado?

208
00:13:30,000 --> 00:13:32,000
Mbona ingekuwa kwamba kuwa tatizo hapa?

209
00:13:32,000 --> 00:13:38,000
Kwa sababu najua kwamba sisi aliyesema kidogo katika hotuba kuhusu uvujaji kumbukumbu.

210
00:13:38,000 --> 00:13:42,000
Yeah, hebu kufanya hivyo, na hebu angalia nini kinatokea.

211
00:13:42,000 --> 00:13:44,000
>> Swali Basil ilikuwa kile kinachotokea kama sisi si kweli kuwa

212
00:13:44,000 --> 00:13:48,000
ujumbe huu = null mtihani?

213
00:13:48,000 --> 00:13:51,000
Hebu kitabu juu kwa juu.

214
00:13:51,000 --> 00:13:53,000
You guys unaweza maoni hii nje.

215
00:13:53,000 --> 00:13:55,000
Kweli, mimi itabidi kuokoa ni katika marekebisho.

216
00:13:55,000 --> 00:13:58,000
Hii itakuwa Revision 3.

217
00:13:58,000 --> 00:14:02,000
Nini wewe itabidi kufanya kuendesha mpango huu ni itabidi bonyeza hii icon gia juu hapa,

218
00:14:02,000 --> 00:14:04,000
na itabidi kuongeza hoja hiyo.

219
00:14:04,000 --> 00:14:10,000
Itabidi kutoa hoja muhimu tangu tunataka kupitisha hoja katika mstari amri.

220
00:14:10,000 --> 00:14:13,000
Hapa nina kwenda kuwapa namba 3. Mimi kama 3.

221
00:14:13,000 --> 00:14:19,000
Sasa zooming nyuma nje, mbio mpango.

222
00:14:19,000 --> 00:14:24,000
Ni mbio, kuandaa, kujenga.

223
00:14:24,000 --> 00:14:27,000
Hapa sisi kwenda. Ni kusubiri ilisababisha.

224
00:14:27,000 --> 00:14:33,000
Kama mimi aina katika kitu kama hujambo-wapi kwamba kwenda?

225
00:14:33,000 --> 00:14:38,000
Oh, mpango wangu alichukua muda mrefu sana na kukimbia. Mimi nilikuwa jawing kwa muda mrefu mno.

226
00:14:38,000 --> 00:14:40,000
Hapa unaendelea.

227
00:14:40,000 --> 00:14:43,000
Sasa ninapoandika katika hello.

228
00:14:43,000 --> 00:14:46,000
Tunaona kwamba encrypts ipasavyo.

229
00:14:46,000 --> 00:14:52,000
Sasa kile kinachotokea kama sisi kufanya GetString haraka kurudi null?

230
00:14:52,000 --> 00:14:57,000
Kumbuka, mimi alisema kwamba sisi alifanya hivyo na uendelezaji wa kudhibiti D kwa wakati mmoja.

231
00:14:57,000 --> 00:14:59,000
Mimi itabidi kitabu juu hapa. Tutaweza kukimbia tena.

232
00:14:59,000 --> 00:15:01,000
Ujenzi. Kuna unaendelea.

233
00:15:01,000 --> 00:15:04,000
Sasa wakati mimi hit kudhibiti D

234
00:15:04,000 --> 00:15:12,000
I got line hii kwamba anasema opt/sandbox50/bin/run.sh, Mkato kosa.

235
00:15:12,000 --> 00:15:15,000
Je, guys kuonekana kwamba kabla?

236
00:15:15,000 --> 00:15:17,000
>> [Mwanafunzi] Kwa nini kuna hakuna >> Samahani?

237
00:15:17,000 --> 00:15:20,000
[Mwanafunzi] Kwa nini kuna hakuna dampo msingi katika kesi hii?

238
00:15:20,000 --> 00:15:26,000
dampo msingi ni-swali ni kwa nini kuna hakuna dampo msingi hapa?

239
00:15:26,000 --> 00:15:29,000
Swali ni kwamba kuna inaweza kuwa, lakini dampo msingi ni faili

240
00:15:29,000 --> 00:15:31,000
kwamba anapata kuhifadhiwa kwenye gari ngumu.

241
00:15:31,000 --> 00:15:34,000
Katika kesi hii tumekuwa walemavu madampo ya msingi

242
00:15:34,000 --> 00:15:37,000
kwenye server kukimbia ili sisi hawana watu seg faulting

243
00:15:37,000 --> 00:15:40,000
na kujenga tani ya madampo ya msingi.

244
00:15:40,000 --> 00:15:46,000
Lakini unaweza kupata mmoja.

245
00:15:46,000 --> 00:15:48,000
Core dumps ni aina ya kitu kwamba mara nyingi unaweza Disable,

246
00:15:48,000 --> 00:15:52,000
na wakati mwingine unaweza kufanya.

247
00:15:52,000 --> 00:15:55,000
kosa segmentation, kwa kujibu swali lako, Basil,

248
00:15:55,000 --> 00:16:00,000
ni kusema kwamba sisi walijaribu kupata pointer

249
00:16:00,000 --> 00:16:05,000
kwamba alikuwa si kuweka kwa uhakika na kitu chochote.

250
00:16:05,000 --> 00:16:09,000
Kumbuka Binky katika video wakati Binky anajaribu

251
00:16:09,000 --> 00:16:12,000
kwenda kupata pointer kwamba si akizungumzia chochote?

252
00:16:12,000 --> 00:16:16,000
Katika kesi hiyo mimi nadhani kitaalam pointer ni akizungumzia kitu.

253
00:16:16,000 --> 00:16:20,000
Ni akizungumzia null, ambayo ni ya kitaalam 0,

254
00:16:20,000 --> 00:16:25,000
lakini kwamba ni defined kuwa katika sehemu ambayo si ya kupatikana

255
00:16:25,000 --> 00:16:28,000
na mpango wako, ili kupata kosa segmentation

256
00:16:28,000 --> 00:16:31,000
kwa sababu wewe si kupata kumbukumbu hiyo katika sehemu halali

257
00:16:31,000 --> 00:16:38,000
kama sehemu ya chungu au sehemu ya stack au sehemu data.

258
00:16:38,000 --> 00:16:40,000
Cool.

259
00:16:40,000 --> 00:16:48,000
Maswali yoyote zaidi kuhusu Kaisari?

260
00:16:48,000 --> 00:16:51,000
>> Hebu hoja juu. Hebu tuangalie Revision 2 kweli haraka.

261
00:16:51,000 --> 00:17:00,000
Hiyo Vigenère.

262
00:17:00,000 --> 00:17:04,000
Hapa katika Vigenère

263
00:17:04,000 --> 00:17:06,000
tutaweza kutembea kwa njia moja hii pretty haraka kwa sababu, tena,

264
00:17:06,000 --> 00:17:10,000
Vigenère na Kaisari ni sawa kabisa.

265
00:17:10,000 --> 00:17:12,000
Header maoni ni kabla,

266
00:17:12,000 --> 00:17:17,000
# Define ni kabla ili kuepuka kutumia namba hizi uchawi.

267
00:17:17,000 --> 00:17:21,000
Jambo zuri ni kusema sisi alitaka hoja ya

268
00:17:21,000 --> 00:17:23,000
alfabeti tofauti au kitu kama hicho.

269
00:17:23,000 --> 00:17:26,000
Badala ya kuwa na kwenda manually mabadiliko 26 wote katika code

270
00:17:26,000 --> 00:17:30,000
tungebadili hii hadi 27 au kuacha ni chini

271
00:17:30,000 --> 00:17:34,000
kama tungetumia alphabets tofauti, lugha mbalimbali.

272
00:17:34,000 --> 00:17:38,000
Tena, sisi tumepewa hii hundi ya kuhesabu hoja,

273
00:17:38,000 --> 00:17:42,000
na kwa kweli unaweza karibu kuchukua hii kama template.

274
00:17:42,000 --> 00:17:46,000
Pretty sana kila mpango kuandika wanapaswa kuwa-

275
00:17:46,000 --> 00:17:50,000
kama inachukua mstari amri hoja-baadhi mlolongo wa mistari

276
00:17:50,000 --> 00:17:55,000
kwamba anasoma kama hii katika mwanzo sana.

277
00:17:55,000 --> 00:17:59,000
Hiyo ni moja ya vipimo kwanza sanity unataka kufanya.

278
00:17:59,000 --> 00:18:03,000
>> Hapa nini hatukuwa ilikuwa sisi alifanya kwamba uhakika

279
00:18:03,000 --> 00:18:06,000
Keyword ilikuwa halali, na kwamba alikuwa hundi ya pili ambayo sisi alivyofanya.

280
00:18:06,000 --> 00:18:11,000
Ona tena kwamba sisi waliojitenga hii kutoka argc na 2.

281
00:18:11,000 --> 00:18:14,000
Kumbuka kwamba katika kesi hii jambo moja kwamba sisi na kufanya ni badala

282
00:18:14,000 --> 00:18:18,000
ya kutumia kwa i tulitaka validate string nzima,

283
00:18:18,000 --> 00:18:21,000
na ili kufanya hivyo kwa kweli kuwa na tabia ya kwenda kwa tabia

284
00:18:21,000 --> 00:18:23,000
juu ya kamba.

285
00:18:23,000 --> 00:18:29,000
Hakuna njia nzuri kuwaita kitu juu yake

286
00:18:29,000 --> 00:18:31,000
sababu hata, kwa mfano, i atarudi 0

287
00:18:31,000 --> 00:18:37,000
kama hawezi kuchanganua integer, hivyo kwamba hana hata kazi.

288
00:18:37,000 --> 00:18:42,000
Tena, nice ujumbe kuwaambia user hasa ni nini kilichotokea.

289
00:18:42,000 --> 00:18:45,000
Ndipo hapa, tena, sisi pia kushughulikia kesi ambapo

290
00:18:45,000 --> 00:18:50,000
user aina katika tabia kudhibiti D random.

291
00:18:50,000 --> 00:18:54,000
>> Na kisha Charlotte alikuwa swali mapema kuhusu jinsi sisi kusimamia ruka nafasi

292
00:18:54,000 --> 00:18:57,000
katika kamba yetu hapa.

293
00:18:57,000 --> 00:19:00,000
Hii ilikuwa ni aina ya sawa na kile sisi alivyofanya kwa mpango Myspace

294
00:19:00,000 --> 00:19:04,000
kwamba sisi tulikuwa katika sehemu, na njia hii kazi

295
00:19:04,000 --> 00:19:08,000
ni kwamba sisi kupatikana idadi ya herufi kwamba sisi d kuonekana.

296
00:19:08,000 --> 00:19:13,000
Kama sisi kutembea juu ya kamba ujumbe, kama sisi kutembea juu ya tabia na tabia,

297
00:19:13,000 --> 00:19:16,000
sisi kupatikana index kama sehemu ya yetu kwa kitanzi, na kisha sisi pia kupatikana

298
00:19:16,000 --> 00:19:21,000
idadi ya herufi, hivyo wahusika zisizo maalum, mashirika yasiyo ya tarakimu, mashirika yasiyo ya nyeupe nafasi

299
00:19:21,000 --> 00:19:27,000
kwamba sisi d kuonekana katika variable tofauti.

300
00:19:27,000 --> 00:19:33,000
Na kisha ufumbuzi hii hugeuza ufunguo

301
00:19:33,000 --> 00:19:41,000
kupata halisi muhimu integer, na ni gani kwamba juu ya kuruka,

302
00:19:41,000 --> 00:19:47,000
haki kabla basi huenda encrypt halisi ujumbe tabia.

303
00:19:47,000 --> 00:19:50,000
Kuna baadhi ya ufumbuzi ambao walikuwa kikamilifu kubwa mno

304
00:19:50,000 --> 00:19:58,000
kwamba ingekuwa kurekebisha muhimu juu wakati wa kupima kwa uhalali ufunguo wa.

305
00:19:58,000 --> 00:20:01,000
Mbali na kuhakikisha kwamba tabia na Keyword

306
00:20:01,000 --> 00:20:05,000
ilikuwa tabia kialfabeti pia akageuka kuwa katika integer

307
00:20:05,000 --> 00:20:13,000
katika mbalimbali 0-25 kwa basi ruka kuwa na kufanya kwamba baadaye katika hii kwa kitanzi.

308
00:20:13,000 --> 00:20:18,000
Tena, unaweza kuona hapa hii ni kweli exact code

309
00:20:18,000 --> 00:20:22,000
kwamba sisi kutumika katika Kaisari katika hatua hii.

310
00:20:22,000 --> 00:20:25,000
Unafanya exact kitu, hivyo hila halisi ni kuhesabia

311
00:20:25,000 --> 00:20:30,000
jinsi ya kugeuka Keyword katika integer.

312
00:20:30,000 --> 00:20:35,000
>> Jambo moja kwamba sisi tulikuwa hapa, ambayo ni kidogo mnene

313
00:20:35,000 --> 00:20:39,000
ni sisi amerudia maneno, Nadhani unaweza simu yake,

314
00:20:39,000 --> 00:20:45,000
3 tofauti mara juu ya mistari 58, 59, na 61.

315
00:20:45,000 --> 00:20:52,000
Je, mtu kueleza nini hasa maneno hii haina?

316
00:20:52,000 --> 00:20:55,000
Ni kupata tabia, kama wewe alisema.

317
00:20:55,000 --> 00:20:59,000
Yeah, ni [inaudible] tabia katika Keyword,

318
00:20:59,000 --> 00:21:04,000
na hivyo ni idadi ya herufi kuonekana kwa sababu wewe ni kusonga tu pamoja

319
00:21:04,000 --> 00:21:06,000
Keyword mara moja wewe ve kuona barua,

320
00:21:06,000 --> 00:21:10,000
ili kwenda kwa ufanisi ruka nafasi na mambo kama hayo.

