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[Powered by Google Translate] [Wiki 4]

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[David J. Malan] [Chuo Kikuu cha Harvard]

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[Hii ni CS50.] [CS50.TV]

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>> Haki zote, hii ni CS50, na hii ni mwanzo wa wiki 4,

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na hii ni moja ya algorithms slowest iwezekanavyo upangaji.

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Ambayo moja ilikuwa ni kwamba sisi wanaangalia tu huko?

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Hiyo ilikuwa Bubble aina, ili kubwa O (n ^ 2) + Jumla,

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na kwa kweli sisi si wale tu katika ulimwengu huu ili wanaonekana kujua

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nini Bubble aina ni wakati wake au kukimbia.

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Hakika, huyu alikuwa mahojiano na Eric Schmidt ya Google

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na seneta wa zamani wa Barack Obama miaka michache tu iliyopita.

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>> Sasa, Seneta, uko hapa katika Google,

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na mimi kama kufikiri ya urais kama mahojiano ya kazi.

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Sasa, ni vigumu kupata kazi kama rais, na mtaenda kupitia rigors sasa.

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Ni pia vigumu kupata kazi saa Google.

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Tuna maswali, na sisi kuuliza maswali wagombea wetu,

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na hii ni moja ya kutoka Larry Schwimmer.

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You guys kufikiri mimi nina kidding? Ni haki hapa.

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Ni njia gani bora zaidi ya kutatua milioni integers 32-bit?

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[Kicheko]

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Naam-

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Samahani. >> Hapana, hapana, hapana, hapana.

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Nadhani aina Bubble itakuwa njia sahihi ya kwenda.

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>> Haya, ambaye alimwambia hii?

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Wiki iliyopita wanakumbuka sisi alichukua kuvunja kutoka code, angalau kwa siku,

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na kuanza kuelekeza nguvu katika mawazo ya baadhi ya ngazi za juu na kutatua tatizo zaidi kwa ujumla

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katika muktadha wa kutafuta na kuchagua,

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na sisi ilianzisha kitu ambacho hatukuwa kofi jina hili katika wiki ya mwisho,

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lakini asymptotic nukuu, O Big, Omega Big,

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na wakati mwingine Big Theta nukuu, na hawa walikuwa tu njia

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ya kuelezea wakati mbio ya algorithms,

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muda kiasi gani inachukua kwa algorithm kukimbia.

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>> Na unaweza kukumbuka kuwa wewe kuongelea wakati mbio katika suala la kawaida

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wa pembejeo, ambayo sisi ujumla kuwaita n, chochote tatizo inaweza kuwa,

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ambapo n ni idadi ya watu katika chumba,

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idadi ya kurasa katika kitabu cha simu, na sisi kuanza kuandika mambo ya nje

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kama O (n ^ 2) au O (n) au O (n logi n),

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na hata wakati math haikuweza kufanya kazi nje hivyo kikamilifu

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na ilikuwa n ² - n / 2 au kitu kama hicho

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tunataka badala tu kutupa baadhi ya maneno ya chini ili,

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na motisha huko ni kwamba sisi kweli unataka

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aina ya njia lengo la kutathmini

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utendaji wa mipango au utendaji wa algorithms

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kwamba, mwisho wa siku hauhusiani, kwa mfano,

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kwa kasi ya leo ya kompyuta yako.

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>> Kwa mfano, kama wewe kutekeleza Bubble aina ya,

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au wewe kutekeleza kuchanganya aina au uteuzi aina ya kompyuta ya leo,

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2 GHz kompyuta, na wewe kukimbia,

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na inachukua baadhi ya idadi ya sekunde, mwaka ujao kuna GHz 3

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au 4 GHz kompyuta, na unaweza kisha kudai kwamba "Wow, algorithm yangu

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sasa ni mara mbili kwa haraka, "wakati katika hali halisi hiyo ni wazi si kesi.

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Ni tu vifaa imenipatia kasi, lakini yako kompyuta

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hana, na hivyo sisi kweli unataka kutupa mbali mambo kama

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kigawe cha 2 au 3 vigawe vya linapokuja kuelezea

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jinsi ya kufunga au jinsi polepole algorithm ni kweli na mtazamo tu

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juu ya n au baadhi ya sababu yake,

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baadhi ya nguvu zake kama katika kesi ya aina kutoka wiki iliyopita.