321
00:21:10,000 --> 00:21:12,000
Yeah, kwa uhakika.

322
00:21:12,000 --> 00:21:16,000
Na kisha mara moja wewe ve kuonekana tupu Keyword wewe tu Mod hivyo hoja nyuma kote.

323
00:21:16,000 --> 00:21:18,000
Hasa. Hiyo ni maelezo kamilifu.

324
00:21:18,000 --> 00:21:23,000
Nini Kevin alisema ni kwamba tunataka index katika Keyword.

325
00:21:23,000 --> 00:21:28,000
Tunataka kupata tabia num_letters_seen, kama wewe,

326
00:21:28,000 --> 00:21:32,000
lakini kama num_letters_seen unazidi urefu wa Keyword,

327
00:21:32,000 --> 00:21:37,000
njia ya sisi kupata nyuma katika mbalimbali sahihi ni sisi kutumia operator Mod

328
00:21:37,000 --> 00:21:40,000
kwa ufanisi wrap karibu.

329
00:21:40,000 --> 00:21:43,000
Kwa mfano, kama katika muda mfupi, Keyword yetu ni Bacon,

330
00:21:43,000 --> 00:21:46,000
na ni 5 barua kwa muda mrefu.

331
00:21:46,000 --> 00:21:50,000
Lakini tumeona barua 6 katika maandishi yetu wazi katika hatua hii

332
00:21:50,000 --> 00:21:52,000
na encrypted 6.

333
00:21:52,000 --> 00:21:57,000
Sisi kuishia kupata num_letters_seen,

334
00:21:57,000 --> 00:22:00,000
ambayo ni 6, Mod urefu wa Keyword, 5,

335
00:22:00,000 --> 00:22:04,000
na hivyo tutaweza kupata 1, na hivyo kile tutaweza kufanya ni tutaweza

336
00:22:04,000 --> 00:22:14,000
kupata kwanza tabia ndani ya Keyword yetu katika hatua hiyo.

337
00:22:14,000 --> 00:22:21,000
>> Haki zote, maswali yoyote juu ya Vigenère

338
00:22:21,000 --> 00:22:26,000
kabla hatujaendelea?

339
00:22:26,000 --> 00:22:31,000
You guys hisia nzuri kuhusu hili?

340
00:22:31,000 --> 00:22:35,000
Cool, kubwa.

341
00:22:35,000 --> 00:22:38,000
Mimi nataka kuhakikisha kuwa wewe guys ni kupata nafasi ya kuona code

342
00:22:38,000 --> 00:22:48,000
kwamba sisi kufikiri inaonekana nzuri na kuwa na nafasi ya kujifunza kutoka humo.

343
00:22:48,000 --> 00:22:53,000
Hii ni kwenda kuwa mwisho tutaweza kutumia nafasi kwa wakati kuwa,

344
00:22:53,000 --> 00:22:59,000
na sisi ni kwenda mpito sasa, na mimi nina kwenda kwa cs50.net/lectures

345
00:22:59,000 --> 00:23:06,000
ili tuweze kufanya kidogo ya mapitio chemsha bongo.

346
00:23:06,000 --> 00:23:10,000
njia bora nadhani kuanza kufanya quiz mapitio

347
00:23:10,000 --> 00:23:15,000
ni kuja ukurasa huu Mihadhara, cs50.net/lectures,

348
00:23:15,000 --> 00:23:20,000
na chini ya kila wiki ya vichwa, hivyo kama mimi kuangalia hapa katika mkutano wa Wiki 0,

349
00:23:20,000 --> 00:23:27,000
Mimi naona kwamba tuna orodha ya mada ambazo sisi kufunikwa katika Wiki 0.

350
00:23:27,000 --> 00:23:31,000
>> Kama yoyote ya mada hizi wanaonekana unfamiliar na wewe

351
00:23:31,000 --> 00:23:34,000
wewe utakuwa dhahiri wanataka kwenda nyuma na scour maelezo hotuba na uwezekano

352
00:23:34,000 --> 00:23:39,000
hata skim kupitia mihadhara, kuangalia yao tena kama unataka

353
00:23:39,000 --> 00:23:44,000
kupata kujisikia kwa nini kinaendelea kwa kila mada hizo.

354
00:23:44,000 --> 00:23:49,000
Nasema kuongeza hii ya mwaka mmoja wa rasilimali baridi sisi tumepewa

355
00:23:49,000 --> 00:23:55,000
ni hizi Shorts kwamba tumekuwa umba, na kama ukiangalia Wiki 0,

356
00:23:55,000 --> 00:24:00,000
hatuna yote ya mada mifuniko, lakini sisi tumepewa chache kabisa wao,

357
00:24:00,000 --> 00:24:03,000
baadhi ya wale wa trickier, hivyo kuangalia Shorts haya tena

358
00:24:03,000 --> 00:24:08,000
ni njia nzuri ya kupata wewe juu kwa kasi.

359
00:24:08,000 --> 00:24:15,000
Hasa, mimi naenda kuweka kuziba kwa 3 juu ya chini, tangu mimi hizo.

360
00:24:15,000 --> 00:24:20,000
Lakini kama wewe ni ikikabiliwa na binary, bits, hex, kwamba aina ya mambo,

361
00:24:20,000 --> 00:24:22,000
binary ni sehemu kubwa ya kuanza.

362
00:24:22,000 --> 00:24:25,000
ASCII ni mtu mwingine kwamba ni vizuri kuona pia.

363
00:24:25,000 --> 00:24:31,000
Unaweza hata kuangalia yangu katika kasi 1.5x ikiwa mimi nina kwenda polepole mno kwa ajili yenu.

364
00:24:31,000 --> 00:24:35,000
Tangu mapitio yake, jisikie huru kufanya hivyo.

365
00:24:35,000 --> 00:24:40,000
>> Tu kuanza kweli haraka, sisi ni kwenda kupitia michache ya matatizo haya Jaribio

366
00:24:40,000 --> 00:24:44,000
tu kwa haraka churn kupitia haya.

367
00:24:44,000 --> 00:24:50,000
Kwa mfano, hebu tuangalie tatizo 16 kwamba mimi nimepata kulia hadi hapa kwenye bodi.

368
00:24:50,000 --> 00:24:54,000
Sisi tumepewa hii hesabu zifuatazo katika binary,

369
00:24:54,000 --> 00:24:56,000
na tunataka kuonyesha kazi yoyote.

370
00:24:56,000 --> 00:24:59,000
Sawa, mimi naenda kutoa hii risasi.

371
00:24:59,000 --> 00:25:01,000
You guys inapaswa kufuata pamoja na karatasi,

372
00:25:01,000 --> 00:25:04,000
na tutaweza kufanya hii kweli haraka.

373
00:25:04,000 --> 00:25:06,000
Tunataka kufanya hesabu zifuatazo katika binary.

374
00:25:06,000 --> 00:25:16,000
Mimi nimepata 00,110,010.

375
00:25:16,000 --> 00:25:27,000
Na mimi nina kwenda kuongeza ni 00,110,010.

376
00:25:27,000 --> 00:25:30,000
Kwa math akili maalum kufuatia pamoja nyumbani,

377
00:25:30,000 --> 00:25:35,000
hii ni ufanisi kuzidisha kwa 2.

378
00:25:35,000 --> 00:25:37,000
Hebu kuanza.

379
00:25:37,000 --> 00:25:39,000
Sisi ni kwenda kufuata huo Aidha algorithm kwamba sisi kufanya

380
00:25:39,000 --> 00:25:43,000
wakati sisi kuongeza idadi decimal pamoja.

381
00:25:43,000 --> 00:25:46,000
Kweli tofauti tu hapa ni kwamba sisi kitanzi nyuma kote

382
00:25:46,000 --> 00:25:51,000
mara moja tuna 1 + 1 badala ya mara moja sisi kupata 10.

383
00:25:51,000 --> 00:25:53,000
>> Kama sisi kuanza kutoka kulia, kweli haraka, nini tarakimu ya kwanza?

384
00:25:53,000 --> 00:25:55,000
[Mwanafunzi] 0. >> [Nate H.] 0.

385
00:25:55,000 --> 00:25:58,000
Mkuu, tarakimu ya pili?

386
00:25:58,000 --> 00:26:00,000
[Mwanafunzi] 1.

387
00:26:00,000 --> 00:26:02,000
[Nate H.] Je, ni 1? 1 + 1 ni?

388
00:26:02,000 --> 00:26:04,000
[Mwanafunzi] 10.

389
00:26:04,000 --> 00:26:08,000
[Nate H.] Hasa, ili kile ni tarakimu kwamba mimi kuandika kulia chini ndio 2 aliongeza pamoja?

390
00:26:08,000 --> 00:26:11,000
[Mwanafunzi] 1, 0, 0 au na kisha kubeba 1.

391
00:26:11,000 --> 00:26:15,000
[Nate H.] 0 na kubeba 1, hasa.

392
00:26:15,000 --> 00:26:18,000
Next moja juu, Basil, uko juu.

393
00:26:18,000 --> 00:26:20,000
Nini tatu >> [Basil] 1?.

394
00:26:20,000 --> 00:26:23,000
[Nate H.] 1, kamilifu. Kevin?

395
00:26:23,000 --> 00:26:27,000
[Kevin] 0. >> [Nate H.] 0, Charlotte?

396
00:26:27,000 --> 00:26:30,000
[Charlotte] 0. >> [Nate H.] Yeah, na nini mimi?

397
00:26:30,000 --> 00:26:32,000
[Mwanafunzi] 1.

398
00:26:32,000 --> 00:26:34,000
[Nate H.] Na nini mimi? Na kisha mimi kubeba 1.

399
00:26:34,000 --> 00:26:36,000
Perfect, Sahb? >> [Sahb] Sasa una 1.

400
00:26:36,000 --> 00:26:40,000
[Nate H.] Na kufanya mimi kufanya kitu chochote hapa?

401
00:26:40,000 --> 00:26:43,000
[Sahb] Kisha kwa moja ijayo una 1 kwa sababu wewe ulichukua zaidi ya 1.

402
00:26:43,000 --> 00:26:49,000
[Nate H.] Mkuu, hivyo hapa tunaweza kumaliza it up.

403
00:26:49,000 --> 00:26:51,000
Cool.

404
00:26:51,000 --> 00:26:54,000
[Mwanafunzi] Je 0 + 0 0 =?

405
00:26:54,000 --> 00:26:56,000
0 + 0 = 0.

406
00:26:56,000 --> 00:27:01,000
1 + 1, kama wewe alisema, ni 10, au 1, 0, badala.

407
00:27:01,000 --> 00:27:07,000
10 ni misnomer sababu mimi 10 ina maana idadi 10,

408
00:27:07,000 --> 00:27:12,000
na ni quirk ya jinsi sisi ni anayewakilisha wakati sisi ni kuandika yake.

409
00:27:12,000 --> 00:27:20,000
Sisi kuwakilisha idadi 2 kwa 1, 0, na namba 10 ni tofauti kidogo.

410
00:27:20,000 --> 00:27:23,000
>> Nini aina ya nice kuhusu binary ni kwamba kuna kweli ni kwamba wengi

411
00:27:23,000 --> 00:27:25,000
kesi unahitaji kujifunza.

412
00:27:25,000 --> 00:27:30,000
Kuna 0 + 0 = 0, 0 + 1 = 1,

413
00:27:30,000 --> 00:27:34,000
1 + 1 ni 0, na kisha kubeba 1,

414
00:27:34,000 --> 00:27:37,000
na kisha unaweza kuona hapa katika safu ya tatu kutoka kulia

415
00:27:37,000 --> 00:27:40,000
tulikuwa na hii 1, 1, na 1.

416
00:27:40,000 --> 00:27:43,000
Na 1 + 1 + 1 ni 1,

417
00:27:43,000 --> 00:27:45,000
na wewe kubeba mwingine 1.

418
00:27:45,000 --> 00:27:48,000
Wakati unafanya Aidha binary, pretty rahisi.

419
00:27:48,000 --> 00:27:51,000
Ningependa kufanya zaidi ya wanandoa wa haya sanity kuangalia wenyewe

420
00:27:51,000 --> 00:27:54,000
kabla ya kwenda huko kwa sababu hii ni

421
00:27:54,000 --> 00:28:00,000
pengine kitu kwamba tutaweza kuona kwenye chemsha bongo.

422
00:28:00,000 --> 00:28:03,000
Sasa hebu kufanya hili moja ijayo pia.

423
00:28:03,000 --> 00:28:06,000
Hebu kufanya tatizo 17.

424
00:28:06,000 --> 00:28:12,000
Sisi ni kwenda kubadilisha zifuatazo binary idadi decimal.

425
00:28:12,000 --> 00:28:28,000
Mimi nimepata 10100111001.

426
00:28:28,000 --> 00:28:33,000
Kumbuka katika video binary kwamba sikuwa

427
00:28:33,000 --> 00:28:36,000
Mimi nilitembea michache mifano, na mimi ilionyesha jinsi

428
00:28:36,000 --> 00:28:41,000
kila kitu kazi wakati wewe kufanya hivyo katika decimal.

429
00:28:41,000 --> 00:28:45,000
Wakati wewe ni kufanya kazi katika uwakilishi decimal Nadhani tuko

430
00:28:45,000 --> 00:28:48,000
katika hatua hii katika maisha yetu hivyo ufasaha katika kuwa

431
00:28:48,000 --> 00:28:53,000
ni pretty rahisi na Gloss juu ya mechanics ya jinsi kweli kazi.

432
00:28:53,000 --> 00:28:59,000
>> Lakini kwa kufanya recap haraka, kama mimi kuwa na idadi 137

433
00:28:59,000 --> 00:29:06,000
kweli hii ina maana-na tena, hii ni katika decimal uwakilishi-

434
00:29:06,000 --> 00:29:19,000
idadi 137 katika decimal inamaanisha kwamba nina 1 x 100 + 3 x 10 + 7 x 1.

435
00:29:19,000 --> 00:29:22,000
Hii yote ni kukaa kwenye screen.

436
00:29:22,000 --> 00:29:29,000
Na kisha kama ukiangalia namba hizi haki hapa,

437
00:29:29,000 --> 00:29:34,000
100, 10 na 1, unaweza kuona kwamba wao ni kweli nguvu zote za 10.

438
00:29:34,000 --> 00:29:43,000
Nina 10 ², 10 ¹, na 10 kwa sifuri.

439
00:29:43,000 --> 00:29:48,000
Tuna aina sawa ya kitu katika binary,

440
00:29:48,000 --> 00:29:55,000
isipokuwa kwamba msingi wetu, kama sisi kuiita, ni 2 badala ya 10.

441
00:29:55,000 --> 00:29:58,000
Hizi 10s kwamba mimi aliandika chini hapa chini,

442
00:29:58,000 --> 00:30:02,000
hii ² 10, 10 ¹, 10 hadi sifuri, 10 ni msingi wetu,

443
00:30:02,000 --> 00:30:08,000
na exponent, 0, 1, au 2,

444
00:30:08,000 --> 00:30:14,000
kimetajwa na nafasi ya tarakimu katika idadi hiyo sisi kuandika.

445
00:30:14,000 --> 00:30:21,000
1, kama sisi kuangalia saa hiyo, hii ni katika nafasi 1 2.

446
00:30:21,000 --> 00:30:27,000
3 ni katika nafasi ya 1, na ni katika nafasi ya 7 0.

447
00:30:27,000 --> 00:30:35,000
Hiyo ni jinsi sisi kupata mashujaa chini mbalimbali kwa ajili ya besi wetu.

448
00:30:35,000 --> 00:30:40,000
>> Kufuatia hii yote we'll-kweli, unajua nini?

449
00:30:40,000 --> 00:30:43,000
Tutaweza kufanya-wapi wangu tengua kifungo kwenda?

450
00:30:43,000 --> 00:30:45,000
Kuna unaendelea.

451
00:30:45,000 --> 00:30:47,000
I love this tengua kitu.

452
00:30:47,000 --> 00:30:51,000
Kufuatia hali hii nadhani kwa ajili yangu angalau

453
00:30:51,000 --> 00:30:54,000
Njia rahisi kuanza kuwabadili idadi binary

454
00:30:54,000 --> 00:30:57,000
au idadi hexadesimoli ambapo msingi ni 16

455
00:30:57,000 --> 00:31:02,000
na si 10 au 2 ni kwa kwenda mbele na kuandika

456
00:31:02,000 --> 00:31:09,000
besi na mashujaa kwa wote wa namba katika namba yangu binary kwa juu.

457
00:31:09,000 --> 00:31:14,000
Kama sisi kuanza kutoka kushoto kwenda kulia tena,

458
00:31:14,000 --> 00:31:17,000
ambayo ni aina ya counterintuitive,

459
00:31:17,000 --> 00:31:23,000
Mimi umebadirisha nyuma mweusi hapa, tuna 2 kwa nafasi 0,

460
00:31:23,000 --> 00:31:27,000
na kisha tuna 2 ¹, 2 ²,

461
00:31:27,000 --> 00:31:33,000
na kisha 2-3, 2-4, 2-5, 6,

462
00:31:33,000 --> 00:31:39,000
7, 8, 9, na 10.

463
00:31:39,000 --> 00:31:41,000
Hizi namba I ve yameandikwa nje ni mashujaa wote.

464
00:31:41,000 --> 00:31:48,000
Mimi niliandika tu besi hapa katika 3 kwanza tu kwa nafasi.

465
00:31:48,000 --> 00:31:50,000
>> Katika hatua hii mimi nina kwenda mbele na mimi nina kweli kwenda kufuta

466
00:31:50,000 --> 00:31:53,000
mambo ambayo sisi tulikuwa katika decimal, ikiwa hiyo ni sawa.

467
00:31:53,000 --> 00:31:57,000
Ve got kwamba wote.

468
00:31:57,000 --> 00:32:05,000
Wale wa wewe kuangalia online mimi nina uhakika utakuwa na uwezo wa rewind yangu kama Ningependa.

469
00:32:05,000 --> 00:32:07,000
Byte nyuma kalamu.

470
00:32:07,000 --> 00:32:12,000
Sasa, nini tunaweza kufanya-kama wewe guys si kabisa juu kwa kasi juu ya nguvu yako ya 2,

471
00:32:12,000 --> 00:32:15,000
hiyo kabisa cool.

472
00:32:15,000 --> 00:32:18,000
Hutokea. Mimi kuelewa.

473
00:32:18,000 --> 00:32:23,000
Mimi mara moja alikuwa mahojiano ya kazi ambapo Niliambiwa mimi wanapaswa kujua nguvu zote za 2

474
00:32:23,000 --> 00:32:26,000
juu kupitia 2 hadi 30.

475
00:32:26,000 --> 00:32:29,000
Haikuwa kazi mimi got.

476
00:32:29,000 --> 00:32:32,000
Anyway, you guys unaweza kwenda mbele na kufanya hesabu hapa,

477
00:32:32,000 --> 00:32:35,000
lakini kwa binary ni kweli haina mantiki,

478
00:32:35,000 --> 00:32:38,000
na wala haina mantiki kwa decimal au hexadesimoli aidha,

479
00:32:38,000 --> 00:32:43,000
kufanya math nje ambapo una zeros.

480
00:32:43,000 --> 00:32:49,000
Unaweza kuona nina 0 hapa, hapa 0, 0 hapa, hapa 0, 0 hapa, 0 hapa.

481
00:32:49,000 --> 00:32:52,000
Kwa nini wapate kuwa si mantiki ya kufanya math halisi

482
00:32:52,000 --> 00:32:56,000
mahesabu ya uwezo mwafaka wa 2 kwa nafasi hiyo?

483
00:32:56,000 --> 00:32:59,000
Hasa, kama Charlotte alisema, itakuwa ni 0.

484
00:32:59,000 --> 00:33:05,000
Ili kama vile kujiokoa wakati ikiwa kuhesabu mamlaka ya 2 ni si suti yako imara.

485
00:33:05,000 --> 00:33:10,000
Katika kesi hii sisi tu haja kwa mahesabu yake kwa 2-0 ambayo ni-?

486
00:33:10,000 --> 00:33:12,000
[Mwanafunzi] 1.

487
00:33:12,000 --> 00:33:14,000
[Nate H.] 1, 2-3 ambayo ni-?

488
00:33:14,000 --> 00:33:16,000
[Mwanafunzi] 8. >> [Nate H.] 8.

489
00:33:16,000 --> 00:33:18,000
2-4?

490
00:33:18,000 --> 00:33:21,000
[Mwanafunzi] 2. Samahani, 1.

491
00:33:21,000 --> 00:33:26,000
[Nate H.] 2-4 ni 16, kwa usahihi.

492
00:33:26,000 --> 00:33:28,000
2-5, Kevin >> 32?.

493
00:33:28,000 --> 00:33:32,000
[Nate H.] 32, 2-8?

494
00:33:32,000 --> 00:33:38,000
[Mwanafunzi] 32 x 8, 256.

495
00:33:38,000 --> 00:33:41,000
[Nate H.] Perfect.

496
00:33:41,000 --> 00:33:43,000
Na 2-10?

497
00:33:43,000 --> 00:33:45,000
[Mwanafunzi] 1024.

498
00:33:45,000 --> 00:33:49,000
[Nate H.] Yeah, 1024.

499
00:33:49,000 --> 00:33:57,000
>> Mara sisi tumepewa namba hizi tunaweza kuhitimisha yao yote juu.

500
00:33:57,000 --> 00:34:01,000
Na hii ni pale ambapo kwa kweli ni muhimu kufanya mambo kadhaa.

501
00:34:01,000 --> 00:34:07,000
Moja ni kwenda polepole na kuangalia kazi zenu.

502
00:34:07,000 --> 00:34:10,000
Unaweza kuwaambia kwamba kuna 1 mwishoni ya idadi hii,

503
00:34:10,000 --> 00:34:15,000
hivyo mimi lazima dhahiri kupata idadi isiyo ya kawaida kama matokeo yangu,

504
00:34:15,000 --> 00:34:18,000
kwa sababu wale wengine wote ni kwenda kuwa hata idadi

505
00:34:18,000 --> 00:34:21,000
kutokana na kwamba ni idadi binary.

506
00:34:21,000 --> 00:34:24,000
Kitu nyingine ya kufanya ni kama kupata na hatua hii ya mtihani

507
00:34:24,000 --> 00:34:27,000
na wewe ve yameandikwa nje hii mbali

508
00:34:27,000 --> 00:34:30,000
na wewe ni muda umeisha

509
00:34:30,000 --> 00:34:33,000
kuangalia idadi ya pointi kwamba tatizo hili ni ya thamani.

510
00:34:33,000 --> 00:34:40,000
Tatizo hili, kama unaweza kuona-kama mimi flip nyuma mbali yangu kweli haraka-

511
00:34:40,000 --> 00:34:44,000
tatizo hili ni thamani ya pointi 2, hivyo hii ni si aina ya Aidha

512
00:34:44,000 --> 00:34:47,000
unapaswa kwenda kwa kama wewe ni kweli taabu kwa muda.

513
00:34:47,000 --> 00:34:52,000
Lakini tutaweza kubadili nyuma kwa iPad, na tutaweza kwenda kwa njia hiyo kweli haraka.

514
00:34:52,000 --> 00:34:54,000
>> Mimi kama kufanya idadi ndogo ya kwanza

515
00:34:54,000 --> 00:34:56,000
kwa sababu mimi sioni kwamba rahisi.

516
00:34:56,000 --> 00:35:00,000
Mimi kama 32 na 8 kwa sababu wao kwenda pamoja pretty urahisi, na sisi kupata 50.

517
00:35:00,000 --> 00:35:03,000
16 na 1 anapata 17.

518
00:35:03,000 --> 00:35:05,000
Kuna sisi kupata 57,

519
00:35:05,000 --> 00:35:14,000
na basi tunaweza kufanya mapumziko ya hii, ili tuweze kufanya 57, 156.

520
00:35:14,000 --> 00:35:16,000
Kuja juu.

521
00:35:16,000 --> 00:35:19,000
Man, vizuri, hebu angalia.

522
00:35:19,000 --> 00:35:27,000
Tulikuwa na 57, 256, na 1024.

523
00:35:27,000 --> 00:35:31,000
Katika hatua hii, nisingependa tu kwenda kupitia.

524
00:35:31,000 --> 00:35:35,000
Sina kidokezo. Mimi wazi haja ya kusoma juu ya hili.

525
00:35:35,000 --> 00:35:40,000
7, 6, na 4, unaweza kupata 17.

526
00:35:40,000 --> 00:35:42,000
1, 5, 5, 2, 13.

527
00:35:42,000 --> 00:35:45,000
Kisha sisi kupata 3, na kisha sisi kupata 1.

528
00:35:45,000 --> 00:35:52,000
1337.

529
00:35:52,000 --> 00:35:55,000
Pasaka yai, mtu yeyote?

530
00:35:55,000 --> 00:35:59,000
Anybody kutambua idadi hii?

531
00:35:59,000 --> 00:36:02,000
Chris inatambua idadi. Ina maana gani, Chris?

532
00:36:02,000 --> 00:36:04,000
[Chris] Leet.

533
00:36:04,000 --> 00:36:11,000
Leet, hivyo kama wewe kuangalia hii, inaonekana kama leet.

534
00:36:11,000 --> 00:36:15,000
Hacker stuff. Jihadharini na kwamba aina ya mambo ya midterm au chemsha bongo, badala.

535
00:36:15,000 --> 00:36:19,000
Kama unaweza kuona kwamba aina ya mambo na wewe wanashangaa "huh,"

536
00:36:19,000 --> 00:36:22,000
kwamba ili kweli maana kitu.

537
00:36:22,000 --> 00:36:24,000
Mimi sijui. Daudi anapenda kuweka in

538
00:36:24,000 --> 00:36:26,000
Ni njia nzuri ya sanity kuangalia ni.

539
00:36:26,000 --> 00:36:30,000
Kama sawa, siwezi kuona nini kinaendelea.

540
00:36:30,000 --> 00:36:34,000
>> Hiyo Wiki 0/Week 1 stuff.

541
00:36:34,000 --> 00:36:39,000
Kama sisi kubadili nyuma kwa mbali wetu sasa,

542
00:36:39,000 --> 00:36:46,000
zoom nje, na michache ya mambo mengine.

543
00:36:46,000 --> 00:36:50,000
Kuna ASCII, ambayo tumekuwa kufanya mengi ya pamoja na seti tatizo.

544
00:36:50,000 --> 00:36:55,000
Dhana hii ya mtaji A. Je, ni kweli kwamba?

545
00:36:55,000 --> 00:36:57,000
Kujua ni integer decimal.