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Na kukumbuka kwamba kwa msaada wa aina kuunganisha

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tulikuwa na uwezo wa kufanya hivyo bora zaidi kuliko aina Bubble na aina uteuzi

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na hata insertion aina.

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>> Sisi got chini n logi n, na tena,

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kukumbuka kwamba kwa logi n ujumla inahusu kitu ambacho hukua

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zaidi polepole basi n, hivyo n logi n hivi sasa ilikuwa nzuri

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kwa sababu ilikuwa chini ya ² n.

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Lakini kufikia n logi n pamoja na aina kuunganisha

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nini ilikuwa kijidudu msingi wa wazo kwamba tulikuwa na kujiinua

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kwamba sisi pia leveraged nyuma katika wiki 0?

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Jinsi gani sisi kukabiliana na tatizo kuchagua cleverly na aina kuunganisha?

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Nini ilikuwa ufahamu muhimu, labda?

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Mtu yeyote wakati wote.

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Okay, hebu kuchukua hatua nyuma.

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Elezea kuchanganya aina katika maneno yako mwenyewe.

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Jinsi gani kazi?

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Okay, tutaweza mstari nyuma 0 wiki.

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Okay, yeah.

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[Inaudible-mwanafunzi]

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Okay, nzuri, hivyo sisi kugawanywa safu ya idadi katika vipande 2.

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Sisi sorted kila vipande hizo, na kisha sisi ilijiunga nao,

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na tumeona wazo hili kabla ya kuchukua tatizo hilo ni kubwa hii

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na chopping ni juu katika tatizo hilo ni kubwa au hii hii kubwa.

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>> Kumbuka kitabu cha simu mfano.

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Kumbuka algorithm binafsi kuhesabu kutoka wiki iliyopita,

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aina hivyo kuunganisha kilifanyiwa ufupisho na hii pseudocode hapa.

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Wakati wewe ni kupewa vipengele n, kwanza ilikuwa sanity kuangalia.

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Kama n <2 basi si kufanya chochote wakati wote

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kwa sababu kama n <2 kisha n ni wazi 0 au 1,

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na hivyo kama ni aidha 0 au 1 kuna kitu kutatua.

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Wewe ni kosa.

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Orodha yako tayari trivially Iliyopangwa.

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Lakini vinginevyo kama nimepata vipengele 2 au zaidi kwenda mbele na kugawanya yao

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ndani ya 2 halves, kushoto na kulia.

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Aina ya kila halves hizo, na kisha kuunganisha halves Iliyopangwa.

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Lakini tatizo hapa ni kwamba katika mtazamo wa kwanza hii anahisi kama tuko punting.

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Hii ni ufafanuzi katika mviringo kwamba kama nimekuwa aliuliza wewe kuchambua mambo haya n

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na wewe kuniambia "Sawa, faini, tutaweza kuchambua vipengele wale n / 2 na wale n / 2,"

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basi swali yangu ijayo itakuwa ni "Sawa, ni jinsi gani unaweza kutatua n / vipengele 2?"

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>> Lakini kwa sababu ya muundo wa mpango huu,

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kwa sababu kuna kesi hii ya msingi, ili kuzungumza,

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kesi hii maalum kwamba anasema kama ni n <baadhi thamani ya kudumu kama kurudi 2 mara moja.

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Je, si kujibu kwa jibu huo mviringo.

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Utaratibu huu, cyclicity hii hatimaye mwisho.

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Kama mimi kuuliza wewe "Panga elementi hizi n," na kusema, "Sawa, wachambue n / 2,"

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kisha wewe sema, "Sawa, aina hizi n / 4, n / 8, n/16,"

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hatimaye itabidi kugawanya na idadi kubwa ya kutosha

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kwamba itabidi tu 1 kipengele kushoto, ambapo kiwango unaweza kusema,

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"Hapa, hapa ni sorted moja ya kipengele."