546
00:36:57,000 --> 00:37:00,000
65 ni nini ni mapped katika meza ASCII,

547
00:37:00,000 --> 00:37:03,000
na kwamba kwa hiyo jinsi ya kompyuta anaiandika,

548
00:37:03,000 --> 00:37:06,000
na kwamba ni jinsi gani tumekuwa kupata mbali kwa kweli kuandika

549
00:37:06,000 --> 00:37:09,000
mji mkuu wa tabia na tabia Herufi za chini

550
00:37:09,000 --> 00:37:14,000
katika baadhi ya hawa ufumbuzi na seti tatizo kwamba tumekuwa kufanya.

551
00:37:14,000 --> 00:37:16,000
michache ya mambo mengine.

552
00:37:16,000 --> 00:37:25,000
Sisi tumepewa kauli, misemo bulin hali,, tanzi, vigezo na threads.

553
00:37:25,000 --> 00:37:29,000
>> Wale wote wanaonekana kufanya akili kwa sehemu kubwa?

554
00:37:29,000 --> 00:37:35,000
Baadhi ya hii ni istilahi funky kidogo mara kwa mara.

555
00:37:35,000 --> 00:37:46,000
Mimi kama kufikiri ya kauli kama kwa kitu zaidi sehemu ambayo inaishia semicolon.

556
00:37:46,000 --> 00:37:51,000
Kauli kama vile x = 7, ambayo unaweka variable,

557
00:37:51,000 --> 00:37:54,000
ikatengeneza kuitwa x = 7.

558
00:37:54,000 --> 00:38:01,000
Takribani x ni pia aina ya kuwa wanaweza kuhifadhi namba 7,

559
00:38:01,000 --> 00:38:05,000
hivyo ni int au uwezekano kuelea au mfupi au Char,

560
00:38:05,000 --> 00:38:07,000
kitu kama hicho.

561
00:38:07,000 --> 00:38:12,000
kujieleza bulin ni kutumia hizi mbili ni sawa na

562
00:38:12,000 --> 00:38:17,000
na bang sawa au si sawa, chini ya mkuu zaidi kuliko,

563
00:38:17,000 --> 00:38:22,000
chini ya au sawa na, aina ya mambo ambayo yote.

564
00:38:22,000 --> 00:38:28,000
Masharti basi ni kama mwingine kauli.

565
00:38:28,000 --> 00:38:32,000
Napenda tukumbuke kwamba huwezi kuwa na mwingine bila sambamba ikiwa.

566
00:38:32,000 --> 00:38:37,000
Aidha, huwezi kuwa na mwingine ikiwa bila sambamba ikiwa.

567
00:38:37,000 --> 00:38:40,000
Tanzi, kukumbuka aina 3 ya matanzi tumekuwa hammering katika wewe

568
00:38:40,000 --> 00:38:43,000
kwa michache ya mwisho ya sehemu na seti tatizo.

569
00:38:43,000 --> 00:38:46,000
Kutumia gani wakati wakati wewe ni kupata mtumiaji pembejeo,

570
00:38:46,000 --> 00:38:51,000
kutumia wakati matanzi mpaka hali fulani ni kweli,

571
00:38:51,000 --> 00:38:56,000
na kisha kwa kutumia wale kwa matanzi kama unahitaji

572
00:38:56,000 --> 00:39:01,000
kujua ambayo iteration ya kitanzi wewe ni sasa juu ya ni jinsi mimi kufikiri juu yake.

573
00:39:01,000 --> 00:39:07,000
Au kama wewe ni kufanya kwa ajili ya tabia ya kila katika string nataka kufanya jambo fulani,

574
00:39:07,000 --> 00:39:15,000
kwa kila kipengele katika safu nataka kufanya kitu kwa kipengele hicho.

575
00:39:15,000 --> 00:39:18,000
>> Threads na matukio.

576
00:39:18,000 --> 00:39:21,000
Haya sisi si kufunikwa hivyo waziwazi katika C,

577
00:39:21,000 --> 00:39:23,000
lakini kumbuka hii kutoka Scratch.

578
00:39:23,000 --> 00:39:26,000
Hii ni dhana ya kuwa na scripts tofauti.

579
00:39:26,000 --> 00:39:32,000
Hii pia ni wazo hili la utangazaji tukio hilo.

580
00:39:32,000 --> 00:39:37,000
Baadhi ya watu hawakutumia utangazaji katika miradi yao ya awali,

581
00:39:37,000 --> 00:39:40,000
ambayo ni kinyume kabisa ya baridi,

582
00:39:40,000 --> 00:39:46,000
lakini haya ni 2 njia tofauti za utunzaji suala hili kubwa iitwayo concurrency,

583
00:39:46,000 --> 00:39:49,000
ambayo ni jinsi gani unaweza kupata programu kutekeleza

584
00:39:49,000 --> 00:39:54,000
au inaonekana nitafanya wakati huo huo?

585
00:39:54,000 --> 00:39:59,000
Majukumu mbalimbali mbio wakati kazi nyingine pia mbio.

586
00:39:59,000 --> 00:40:01,000
Hii ni jinsi mfumo wa uendeshaji wako inaonekana kazi.

587
00:40:01,000 --> 00:40:04,000
Hii ni kwa nini hata kama, kwa mfano,

588
00:40:04,000 --> 00:40:10,000
Nimekuwa got browser yangu mbio, naweza pia kurejea kwenye Spotify na kucheza wimbo.

589
00:40:10,000 --> 00:40:14,000
Hiyo ni zaidi ya kitu dhana kuelewa.

590
00:40:14,000 --> 00:40:17,000
Napenda kuangalia threads mfupi

591
00:40:17,000 --> 00:40:21,000
kama Ningependa kujifunza zaidi juu ya hilo.

592
00:40:21,000 --> 00:40:26,000
>> Hebu angalia, naamini kuna yangaliweza

593
00:40:26,000 --> 00:40:31,000
tatizo juu ya hili katika moja ya hizi.

594
00:40:31,000 --> 00:40:35,000
Tena, nadhani threads na matukio ni si kitu ambacho tutakuwa tumemaliza katika C

595
00:40:35,000 --> 00:40:41,000
tu kwa sababu ni vigumu zaidi kuliko kiasi kikubwa katika Scratch.

596
00:40:41,000 --> 00:40:44,000
Unapaswa na wasiwasi kuhusu hilo pale, lakini dhahiri kuelewa dhana,

597
00:40:44,000 --> 00:40:47,000
kuelewa nini kinaendelea.

598
00:40:47,000 --> 00:40:52,000
Kabla hatujaendelea, maswali yoyote juu ya Wiki 0 nyenzo?

599
00:40:52,000 --> 00:40:55,000
Kila mtu hisia nzuri?

600
00:40:55,000 --> 00:41:03,000
Kuelewa vigezo na kile kutofautiana ni?

601
00:41:03,000 --> 00:41:08,000
>> Kuendelea. Wiki 1.

602
00:41:08,000 --> 00:41:12,000
michache ya mambo hapa kwamba walikuwa si hasa kufunikwa

603
00:41:12,000 --> 00:41:21,000
katika mapitio ya jaribio lazima na pia ni zaidi ya dhana mambo ya kufikiri juu.

604
00:41:21,000 --> 00:41:30,000
kwanza ni hii fikra ya nini chanzo code, watunzi na code kitu ni.

605
00:41:30,000 --> 00:41:32,000
Anybody? Basil.

606
00:41:32,000 --> 00:41:37,000
Ni kitu code-I mean chanzo code ni nini kuweka ndani ya Clang,

607
00:41:37,000 --> 00:41:42,000
na kitu code ni nini Clang unaweka nje ili kompyuta yako inaweza kusoma mpango.

608
00:41:42,000 --> 00:41:44,000
Hasa.

609
00:41:44,000 --> 00:41:47,000
Chanzo code ni code C kwamba kweli kuyaandika.

610
00:41:47,000 --> 00:41:50,000
Object code ni nini kupata nje ya Clang.

611
00:41:50,000 --> 00:41:54,000
Ni sekunde 0 na 1s katika muundo ambao binary.

612
00:41:54,000 --> 00:41:59,000
Kinachotokea ni wakati wewe kuwa na rundo la files kitu,

613
00:41:59,000 --> 00:42:04,000
wanasema wewe ni kuandaa mradi au mpango kwamba anatumia files nyingi chanzo code,

614
00:42:04,000 --> 00:42:09,000
ambayo kwa mkataba wanapewa c. faili ugani.

615
00:42:09,000 --> 00:42:13,000
Hiyo ndiyo sababu tuna caesar.c, vigenère.c.

616
00:42:13,000 --> 00:42:18,000
Kama wewe ni kuandika mipango Java kuwapa ugani java..

617
00:42:18,000 --> 00:42:24,000
Chatu programu ugani PY. Mara nyingi.

618
00:42:24,000 --> 00:42:26,000
>> Mara baada ya kuwa nyingi. Files c, wewe kukusanya yao.

619
00:42:26,000 --> 00:42:29,000
Clang mtemi yote hii Junk binary.

620
00:42:29,000 --> 00:42:33,000
Basi, kwa sababu wewe tu unataka 1 mpango

621
00:42:33,000 --> 00:42:37,000
una kiungo linker yote ya kitu hizi files pamoja

622
00:42:37,000 --> 00:42:40,000
ndani ya 1 faili la kutekelezwa.

623
00:42:40,000 --> 00:42:45,000
Hii pia ni kile kinachotokea wakati kutumia maktaba CS50, kwa mfano.

624
00:42:45,000 --> 00:42:50,000
Maktaba CS50 ni wote kwamba h header faili.

625
00:42:50,000 --> 00:42:53,000
kwamba kusoma, kwamba # includecs50.h.

626
00:42:53,000 --> 00:42:58,000
Na basi ni pia maalum binary maktaba faili

627
00:42:58,000 --> 00:43:02,000
hiyo imekuwa compiled kwamba ni sekunde 0 na 1s,

628
00:43:02,000 --> 00:43:08,000
na kwamba-l bendera, hivyo kama sisi kurudi nyuma kwa Spaces yetu na sisi kuangalia kweli haraka

629
00:43:08,000 --> 00:43:11,000
saa nini kinaendelea hapa wakati sisi kuangalia Clang amri yetu,

630
00:43:11,000 --> 00:43:15,000
kile tulichopata ni hii ni chanzo chetu code faili haki hapa.

631
00:43:15,000 --> 00:43:18,000
Hizi ni rundo la bendera compiler.

632
00:43:18,000 --> 00:43:22,000
Na kisha mwishoni sana, hawa-l bendera kiungo katika

633
00:43:22,000 --> 00:43:30,000
halisi binary files kwa maktaba hizi 2, maktaba na kisha CS50 maktaba math.

634
00:43:30,000 --> 00:43:35,000
>> Kuelewa kila aina ya madhumuni files '

635
00:43:35,000 --> 00:43:38,000
katika mchakato wa kutungwa ni kitu utasikia wanataka kuwa na uwezo wa

636
00:43:38,000 --> 00:43:43,000
kutoa angalau wa ngazi ya juu jumla ya.

637
00:43:43,000 --> 00:43:46,000
Chanzo code huja in code Object hutoka nje.

638
00:43:46,000 --> 00:43:53,000
Object code files zilizounganishwa pamoja, na wewe kupata nzuri, executable file.

639
00:43:53,000 --> 00:43:55,000
Cool.

640
00:43:55,000 --> 00:43:58,000
Hii pia ni wapi unaweza kupata makosa katika pointi nyingi

641
00:43:58,000 --> 00:44:00,000
katika mchakato wa kutungwa.

642
00:44:00,000 --> 00:44:04,000
Hii ni wapi, kwa mfano, kama wewe kuchukua nje hii bendera kuunganisha,

643
00:44:04,000 --> 00:44:10,000
Bendera CS50, na wewe ni katika omit Spaces au wakati wewe ni mbio code yako,

644
00:44:10,000 --> 00:44:13,000
hii ni wapi utasikia kupata kosa katika awamu ya kuunganisha,

645
00:44:13,000 --> 00:44:18,000
na linker watasema, "Hey, wewe kuitwa GetString kazi

646
00:44:18,000 --> 00:44:20,000
kwamba katika maktaba CS50. "

647
00:44:20,000 --> 00:44:25,000
"Wewe aliniambia ilikuwa katika maktaba CS50, na siwezi kupata code kwa hilo."

648
00:44:25,000 --> 00:44:28,000
Hiyo ambapo una kiungo katika, na kwamba ni tofauti

649
00:44:28,000 --> 00:44:33,000
kutoka makosa compiler sababu compiler ni kuangalia syntax na kwamba aina ya mambo ya ajabu.

650
00:44:33,000 --> 00:44:38,000
Ni vizuri kujua nini kinaendelea wakati.

651
00:44:38,000 --> 00:44:42,000
>> Mambo mengine kujua juu.

652
00:44:42,000 --> 00:44:49,000
Naweza kusema wewe dhahiri wanataka kuangalia mfupi juu typecasting kufanyika kwa Yordani

653
00:44:49,000 --> 00:44:55,000
kuelewa nini ints ni chini ya Hood,

654
00:44:55,000 --> 00:44:58,000
nini chars ni chini ya Hood.

655
00:44:58,000 --> 00:45:02,000
Tunapozungumzia kuhusu ASCII na sisi kweli kuangalia meza ASCII,

656
00:45:02,000 --> 00:45:07,000
kile ambacho kufanya anatupa chini ya kuangalia Hood

657
00:45:07,000 --> 00:45:13,000
jinsi ya kompyuta kweli inawakilisha mji mkuu na 7 tarakimu

658
00:45:13,000 --> 00:45:17,000
na comma na swali alama.

659
00:45:17,000 --> 00:45:20,000
kompyuta pia ana njia maalum kuwakilisha

660
00:45:20,000 --> 00:45:23,000
namba 7 kama integer.

661
00:45:23,000 --> 00:45:27,000
Ina njia maalum kuwakilisha namba 7 kama idadi floating uhakika,

662
00:45:27,000 --> 00:45:29,000
na wale ni tofauti sana.

663
00:45:29,000 --> 00:45:32,000
Typecasting ni jinsi kumweleza kompyuta "Hey, mimi nataka kubadili

664
00:45:32,000 --> 00:45:37,000
kutoka uwakilishi moja kwa uwakilishi mwingine. "

665
00:45:37,000 --> 00:45:40,000
Mbona sisi kuangalia kwamba.

666
00:45:40,000 --> 00:45:44,000
>> Napenda pia kuchukua kuangalia mfupi juu ya maktaba na fupi juu ya compilers.

667
00:45:44,000 --> 00:45:47,000
Wale majadiliano kuhusu mchakato wa utungaji,

668
00:45:47,000 --> 00:45:53,000
kile ni maktaba, na kwenda juu ya baadhi ya maswali haya kwamba unaweza kupata aliuliza.

669
00:45:53,000 --> 00:45:55,000
Maswali juu ya Wiki nyenzo 1?

670
00:45:55,000 --> 00:46:03,000
Je, kuna mada katika hapa kwamba wanaonekana daunting Ningependa cover?

671
00:46:03,000 --> 00:46:07,000
Mimi nina kujaribu pigo kupitia wengi wa mada hizi mapema ili tuweze kupata

672
00:46:07,000 --> 00:46:13,000
kuyatumia na kufanya kidogo ya recursion.

673
00:46:13,000 --> 00:46:15,000
Mawazo?

674
00:46:15,000 --> 00:46:19,000
Chochote ili kufidia?

675
00:46:19,000 --> 00:46:21,000
Wakati kwa baadhi chocolate labda?

676
00:46:21,000 --> 00:46:23,000
You guys ni kazi kwa njia hiyo.

677
00:46:23,000 --> 00:46:26,000
Mimi naenda kuweka sipping juu ya kahawa yangu.

678
00:46:26,000 --> 00:46:31,000
Wiki 2.

679
00:46:31,000 --> 00:46:34,000
Nzuri wito, nzuri wito.

680
00:46:34,000 --> 00:46:38,000
Katika Wiki 2 tuliongea kidogo zaidi juu ya kazi.

681
00:46:38,000 --> 00:46:43,000
>> Katika seti ya kwanza wachache tatizo sisi hawakuwa kweli kuandika kazi yoyote wakati wote

682
00:46:43,000 --> 00:46:45,000
nyingine kuliko ambayo kazi?

683
00:46:45,000 --> 00:46:47,000
[Mwanafunzi] Kuu. >> Kuu, hasa.

684
00:46:47,000 --> 00:46:51,000
Na hivyo tumeona kwamba mavazi tofauti kuu wears.

685
00:46:51,000 --> 00:46:54,000
Kuna moja ambayo inachukua hoja hakuna,

686
00:46:54,000 --> 00:46:58,000
na sisi tu kusema utupu katika kati ya mabano,

687
00:46:58,000 --> 00:47:01,000
na kisha kuna mtu mwingine ambapo sisi kufanya wanataka kuchukua hoja mstari amri,

688
00:47:01,000 --> 00:47:08,000
na kama tuliona, hiyo ambapo una argc int na kamba argv safu

689
00:47:08,000 --> 00:47:13,000
au sasa kwamba tumekuwa wazi kweli string kuwa * Char kwamba ni

690
00:47:13,000 --> 00:47:20,000
sisi ni kwenda kuanza kuandika ni kama Char * argv na kisha mabano.

691
00:47:20,000 --> 00:47:22,000
Katika Tatizo Set 3, you guys alipoona rundo ya utendaji,

692
00:47:22,000 --> 00:47:27,000
na wewe kutekelezwa rundo la kazi, kuteka, kuangalia juu, kinyang'anyiro.

693
00:47:27,000 --> 00:47:31,000
prototypes walikuwa yote yaliyoandikwa pale kwa ajili yenu.

694
00:47:31,000 --> 00:47:33,000
>> Nini nilitaka kuzungumzia hapa na kazi kweli haraka

695
00:47:33,000 --> 00:47:38,000
ni kwamba kuna sehemu 3 kwao wakati wowote wewe kuandika kazi.

696
00:47:38,000 --> 00:47:43,000
Una bayana aina ya kurudi kwa kazi.

697
00:47:43,000 --> 00:47:46,000
Una kubainisha jina kwa ajili ya kazi, na kisha una bayana

698
00:47:46,000 --> 00:47:51,000
orodha hoja au orodha parameter.

699
00:47:51,000 --> 00:47:57,000
Kwa mfano, kama ningekuwa kuandika kazi kwa jumla juu ya rundo la integers

700
00:47:57,000 --> 00:48:03,000
na kisha kurudi kwangu Jumla nini itakuwa marejeo yangu aina

701
00:48:03,000 --> 00:48:06,000
kama alitaka sum integers na kisha kurudi Jumla?

702
00:48:06,000 --> 00:48:12,000
Kisha jina la kazi.

703
00:48:12,000 --> 00:48:27,000
Kama mimi kwenda mbele na kuandika katika kijani, sehemu hii ni aina ya kurudi.

704
00:48:27,000 --> 00:48:34,000
Hii sehemu ni jina.

705
00:48:34,000 --> 00:48:40,000
Na kisha katika kati ya mabano

706
00:48:40,000 --> 00:48:46,000
ni ambapo mimi kutoa hoja,

707
00:48:46,000 --> 00:48:56,000
mara nyingi hufupishwa kama args, wakati mwingine inaitwa zilizounganishwa kwa vigezo.

708
00:48:56,000 --> 00:49:00,000
Na kama una moja, wewe tu kutaja moja.

709
00:49:00,000 --> 00:49:06,000
Kama una nyingi wewe kujitenga kila moja kwa koma.

710
00:49:06,000 --> 00:49:13,000
Na kwa hoja ya kila wewe kuwapa mambo ambayo ni 2-Kevin?

711
00:49:13,000 --> 00:49:18,000
[Kevin] Wewe kutoa aina na kisha jina.

712
00:49:18,000 --> 00:49:21,000
Na kisha jina, na jina ni jina kwamba utaenda kutumia

713
00:49:21,000 --> 00:49:25,000
kwa kutaja hoja kuwa ndani ya kazi jumla,

714
00:49:25,000 --> 00:49:27,000
ndani ya kazi kwamba wewe sasa kuandika.

715
00:49:27,000 --> 00:49:32,000
>> Huna kwa-kwa mfano, ikiwa mimi nina kwenda sum up,

716
00:49:32,000 --> 00:49:41,000
kusema, safu ya integers-we'll kufanya safu int,

717
00:49:41,000 --> 00:49:46,000
na mimi nitakupa mwenyewe braces baadhi curly kuna-

718
00:49:46,000 --> 00:49:51,000
basi wakati mimi kupita safu ya kazi Jumla

719
00:49:51,000 --> 00:49:55,000
Mimi kupita katika nafasi ya kwanza ya orodha hoja.

720
00:49:55,000 --> 00:49:59,000
Lakini safu kwamba mimi kupita katika hana kuwa arr jina.

721
00:49:59,000 --> 00:50:07,000
Arr ni kwenda kuwa jinsi mimi rejea hoja kuwa ndani ya mwili wa kazi.

722
00:50:07,000 --> 00:50:10,000
Kitu nyingine kwamba tunahitaji kuchukua katika akaunti,

723
00:50:10,000 --> 00:50:14,000
na hii ni tofauti kidogo kutoka kazi, lakini nadhani ni hatua muhimu,

724
00:50:14,000 --> 00:50:20,000
ni kwamba katika C wakati mimi nina maandishi kazi kama hii

725
00:50:20,000 --> 00:50:29,000
jinsi gani mimi kujua jinsi wengi mambo ni katika safu hii?

726
00:50:29,000 --> 00:50:31,000
Hii ni kiasi fulani ya swali hila.

727
00:50:31,000 --> 00:50:35,000
Kuongelea hii kidogo kidogo katika sehemu ya mwisho wa wiki.

728
00:50:35,000 --> 00:50:40,000
Nitajuaje idadi ya vipengele ndani ya safu katika C?

729
00:50:40,000 --> 00:50:44,000
Je, kuna njia?

730
00:50:44,000 --> 00:50:49,000
>> Ni zinageuka kuwa hakuna njia ya kujua.

731
00:50:49,000 --> 00:50:52,000
Una kupita katika tofauti.

732
00:50:52,000 --> 00:50:55,000
Kuna hila ambayo unaweza kufanya

733
00:50:55,000 --> 00:51:00,000
kama wewe ni katika kazi moja katika safu ambayo imekuwa alitangaza,

734
00:51:00,000 --> 00:51:04,000
na wewe ni kufanya kazi pamoja na safu stack.

735
00:51:04,000 --> 00:51:06,000
Lakini hiyo kazi tu kama wewe ni katika kazi moja.

736
00:51:06,000 --> 00:51:09,000
Mara baada ya kupita safu ya kazi nyingine au kama umefanya alitangaza safu

737
00:51:09,000 --> 00:51:12,000
na wewe kuweka kwamba safu juu ya chungu, umetumia malloc

738
00:51:12,000 --> 00:51:15,000
 na kwamba aina ya mambo, basi wote Bets ni mbali.

739
00:51:15,000 --> 00:51:18,000
Kisha wewe kweli kuwa kupita kote

740
00:51:18,000 --> 00:51:21,000
hoja maalum au mwingine parameter

741
00:51:21,000 --> 00:51:23,000
ninawaambieni jinsi kubwa ni safu.

742
00:51:23,000 --> 00:51:28,000
Katika kesi hiyo, ningependa wanataka kutumia comma-I'm sorry, ni kwenda mbali screen hapa-

743
00:51:28,000 --> 00:51:32,000
na ningependa kupita katika hoja nyingine

744
00:51:32,000 --> 00:51:40,000
 na simu yake int len ​​kwa urefu.

745
00:51:40,000 --> 00:51:44,000
>> Jambo moja kwamba wanaweza kuja juu ya jaribio

746
00:51:44,000 --> 00:51:49,000
inakuomba kuandika au kutekeleza kazi fulani kuitwa kitu.

747
00:51:49,000 --> 00:51:54,000
Kama hatuwezi kukupa mfano, ili jambo hili zima hapa,

748
00:51:54,000 --> 00:51:58,000
fujo hii yote inaitwa tamko kazi au mfano kazi,

749
00:51:58,000 --> 00:52:01,000
hii ni moja ya mambo ya kwanza utasikia wanataka msumari chini kama si kupewa

750
00:52:01,000 --> 00:52:03,000
na wewe haki ya mbali juu ya chemsha bongo.

751
00:52:03,000 --> 00:52:06,000
hila nyingine mimi wameweza kujifunza ni kwamba

752
00:52:06,000 --> 00:52:11,000
wanasema sisi kufanya kukupa mfano kwa ajili ya kazi, na sisi kusema, "Hey, nimepata kuandika."

753
00:52:11,000 --> 00:52:16,000
Ndani ya braces curly kwamba una juu ya jaribio

754
00:52:16,000 --> 00:52:20,000
ikiwa utaona kwamba kuna aina kurudi na taarifa kwamba aina ya kurudi

755
00:52:20,000 --> 00:52:25,000
ni kitu kingine zaidi ya batili, ambayo ina maana kwamba kazi haina kurudi kitu chochote,

756
00:52:25,000 --> 00:52:28,000
basi jambo moja dhahiri wanataka kufanya ni kuandika

757
00:52:28,000 --> 00:52:33,000
baadhi ya aina ya kauli kurudi mwishoni sana ya kazi.

758
00:52:33,000 --> 00:52:40,000
Kurudi, na katika kesi hii, tutaweza kuweka tupu kwa sababu tunataka kujaza tupu.

759
00:52:40,000 --> 00:52:44,000
Lakini hii anapata wewe kufikiri katika njia ya haki kuhusu jinsi mimi kwenda kwa mbinu na tatizo hili?

760
00:52:44,000 --> 00:52:49,000
Na ni kuwakumbusha utaenda kuwa na kurudi thamani

761
00:52:49,000 --> 00:52:51,000
kwa mpigaji wa kazi.

762
00:52:51,000 --> 00:52:54,000
>> Yeah. >> [Mwanafunzi] Je style kuomba wakati sisi ni kuandika code juu ya chemsha bongo?

763
00:52:54,000 --> 00:52:58,000
Vile kama indentation na kwamba aina ya stuff? >> [Mwanafunzi] Yeah.

764
00:52:58,000 --> 00:53:00,000
Hapana, si kama mengi.

765
00:53:00,000 --> 00:53:09,000
Nadhani mengi ya-hii ni kitu tutaweza kufafanua juu ya chemsha bongo juu ya siku ya,

766
00:53:09,000 --> 00:53:15,000
lakini kwa kawaida ni pamoja na hofu juu ya # na kwamba aina ya mambo, ni aina ya nje.

767
00:53:15,000 --> 00:53:17,000
[Mwanafunzi] Je, unahitaji kutoa maoni yako code handwritten?

768
00:53:17,000 --> 00:53:19,000
Je, unahitaji kutoa maoni yako code handwritten?

769
00:53:19,000 --> 00:53:24,000
Akizungumza daima ni nzuri kama una wasiwasi kuhusu mikopo ubaguzi

770
00:53:24,000 --> 00:53:29,000
au unataka kuwasiliana dhamira yako kwa grader.