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Ndipo uzuri wa algorithm hii hapa ni kwa hupata kutokana na ukweli

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kwamba mara una yote ya orodha hizi kibinafsi Iliyopangwa,

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yote ambayo ni ya kawaida ya 1, ambayo inaonekana kuwa haina maana,

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mara moja kuanza kuunganisha yao na kuunganisha yao

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wewe kujenga hatimaye kama Rob alifanya katika video orodha hatimaye Iliyopangwa.

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>> Lakini wazo hili hadi mbali mbali upangaji.

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Kuna wazo hili iliyoingia katika mpango huu unaojulikana kama recursion,

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wazo ambapo wewe ni mpango,

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na kutatua baadhi ya matatizo hatajali

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au kuweka katika muktadha wa lugha ya programu wewe ni kazi,

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na ili kutatua tatizo, wewe kazi hatajali

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tena na tena na tena, lakini ninyi kazi

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hawawezi kuwaita mwenyewe mara nyingi kubwa.

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Hatimaye una chini nje, ili kuzungumza,

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na kuwa na baadhi ngumu-coded msingi hali ya kuwa anasema

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katika hatua hii kuacha wito mwenyewe ili mchakato mzima

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hatimaye haina ukweli katika kuacha.

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Je, hii kweli maana, kwa recurse?

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>> Hebu angalia, kama tunaweza kufanya rahisi, trivial mfano na, kusema,

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3 watu na mimi hapa juu ya hatua, kama mtu ni starehe.

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1, kuja juu juu, 2 na 3.

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Kama 3 wanataka kuja hapa.

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Kama unataka kusimama haki ya karibu na mimi hapa katika mstari, kudhani kwamba tatizo katika mkono

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ni sana trivially kuhesabu idadi ya watu ambao ni hapa.

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Lakini kusema ukweli, mimi nimechoka ya mifano yote kuhesabu kura.

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Hii ni kwenda kuchukua muda, 1, 2, na dot, dot, dot.

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Ni kwenda kuchukua milele.

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Nisingependa tu punt tatizo hili kabisa na msaada wa-nini jina lako?

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Sara. >> Sara, wote haki.

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Kelly. >> Kelly na?

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>> Willy >> Willy, Sara, Kelly, na Willy..

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Hivi sasa nimekuwa aliuliza swali na mtu

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jinsi watu wengi juu ya hatua hii, na mimi sina wazo.

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Hii ni orodha kweli kwa muda mrefu, na hivyo badala mimi naenda kufanya hila hii.

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Mimi naenda kuuliza mtu karibu na mimi kufanya zaidi ya kazi,

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na mara moja yeye ni kufanyika kufanya zaidi ya kazi

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Mimi naenda kufanya kiasi mdogo wa kazi iwezekanavyo na kuongeza tu 1

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kwa kila jibu lake, hivyo hapa sisi kwenda.

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Nimekuwa aliuliza jinsi watu wengi juu ya hatua.

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Jinsi watu wengi ni juu ya hatua ya kushoto ya wewe?

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kushoto kwangu? >> Sawa, lakini si kudanganya.

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Hiyo ni nzuri, hiyo ni sahihi, lakini kama tunataka kuendelea mantiki hii

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hebu kudhani kuwa wewe vile vile wanataka punt tatizo hili kwa upande wa kushoto wa wewe,

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hivyo badala ya jibu moja kwa moja kwenda mbele na kupita tu mume.

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Oh, jinsi watu wengi ni ya kushoto ya mimi?

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Jinsi watu wengi ni wa kushoto?

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1.

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[Kicheko]

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Sawa, hivyo 0, ili kile sasa Willy amefanya

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ni ve akarudi jibu lako mwelekeo huu akisema 0.

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Sasa, unapaswa kufanya nini >> 1?.

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Okay, hivyo wewe ni 1, hivyo kusema, "Sawa, mimi nina kwenda kuongeza 1

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kwa chochote kuhesabu Willy ilikuwa, "hivyo 1 + 0.

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Wewe ni sasa 1 hivyo jibu lako kwa haki ni sasa-

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1. >> Na mgodi itakuwa 2.

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Nzuri, hivyo wewe ni kuchukua jibu la awali la 1,

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kuongeza kiwango cha chini cha kazi unataka kufanya, ambayo ni 1.

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Sasa una 2, na wewe kisha mkono mimi ambayo thamani?

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3, I mean, sorry, 2.