771
00:53:29,000 --> 00:53:33,000
Lakini mimi, tena, utathibitisha juu ya chemsha bongo yenyewe na juu ya siku quiz,

772
00:53:33,000 --> 00:53:39,000
lakini mimi siamini kwamba utahitajika kuandika maoni, hakuna.

773
00:53:39,000 --> 00:53:42,000
Kawaida si, lakini ni dhahiri aina ya kitu ambapo

774
00:53:42,000 --> 00:53:45,000
unaweza kuelezea nia yako, kama "Hey, hii ni pale ambapo mimi nina kwenda kwa hayo."

775
00:53:45,000 --> 00:53:49,000
Na wakati mwingine ambayo inaweza kusaidia kwa mikopo ubaguzi.

776
00:53:49,000 --> 00:53:51,000
Cool.

777
00:53:51,000 --> 00:53:53,000
>> Basil.

778
00:53:53,000 --> 00:53:56,000
[Basil] Nini tofauti kati ya kutangaza, kusema, int lang

779
00:53:56,000 --> 00:54:03,000
katika hoja au vigezo dhidi ya kutangaza variable ndani ya kazi?

780
00:54:03,000 --> 00:54:05,000
Wow, kahawa akashuka windpipe.

781
00:54:05,000 --> 00:54:07,000
[Basil] Kama ambavyo mambo sisi tunataka kuweka katika hoja.

782
00:54:07,000 --> 00:54:09,000
Yeah, hiyo ni swali kubwa.

783
00:54:09,000 --> 00:54:11,000
Jinsi gani unaweza kuchagua nini mambo unataka kuweka katika hoja

784
00:54:11,000 --> 00:54:17,000
dhidi ya mambo unapaswa kufanya ndani ya kazi?

785
00:54:17,000 --> 00:54:24,000
Katika kesi hii sisi ni pamoja na wawili hawa kama hoja

786
00:54:24,000 --> 00:54:29,000
kwa sababu wao ni kitu ambacho yeyote ataenda kutumia kazi Jumla

787
00:54:29,000 --> 00:54:32,000
inahitaji bayana mambo hayo.

788
00:54:32,000 --> 00:54:35,000
>> kazi Jumla, kama kuongelea, hana njia ya kujua

789
00:54:35,000 --> 00:54:40,000
jinsi kubwa ni safu anapata kutoka mpigaji wake au mwenye kutumia kazi jibu.

790
00:54:40,000 --> 00:54:44,000
Ina hakuna njia ya kujua jinsi kubwa safu kwamba ni.

791
00:54:44,000 --> 00:54:48,000
sababu sisi kupita katika urefu haki hii hapa kama hoja

792
00:54:48,000 --> 00:54:51,000
ni kwa sababu hiyo ni kitu ambacho sisi ni kimsingi kuwaambia mpigaji wa kazi,

793
00:54:51,000 --> 00:54:55,000
yeyote ataenda kutumia kazi jumla, "Hey, si tu una kutupa safu

794
00:54:55,000 --> 00:54:59,000
ya ints, wewe pia kutuambia jinsi kubwa safu kwamba ve ametupa ni. "

795
00:54:59,000 --> 00:55:03,000
[Basil] Wale wote wawili kuwa amri line hoja?

796
00:55:03,000 --> 00:55:06,000
Hapana, hawa ni halisi hoja kwamba ungependa kupita kwa kazi.

797
00:55:06,000 --> 00:55:10,000
>> Hebu kufanya ukurasa mpya hapa.

798
00:55:10,000 --> 00:55:13,000
[Basil] Kama jina ingekuwa kupita-

799
00:55:13,000 --> 00:55:24,000
[Nate H.] Kama mimi na int kuu (utupu),

800
00:55:24,000 --> 00:55:27,000
na mimi naenda kuweka katika kurudi 0 yangu hapa chini kwa chini,

801
00:55:27,000 --> 00:55:31,000
na kusema nataka kuita kazi jibu.

802
00:55:31,000 --> 00:55:42,000
Mimi nataka kusema int x = Jumla ();

803
00:55:42,000 --> 00:55:46,000
Kutumia kazi Jumla nina kupita katika safu wote kwamba mimi nataka jumla juu

804
00:55:46,000 --> 00:55:51,000
na urefu wa safu, hivyo hii ni mahali ambapo

805
00:55:51,000 --> 00:55:54,000
kuchukua nilikuwa safu ya ints,

806
00:55:54,000 --> 00:56:12,000
kusema nilikuwa int numbaz [] = 1, 2, 3,

807
00:56:12,000 --> 00:56:16,000
aina ya matumizi ya kwamba hacked up syntax haki pale,

808
00:56:16,000 --> 00:56:21,000
kisha kile atafanya ni katika jumla napenda nataka kupita katika

809
00:56:21,000 --> 00:56:27,000
wote numbaz na namba 3

810
00:56:27,000 --> 00:56:30,000
kuwaambia kazi Jumla "Okay, hapa safu Mimi nataka wewe sum."

811
00:56:30,000 --> 00:56:34,000
"Hapa ni kawaida yake."

812
00:56:34,000 --> 00:56:39,000
Je, hiyo mantiki? Je, hiyo kujibu swali lako?

813
00:56:39,000 --> 00:56:42,000
>> Kwa njia nyingi ni gani sambamba nini tuko kufanya na kuu

814
00:56:42,000 --> 00:56:44,000
wakati tuna hoja mstari amri.

815
00:56:44,000 --> 00:56:47,000
mpango kama Kaisari cipher, kwa mfano, kwamba zinahitajika

816
00:56:47,000 --> 00:56:53,000
amri line hoja bila kuwa na uwezo wa kufanya chochote.

817
00:56:53,000 --> 00:56:57,000
Itakuwa si kujua jinsi ya encrypt kama hakuwa na kuwaambia ni nini muhimu ya kutumia

818
00:56:57,000 --> 00:57:03,000
au kama wewe hakumwambia ni nini string alitaka encrypt.

819
00:57:03,000 --> 00:57:08,000
Uvuvio kwa ajili ya pembejeo, hii ni mahali ambapo sisi tumepewa 2 taratibu mbalimbali

820
00:57:08,000 --> 00:57:14,000
kwa ajili ya kuchukua pembejeo katika kutoka kwa mtumiaji, kwa ajili ya kuchukua habari katika kutoka kwa mtumiaji.

821
00:57:14,000 --> 00:57:19,000
Kwa Matatizo Kuweka 1 tuliona hii GetInt, GetString, GetFloat njia

822
00:57:19,000 --> 00:57:26,000
ya uvuvio kwa ajili ya pembejeo, na kwamba wito kwa kutumia kiwango pembejeo mkondo.

823
00:57:26,000 --> 00:57:28,000
Ni tofauti kidogo.

824
00:57:28,000 --> 00:57:31,000
Ni kitu ambacho unaweza kufanya kwa wakati mmoja kama kinyume na

825
00:57:31,000 --> 00:57:35,000
wakati wewe waomba mpango, wakati wa kuanza mpango mbio.

826
00:57:35,000 --> 00:57:41,000
hoja mstari amri zote ni maalum wakati wa kuanza mbio mpango.

827
00:57:41,000 --> 00:57:47,000
Sisi tumekuwa kuchanganya mbili ya wale.

828
00:57:47,000 --> 00:57:52,000
Wakati sisi kutumia hoja ya kazi, ni kiasi kama hoja mstari amri kwa kuu.

829
00:57:52,000 --> 00:57:56,000
Ni wakati wewe waomba kazi unahitaji liambie

830
00:57:56,000 --> 00:58:05,000
nini hasa inahitaji ili kufanya kazi yake.

831
00:58:05,000 --> 00:58:08,000
Jambo jingine nzuri kuangalia-na mimi itabidi basi ukiangalia hiyo katika muda wako wa vipuri,

832
00:58:08,000 --> 00:58:11,000
na ilikuwa imefunikwa katika jaribio-ilikuwa wazo hili la wigo

833
00:58:11,000 --> 00:58:15,000
na mitaa vigezo dhidi ya vigezo kimataifa.

834
00:58:15,000 --> 00:58:18,000
Je, makini na hilo.

835
00:58:18,000 --> 00:58:23,000
>> Sasa kwamba sisi ni kupata juu ya mambo haya mengine,

836
00:58:23,000 --> 00:58:27,000
katika Wiki 3 tulipoanza kuzungumza kuhusu kutafuta na kuchagua.

837
00:58:27,000 --> 00:58:32,000
Kutafuta na kuchagua, angalau katika CS50,

838
00:58:32,000 --> 00:58:39,000
ni mengi sana kuanzishwa kwa baadhi ya sehemu zaidi ya nadharia ya sayansi ya kompyuta.

839
00:58:39,000 --> 00:58:42,000
tatizo la kutafuta, tatizo la kuchagua

840
00:58:42,000 --> 00:58:46,000
ni kubwa, kisheria matatizo.

841
00:58:46,000 --> 00:58:52,000
Jinsi gani unaweza kupata idadi fulani katika safu ya mabilioni ya integers?

842
00:58:52,000 --> 00:58:55,000
Jinsi gani unaweza kupata jina fulani ndani ya kitabu cha simu

843
00:58:55,000 --> 00:58:59,000
ambayo imehifadhiwa kwenye Laptop yako?

844
00:58:59,000 --> 00:59:04,000
Na hivyo kuanzisha wazo hili la mara asymptotic kukimbia

845
00:59:04,000 --> 00:59:11,000
kwa kweli kupima muda gani, jinsi ngumu tatizo haya ni,

846
00:59:11,000 --> 00:59:14,000
muda gani kuchukua kutatua.

847
00:59:14,000 --> 00:59:20,000
Katika, naamini, quiz 2011 humo, kuna tatizo kwamba nadhani mastahili

848
00:59:20,000 --> 00:59:27,000
kufunika kwa haraka sana, ambayo ni hii moja, tatizo 12.

849
00:59:27,000 --> 00:59:32,000
O hakuna, ni Omega.

850
00:59:32,000 --> 00:59:41,000
>> Hapa tunazungumzia muda wa kasi iwezekanavyo kukimbia

851
00:59:41,000 --> 00:59:46,000
kwa algorithm fulani na kisha slowest iwezekanavyo wakati kukimbia.

852
00:59:46,000 --> 00:59:52,000
Hii Omega na O ni kweli tu njia za mkato.

853
00:59:52,000 --> 00:59:55,000
Wao ni notational shortcuts kwa kusema

854
00:59:55,000 --> 00:59:59,000
jinsi ya kufunga katika kesi bora mapenzi algorithm wetu kukimbia,

855
00:59:59,000 --> 01:00:06,000
na jinsi polepole katika kesi mbaya zaidi kutokea itakuwa algorithm wetu kukimbia?

856
01:00:06,000 --> 01:00:10,000
Hebu kufanya michache ya haya, na haya pia yalipendekezwa

857
01:00:10,000 --> 01:00:13,000
katika muda mfupi juu ya nukuu asymptotic, ambayo mimi sana kupendekeza.

858
01:00:13,000 --> 01:00:17,000
Jackson alifanya kazi nzuri kwa kweli.

859
01:00:17,000 --> 01:00:23,000
Pamoja na tafuta binary, tunazungumzia kuhusu tafuta binary kama kuwa algorithm,

860
01:00:23,000 --> 01:00:28,000
na sisi kwa kawaida kuzungumza juu yake katika suala la O. yake kubwa

861
01:00:28,000 --> 01:00:30,000
Nini ni O kubwa?

862
01:00:30,000 --> 01:00:34,000
Nini ni madogo zaidi iwezekanavyo kukimbia wakati wa tafuta binary?

863
01:00:34,000 --> 01:00:36,000
[Mwanafunzi] N ²?

864
01:00:36,000 --> 01:00:41,000
Close, mimi nadhani sawa na kwamba.

865
01:00:41,000 --> 01:00:43,000
Ni mengi zaidi kuliko hiyo.

866
01:00:43,000 --> 01:00:45,000
[Mwanafunzi] binary? >> Yeah, binary tafuta.

867
01:00:45,000 --> 01:00:47,000
[Mwanafunzi] Ni logi n.

868
01:00:47,000 --> 01:00:49,000
Ingia n, hivyo nini kuingia n maana?

869
01:00:49,000 --> 01:00:51,000
Ni halves hivyo kila iteration.

870
01:00:51,000 --> 01:00:56,000
Hasa, hivyo katika kesi slowest inawezekana,

871
01:00:56,000 --> 01:01:00,000
kusema kama una safu sorted

872
01:01:00,000 --> 01:01:08,000
ya integers milioni na idadi wewe ni kuangalia kwa

873
01:01:08,000 --> 01:01:14,000
aidha ni kipengele sana kwanza katika safu au kipengele sana mwisho katika safu.

874
01:01:14,000 --> 01:01:18,000
Kumbuka, binary tafuta algorithm kazi kwa kuangalia kipengele katikati,

875
01:01:18,000 --> 01:01:21,000
kuona kama kwamba ni mechi kwamba wewe ni kuangalia kwa.

876
01:01:21,000 --> 01:01:23,000
Kama ni, basi kubwa, wewe kupatikana.

877
01:01:23,000 --> 01:01:27,000
>> Katika kesi bora, jinsi ya kufunga haina binary tafuta kukimbia?

878
01:01:27,000 --> 01:01:29,000
[Wanafunzi] 1.

879
01:01:29,000 --> 01:01:32,000
1, ni mara kwa mara wakati, kubwa O ya 1. Yeah.

880
01:01:32,000 --> 01:01:36,000
[Mwanafunzi] nina swali. Wakati kusema logi ya n, maana kwa heshima na msingi 2, sawa?

881
01:01:36,000 --> 01:01:40,000
Ndiyo, hivyo hilo ni jambo nyingine.

882
01:01:40,000 --> 01:01:44,000
Sisi tunasema n logi, na mimi nadhani wakati mimi nilikuwa katika shule ya sekondari

883
01:01:44,000 --> 01:01:48,000
Mimi daima kudhani kuwa logi ilikuwa msingi 10.

884
01:01:48,000 --> 01:01:57,000
Yeah, hivyo ndiyo, ingia msingi 2 kawaida ni nini sisi kutumia.

885
01:01:57,000 --> 01:02:02,000
Tena, kurejea tafuta binary, kama wewe ni kwa ajili ya kutafuta ama

886
01:02:02,000 --> 01:02:05,000
kipengele mwishoni sana au kipengele katika mwanzo sana,

887
01:02:05,000 --> 01:02:08,000
kwa sababu ya kuanza katikati na kisha wewe Discard

888
01:02:08,000 --> 01:02:13,000
namna yoyote nusu haifikii vigezo kwamba wewe ni kuangalia kwa,

889
01:02:13,000 --> 01:02:15,000
na wewe uende kwa nusu ya pili na nusu ujao na nusu ijayo.

890
01:02:15,000 --> 01:02:19,000
Kama mimi nina kwa ajili ya kutafuta kipengele kubwa katika safu milioni integer

891
01:02:19,000 --> 01:02:25,000
Mimi naenda kupunguza nusu yake katika logi zaidi ya mara milioni 1

892
01:02:25,000 --> 01:02:28,000
kabla mimi hatimaye kupima na kuona kwamba kipengele nina kuangalia kwa

893
01:02:28,000 --> 01:02:33,000
ni katika kubwa au katika ripoti juu ya safu,

894
01:02:33,000 --> 01:02:38,000
na kwamba itachukua logi ya n, logi ya mara milioni 1.

895
01:02:38,000 --> 01:02:40,000
>> Bubble aina.

896
01:02:40,000 --> 01:02:43,000
Je guys kukumbuka aina Bubble algorithm?

897
01:02:43,000 --> 01:02:47,000
Kevin, unaweza kunipa recap ya haraka ya kile kilichotokea katika algorithm aina Bubble?

898
01:02:47,000 --> 01:02:50,000
[Kevin] Kimsingi huenda kwa njia ya kila kitu katika orodha.

899
01:02:50,000 --> 01:02:52,000
Inaangalia mbili kwanza.

900
01:02:52,000 --> 01:02:55,000
Kama moja ya kwanza ni kubwa kuliko ya pili ni swaps yao.

901
01:02:55,000 --> 01:02:58,000
Kisha inalinganishwa pili na wa tatu, kitu kimoja swaps,

902
01:02:58,000 --> 01:03:00,000
tatu na nne, kila njia ya chini.

903
01:03:00,000 --> 01:03:03,000
Bigger idadi kufuata hadi mwisho.

904
01:03:03,000 --> 01:03:07,000
Na baada ya matanzi hata hivyo wengi wewe ni kosa.

905
01:03:07,000 --> 01:03:11,000
Hasa, hivyo nini Kevin alisema ni kwamba tutaweza kuangalia idadi kubwa

906
01:03:11,000 --> 01:03:15,000
Bubble hadi mwisho wa safu.

907
01:03:15,000 --> 01:03:19,000
Kwa mfano, je, wewe akili kutembea kwetu kupitia mfano huu kama hii ni safu yetu?

908
01:03:19,000 --> 01:03:21,000
[Kevin] Wewe itabidi kuchukua 2 na 3.

909
01:03:21,000 --> 01:03:23,000
3 ni kubwa kuliko 2, hivyo byta yao.

910
01:03:23,000 --> 01:03:29,000
[Nate H.] sawa, hivyo sisi byta hizi, na hivyo kupata 2, 3, 6, 4, na 9.

911
01:03:29,000 --> 01:03:31,000
[Kevin] Kisha kulinganisha 3 na 6.

912
01:03:31,000 --> 01:03:33,000
3 ni ndogo kuliko 6, hivyo waache,

913
01:03:33,000 --> 01:03:37,000
na 6 na 4, wewe d byta yao kwa sababu 4 ni ndogo kuliko 6.

914
01:03:37,000 --> 01:03:42,000
[Nate H.] sawa, hivyo mimi kupata 2, 3, 4, 6, 9.

915
01:03:42,000 --> 01:03:46,000
[Kevin] Na 9 ni kubwa kuliko 6, hivyo kuondoka.

916
01:03:46,000 --> 01:03:48,000
Na wewe d kwenda nyuma kupitia tena.

917
01:03:48,000 --> 01:03:50,000
>> [Nate H.] Am I kufanyika katika hatua hii >> [Kevin] No?

918
01:03:50,000 --> 01:03:52,000
Na kwa nini mimi si kufanyika katika hatua hii?

919
01:03:52,000 --> 01:03:54,000
Kwa sababu inaonekana ni kama safu yangu ni Iliyopangwa. Mimi nina kuangalia saa yake.

920
01:03:54,000 --> 01:03:57,000
[Kevin] Nenda kwa njia hiyo tena na kuhakikisha kwamba hakuna zaidi swaps

921
01:03:57,000 --> 01:04:00,000
kabla unaweza kikamilifu kuacha.

922
01:04:00,000 --> 01:04:04,000
Hasa, hivyo unahitaji kuendelea kupitia na kuhakikisha kwamba hakuna swaps

923
01:04:04,000 --> 01:04:06,000
kwamba unaweza kufanya katika hatua hii.

924
01:04:06,000 --> 01:04:08,000
Ni kweli tu bahati, kama wewe alisema, kwamba sisi kuishia

925
01:04:08,000 --> 01:04:12,000
tu baada ya kufanya 1 kupita na sisi ni Iliyopangwa.

926
01:04:12,000 --> 01:04:16,000
Lakini kwa kufanya hii katika kesi ya jumla tutaweza kweli kufanya hii tena na tena.

927
01:04:16,000 --> 01:04:20,000
Na kwa kweli, hii ilikuwa mfano wa kesi bora iwezekanavyo,

928
01:04:20,000 --> 01:04:24,000
kama tulivyoona katika tatizo.

929
01:04:24,000 --> 01:04:28,000
Tuliona kwamba kesi bora ilikuwa n.

930
01:04:28,000 --> 01:04:32,000
Tulipitia wakati safu 1.

931
01:04:32,000 --> 01:04:35,000
Je, ni kesi mbaya zaidi kutokea kwa algorithm hii?

932
01:04:35,000 --> 01:04:37,000
[Kevin] N ².

933
01:04:37,000 --> 01:04:41,000
Na nini kuangalia kwamba kama? Nini kuangalia safu kama hiyo bila kuchukua n ² muda?

934
01:04:41,000 --> 01:04:43,000
[Kevin] [inaudible] Iliyopangwa.

935
01:04:43,000 --> 01:04:51,000
Hasa, hivyo kama mimi alikuwa na safu 9, 7, 6, 5, 2,

936
01:04:51,000 --> 01:04:54,000
kwanza 9 ingekuwa Bubble njia yote juu.

937
01:04:54,000 --> 01:04:59,000
Baada iteration 1 tunatarajia kuwa na 7, 6, 5, 2, 9.

938
01:04:59,000 --> 01:05:07,000
Kisha 7 ingekuwa tutuka, 6, 5, 2, 7, 9, na kadhalika na kadhalika.

939
01:05:07,000 --> 01:05:13,000
>> Tunatarajia kwenda kupitia safu nzima n nyakati,

940
01:05:13,000 --> 01:05:16,000
na unaweza kweli kupata kidogo sahihi zaidi kuliko huu

941
01:05:16,000 --> 01:05:23,000
sababu mara tumekuwa wakiongozwa 9 njia yote juu katika nafasi yake ya mwisho iwezekanavyo

942
01:05:23,000 --> 01:05:26,000
Tunajua kwamba sisi kamwe kuwa na kulinganisha dhidi ya kipengele kwamba tena.

943
01:05:26,000 --> 01:05:29,000
Mara sisi kuanza bubbling 7 hadi

944
01:05:29,000 --> 01:05:35,000
Tunajua kwamba sisi inaweza kuacha mara moja 7 ni sawa mbele ya 9

945
01:05:35,000 --> 01:05:37,000
tangu tumekuwa tayari ikilinganishwa 9 kwa hiyo.

946
01:05:37,000 --> 01:05:46,000
Kama wewe kufanya hili katika njia smart siyo kweli, mimi nadhani, kwamba muda kiasi.

947
01:05:46,000 --> 01:05:49,000
Wewe hutaenda kulinganisha inawezekana wote [inaudible] michanganyiko

948
01:05:49,000 --> 01:05:55,000
kila wakati kwenda kwa njia ya kila iteration.

949
01:05:55,000 --> 01:05:59,000
Lakini bado, tunapozungumzia amefungwa hii juu sisi kusema kwamba

950
01:05:59,000 --> 01:06:04,000
wewe ni kuangalia n ² kulinganisha wote njia ya kupitia.

951
01:06:04,000 --> 01:06:12,000
>> Hebu kwenda nyuma, na tangu tuko mapya ya kupata kidogo mfupi juu ya wakati

952
01:06:12,000 --> 01:06:15,000
Naweza kusema unapaswa dhahiri kupitia mapumziko ya meza hii,

953
01:06:15,000 --> 01:06:17,000
kujaza yote nje.

954
01:06:17,000 --> 01:06:20,000
Fikiria mifano. Fikiria mifano halisi.

955
01:06:20,000 --> 01:06:22,000
Hiyo ni kweli Handy na kusaidia kufanya.

956
01:06:22,000 --> 01:06:25,000
Atayateka.

957
01:06:25,000 --> 01:06:28,000
Hii ni aina ya meza hiyo kama kupitia katika sayansi ya kompyuta

958
01:06:28,000 --> 01:06:32,000
unapaswa kweli kuanza kujua haya moyo kwa.

959
01:06:32,000 --> 01:06:34,000
Hizi ni aina ya maswali ya kupata katika mahojiano.

960
01:06:34,000 --> 01:06:36,000
Hizi ni aina ya mambo ambayo ni vizuri kujua,

961
01:06:36,000 --> 01:06:41,000
na fikiria juu ya kesi hizo makali, kweli kuhesabia nje ya jinsi ya kufikiri juu ya

962
01:06:41,000 --> 01:06:45,000
tukijua kwamba kwa Bubble aina safu mbaya zaidi kutokea

963
01:06:45,000 --> 01:06:52,000
kuchambua na kwamba ni moja ambayo ili reverse.

964
01:06:52,000 --> 01:06:58,000
>> Kuyatumia. Hebu kuzungumza kidogo kuhusu kuyatumia.

965
01:06:58,000 --> 01:07:03,000
Katika dakika chache zilizopita sisi hapa

966
01:07:03,000 --> 01:07:11,000
Mimi najua hili ni jambo pamoja na faili I / O kwamba ni badala mpya.

967
01:07:11,000 --> 01:07:19,000
Tunapozungumzia kuhusu sababu kuyatumia tunataka kuzungumza juu ya kuyatumia

968
01:07:19,000 --> 01:07:24,000
ni kwa sababu, moja, wakati sisi ni kazi katika C

969
01:07:24,000 --> 01:07:33,000
sisi ni kweli katika ngazi ya haki ya chini ikilinganishwa na ya kisasa zaidi ya programu lugha.

970
01:07:33,000 --> 01:07:38,000
Sisi ni kweli na uwezo wa kuendesha vigezo katika kumbukumbu,

971
01:07:38,000 --> 01:07:43,000
takwimu nje ambapo ni kweli iko ndani ya RAM yetu.

972
01:07:43,000 --> 01:07:46,000
Mara ve gone juu ya kuchukua madarasa mfumo wa uendeshaji utaona

973
01:07:46,000 --> 01:07:48,000
kwamba hiyo ni, tena, aina ya matumizi.

974
01:07:48,000 --> 01:07:50,000
Hiyo si kweli kesi.

975
01:07:50,000 --> 01:07:52,000
Sisi tumepewa kumbukumbu virtual hiyo mafichoni wale maelezo kutoka kwetu.

976
01:07:52,000 --> 01:07:58,000
>> Lakini kwa sasa unaweza kudhani kwamba wakati una mpango,

977
01:07:58,000 --> 01:08:02,000
kwa mfano, wakati wa kuanza mbio yako Kaisari cipher mpango-

978
01:08:02,000 --> 01:08:06,000
Mimi itabidi kubadili nyuma kwa iPad wangu kweli haraka-

979
01:08:06,000 --> 01:08:12,000
kwamba katika mpango wa mwanzo yako, kama una, kusema,

980
01:08:12,000 --> 01:08:15,000
4 gigabytes ya RAM kwenye Laptop yako,

981
01:08:15,000 --> 01:08:21,000
kupata kuweka kando hii chunk, na tutaweza wito huu RAM.

982
01:08:21,000 --> 01:08:25,000
Na ni kuanza katika mahali tunakwenda kuwaita 0,

983
01:08:25,000 --> 01:08:30,000
na inaishia katika eneo ambalo Tutamwita gigabytes 4.

984
01:08:30,000 --> 01:08:37,000
Mimi kwa kweli hawezi kuandika. Mtu, kwamba ni hacked.

985
01:08:37,000 --> 01:08:40,000
Wakati mpango wako executes

986
01:08:40,000 --> 01:08:44,000
mfumo wa uendeshaji carves up RAM,

987
01:08:44,000 --> 01:08:51,000
na ni bayana makundi mbalimbali kwa ajili ya sehemu mbalimbali za programu yako ya kuishi ndani

988
01:08:51,000 --> 01:08:58,000
Chini hapa eneo hili ni aina ya nchi za mtu yeyote.

989
01:08:58,000 --> 01:09:02,000
Wakati wewe kwenda mbele kidogo hapa

990
01:09:02,000 --> 01:09:05,000
nimepata kweli mahali ambapo

991
01:09:05,000 --> 01:09:09,000
code kwa maisha yako mpango.

992
01:09:09,000 --> 01:09:13,000
Hiyo halisi code binary, faili kwamba executable kweli anapata kubeba katika kumbukumbu

993
01:09:13,000 --> 01:09:17,000
wakati kukimbia mpango, na anaishi katika sehemu code.

994
01:09:17,000 --> 01:09:22,000
Na kama programu yako executes processor inaangalia sehemu hii code

995
01:09:22,000 --> 01:09:24,000
kufikiri nini ni mafundisho ya pili?

996
01:09:24,000 --> 01:09:27,000
Je, ni line ya pili ya code nahitaji nitafanya?

997
01:09:27,000 --> 01:09:31,000
>> Kuna pia sehemu data, na hii ni mahali ambapo constants string wale

998
01:09:31,000 --> 01:09:34,000
kupata kuhifadhiwa kwamba tumekuwa kutumia.

999
01:09:34,000 --> 01:09:42,000
Na kisha mbali zaidi juu kuna hii sehemu iitwayo lundo.

1000
01:09:42,000 --> 01:09:46,000
Sisi kupata kumbukumbu katika huko kwa kutumia malloc,

1001
01:09:46,000 --> 01:09:49,000
na kisha kuelekea sana juu ya mpango wako

1002
01:09:49,000 --> 01:09:52,000
kuna stack,

1003
01:09:52,000 --> 01:09:57,000
na hiyo ambapo sisi tumekuwa kucheza kwa zaidi ya mwanzo.

1004
01:09:57,000 --> 01:09:59,000
Hii si kwa wadogo au kitu chochote.

1005
01:09:59,000 --> 01:10:03,000
mengi ya hii ni sana mashine tegemezi,

1006
01:10:03,000 --> 01:10:10,000
mfumo wa uendeshaji tegemezi, lakini hii ni kiasi gani mambo kupata chunked up.

1007
01:10:10,000 --> 01:10:17,000
Wakati wewe kukimbia na mpango na wewe kutangaza variable kuitwa x-

1008
01:10:17,000 --> 01:10:27,000
Mimi naenda kuteka mwingine sanduku chini chini, na hii itakuwa ni RAM pia.

1009
01:10:27,000 --> 01:10:29,000
Na mimi nina kwenda kuangalia.

1010
01:10:29,000 --> 01:10:34,000
Tutaweza kuchora mistari jagged kuonyesha hii ni tu sehemu ndogo ya RAM

1011
01:10:34,000 --> 01:10:38,000
na si wote ni kama sisi kuteka saa ya juu.

1012
01:10:38,000 --> 01:10:43,000
>> Kama mimi kutangaza variable integer kuitwa x,

1013
01:10:43,000 --> 01:10:49,000
basi nini mimi kweli kupata ni ramani

1014
01:10:49,000 --> 01:10:54,000
kwamba ni kuhifadhiwa katika meza ishara ya mpango wangu

1015
01:10:54,000 --> 01:11:00,000
kuwa unajumuisha x jina kwa eneo hili la kumbukumbu kwamba nimepata inayotolewa

1016
01:11:00,000 --> 01:11:03,000
haki hapa kati ya baa wima.

1017
01:11:03,000 --> 01:11:08,000
Kama mimi na mstari wa kanuni katika mpango wangu kwamba anasema x = 7

1018
01:11:08,000 --> 01:11:15,000
processor anajua "Oh, okay, najua kwamba x maisha katika eneo hili katika kumbukumbu."

1019
01:11:15,000 --> 01:11:25,000
"Mimi nina kwenda mbele na kuandika 7 huko."

1020
01:11:25,000 --> 01:11:28,000
Jinsi gani kujua nini eneo hili ni katika kumbukumbu?

1021
01:11:28,000 --> 01:11:30,000
Naam, kwamba ni yote kufanyika kwa wakati kukusanya.

1022
01:11:30,000 --> 01:11:34,000
compiler inachukua huduma ya kugawa ambapo kila moja ya vigezo ni kwenda

1023
01:11:34,000 --> 01:11:40,000
na kujenga ramani maalum au badala ya kuunganisha dots

1024
01:11:40,000 --> 01:11:43,000
kati ya alama na ambapo ni kwenda, variable ya jina

1025
01:11:43,000 --> 01:11:46,000
na ambapo ni kwenda kuishi katika kumbukumbu.

1026
01:11:46,000 --> 01:11:50,000
Lakini zinageuka kuwa tunaweza kweli kupata hiyo katika mipango yetu pia.

1027
01:11:50,000 --> 01:11:55,000
Hii anapata muhimu wakati tunaanza kuzungumza kuhusu baadhi ya miundo data,

1028
01:11:55,000 --> 01:11:58,000
ambayo ni dhana kwamba sisi ni kwenda kuanzisha baadaye.

1029
01:11:58,000 --> 01:12:09,000
>> Lakini kwa sasa, nini unaweza kujua ni kwamba mimi unaweza kujenga pointer eneo hili, x.

1030
01:12:09,000 --> 01:12:12,000
Kwa mfano, mimi unaweza kujenga variable pointer.

1031
01:12:12,000 --> 01:12:16,000
Tunapozalisha variable pointer sisi kutumia nukuu nyota.

1032
01:12:16,000 --> 01:12:21,000
Katika kesi hiyo, hii anasema mimi nina kwenda kujenga pointer int.

1033
01:12:21,000 --> 01:12:24,000
Ni aina tu kama mtu mwingine yeyote.

1034
01:12:24,000 --> 01:12:27,000
Sisi kuwapa variable kama y,

1035
01:12:27,000 --> 01:12:32,000
na kisha sisi kuweka sawa na anuani, kwa anwani.

1036
01:12:32,000 --> 01:12:38,000
Katika kesi hiyo, tunaweza kuweka y kwa uhakika na x

1037
01:12:38,000 --> 01:12:43,000
kwa kuchukua anuani ya x, ambayo sisi kufanya na ampersand hii,

1038
01:12:43,000 --> 01:12:55,000
na kisha sisi kuweka y kwa uhakika na hilo.

1039
01:12:55,000 --> 01:12:59,000
Nini hii haina ni kimsingi kama tunaangalia RAM wetu

1040
01:12:59,000 --> 01:13:02,000
hii inajenga variable tofauti.

1041
01:13:02,000 --> 01:13:04,000
Ni kwenda kumwita y,

1042
01:13:04,000 --> 01:13:06,000
na wakati huu mstari wa kanuni executes

1043
01:13:06,000 --> 01:13:13,000
ni kweli kwenda kujenga pointer kidogo ambayo sisi kawaida kuteka kama mshale,

1044
01:13:13,000 --> 01:13:15,000
na unaweka y kwa uhakika na x.

1045
01:13:15,000 --> 01:13:17,000
Ndiyo.

1046
01:13:17,000 --> 01:13:19,000
[Mwanafunzi] Kama x ni tayari pointer, ingekuwa wewe tu kufanya

1047
01:13:19,000 --> 01:13:22,000
int * y = x badala ya kuwa ampersand?

1048
01:13:22,000 --> 01:13:24,000
Ndiyo.

1049
01:13:24,000 --> 01:13:27,000
Kama x ni tayari pointer, basi unaweza kuweka kuyatumia 2 sawa kwa kila mmoja,

1050
01:13:27,000 --> 01:13:30,000
katika kesi ambayo y bila uhakika na x,

1051
01:13:30,000 --> 01:13:34,000
lakini ingekuwa kumweka kwa chochote x ni akizungumzia.

1052
01:13:34,000 --> 01:13:37,000
Kwa bahati mbaya, sisi ni nje ya muda.

1053
01:13:37,000 --> 01:13:44,000
>> Nini napenda kusema katika hatua hii, tunaweza kuongea kuhusu offline hii,

1054
01:13:44,000 --> 01:13:49,000
lakini napenda kusema ya kuanza kazi kwenye tatizo hili, # 14.

1055
01:13:49,000 --> 01:13:53,000
Unaweza kuona kuna tayari kidogo kujazwa ndani kwa ajili yenu hapa.

1056
01:13:53,000 --> 01:13:57,000
Unaweza kuona kwamba wakati sisi kutangaza kuyatumia 2, int * x na y *,

1057
01:13:57,000 --> 01:14:01,000
na kumbuka kuwa akizungumzia * ijayo kwa kutofautiana ni jambo ambalo lilifanyika mwaka jana.

1058
01:14:01,000 --> 01:14:05,000
Ni zinageuka kuwa hii ni sawa na kile sisi ni kufanya mwaka huu.

1059
01:14:05,000 --> 01:14:11,000
Haijalishi ambapo unaandika * wakati wewe ni kutangaza pointer.

1060
01:14:11,000 --> 01:14:17,000
Lakini sisi wameandika * ijayo kwa aina

1061
01:14:17,000 --> 01:14:24,000
sababu ambayo inafanya wazi kwamba wewe ni kutangaza variable pointer.

1062
01:14:24,000 --> 01:14:27,000
Unaweza kuona kwamba kutangaza kuyatumia 2 inatupa masanduku 2.

1063
01:14:27,000 --> 01:14:31,000
Hapa wakati sisi kuweka x sawa na malloc

1064
01:14:31,000 --> 01:14:34,000
nini hii ni kusema ni kuweka kando kumbukumbu katika lundo.

1065
01:14:34,000 --> 01:14:41,000
Sanduku Hii kidogo hapa hapa, hii mduara, iko kwenye chungu.

1066
01:14:41,000 --> 01:14:43,000
X ni akizungumzia yake.

1067
01:14:43,000 --> 01:14:46,000
Kumbuka kwamba y bado si akizungumzia chochote.

1068
01:14:46,000 --> 01:14:50,000
Ili kupata kumbukumbu-kuhifadhi namba 42 ndani ya x

1069
01:14:50,000 --> 01:14:55,000
tunataka kutumia nini nukuu?

1070
01:14:55,000 --> 01:14:59,000
[Mwanafunzi] * x = 42.

1071
01:14:59,000 --> 01:15:01,000
Hasa, * x = 42.

1072
01:15:01,000 --> 01:15:06,000
Hiyo ina maana kufuata mshale na kutupa 42 katika huko.

1073
01:15:06,000 --> 01:15:09,000
Hapa ambapo sisi kuweka y na x tuna y akizungumzia x.

1074
01:15:09,000 --> 01:15:13,000
Tena, hii ni kama yale Kevin alisema ambapo sisi kuweka y sawa na x.

1075
01:15:13,000 --> 01:15:15,000
Y si akizungumzia x.

1076
01:15:15,000 --> 01:15:19,000
Badala yake, ni akizungumzia nini x ni akizungumzia pia.

1077
01:15:19,000 --> 01:15:24,000
>> Na kisha hatimaye katika sanduku hii ya mwisho kuna 2 iwezekanavyo mambo ambayo tunaweza kufanya.

1078
01:15:24,000 --> 01:15:28,000
Moja ni tunaweza kusema * x = 13.

1079
01:15:28,000 --> 01:15:33,000
Jambo jingine ni tunaweza kusema-Alex, unajua nini tunaweza kufanya hapa?

1080
01:15:33,000 --> 01:15:37,000
Unaweza kusema * x = 13 au-

1081
01:15:37,000 --> 01:15:41,000
[Mwanafunzi] Unaweza kusema chochote int.

1082
01:15:41,000 --> 01:15:45,000
[Nate H.] Kama hili walikuwa inajulikana kama variable int tunaweza kufanya hivyo.

1083
01:15:45,000 --> 01:15:49,000
Tunaweza pia kusema * y = 13 kwa sababu wao ni wawili akizungumzia nafasi sawa,

1084
01:15:49,000 --> 01:15:51,000
hivyo tunaweza kutumia ama variable ya kufika huko.

1085
01:15:51,000 --> 01:15:56,000
Yeah. >> [Mwanafunzi] gani ni kuangalia kama ikiwa sisi tu kusema x int ni 13?

1086
01:15:56,000 --> 01:16:00,000
Kwamba itakuwa kutangaza variable mpya iitwayo x, ambayo si kazi.

1087
01:16:00,000 --> 01:16:04,000
Tunatarajia kuwa na mgongano kwa sababu sisi alitangaza x kuwa pointer hapa juu.

1088
01:16:04,000 --> 01:16:10,000
[Mwanafunzi] Kama sisi tu alikuwa na kwamba taarifa na yenyewe itakuwa ya namna gani kuangalia kama katika suala la mduara?

1089
01:16:10,000 --> 01:16:14,000
Kama tungekuwa na x = 13 basi tunatarajia kuwa na sanduku, na badala ya kuwa na mshale

1090
01:16:14,000 --> 01:16:16,000
kuja nje ya sanduku tunatarajia kuteka ni kama 13 tu.

1091
01:16:16,000 --> 01:16:19,000
[Mwanafunzi] Katika sanduku. Sawa.

1092
01:16:19,000 --> 01:16:24,000
>> Asante kwa kuangalia, na bahati nzuri juu ya Quiz 0.

1093
01:16:24,000 --> 01:16:28,000
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