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Nzuri.

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>> Naam, tulikuwa 0 wa kushoto.

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Kisha sisi alikuwa 1, na kisha sisi kuongeza 2,

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na sasa wewe ni handing alinipa namba 2,

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na hivyo mimi kusema, sawa, 1, 3.

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Kuna hakika 3 watu wamesimama karibu na mimi juu ya hatua hii,

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hivyo tunaweza kuwa wazi jambo hili sana linearly,

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sana katika mtindo wazi, lakini nini sisi kwa kweli kufanya?

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Sisi alichukua tatizo la ukubwa 3 awali.

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Sisi basi wakaiangusha katika tatizo la ukubwa 2,

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basi tatizo ya kawaida ya 1, na kisha hatimaye kesi ya msingi

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alikuwa kweli, oh, hakuna mtu huko,

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ambapo kiwango Willy akarudi ufanisi jibu ngumu-coded michache mara,

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na wa pili alikuwa kisha bubbled up, bubbled up, bubbled up,

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na kisha kwa kuongeza katika 1 hii moja ya ziada

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tumekuwa kutekelezwa hii wazo msingi wa recursion.

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>> Sasa, katika kesi hii ni kweli hakuwa kutatua tatizo

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yoyote kwa ufanisi zaidi kisha tumeona hivi sasa.

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Lakini kufikiri kuhusu algorithms tumefanya juu ya hatua ya hivi sasa.

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Tulikuwa na vipande 8 ya karatasi ubaoni,

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kwenye video wakati Sean mara kutafuta namba 7, na nini alifanya kweli kufanya?

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Naam, hakufanya aina yoyote ya mgawanyiko na kushinda.

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Hakufanya aina yoyote ya recursion.

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Badala yake yeye tu alifanya hivyo algorithm linear.

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Lakini wakati sisi alianzisha wazo la idadi sorted juu ya hatua ya kuishi wiki iliyopita

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kisha sisi alikuwa na haya Instinct ya kwenda katikati,

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ambapo kiwango tulikuwa orodha ndogo ya kawaida 4 au nyingine orodha ya ukubwa 4,

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na kisha sisi alikuwa exact tatizo, hivyo sisi mara kwa mara, mara kwa mara, mara kwa mara.

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Kwa maneno mengine, sisi recursed.

195
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Asante sana kwa kujitolea wetu 3 hapa kwa kuonyesha recursion na sisi.

196
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>> Hebu angalia kama hatuwezi kufanya hii sasa kidogo zaidi halisi,

197
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kutatua tatizo hilo tena tunaweza kufanya pretty urahisi,

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lakini tutaweza kutumia kama jiwe la kuvukia kwa kutekeleza wazo la msingi.

199
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Kama mimi nataka compute summation ya rundo la idadi,

200
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kwa mfano, kama wewe kupita katika namba 3,

201
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Nataka kukupa thamani ya sigma 3,

202
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hivyo Jumla ya 3 + 2 + 1 + 0.

203
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Nataka kupata nyuma jibu 6,

204
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hivyo tutaweza kutekeleza kazi hii sigma, kazi hii summation

205
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tena kuwa, inachukua katika pembejeo, na kisha anarudi summation

206
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ya idadi hiyo njia yote chini 0.

207
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Tunaweza kufanya hili pretty tu, sawa?

208
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Tunaweza kufanya hili kwa baadhi ya aina ya muundo looping,

209
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hivyo basi mimi kwenda mbele na kupata hii ilianza.

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>> Pamoja stdio.h.

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Hebu kupata mwenyewe ndani ya kuu ya kufanya kazi na hapa.

212
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Hebu kuokoa hii kama sigma.c.

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Kisha mimi nina kwenda katika hapa, na mimi nina kwenda kutangaza n int,

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na mimi naenda kufanya yafuatayo wakati mtumiaji hana kushirikiana.

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Wakati mtumiaji kwamba hakunipa idadi chanya

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napenda kwenda mbele na kuwachochea kwa n GetInt =,

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na napenda kuwapa baadhi ya maelekezo kama kwa nini cha kufanya,

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hivyo printf ("Chanya integer tafadhali").

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Tu kitu rahisi kama hii ili kwa wakati sisi hit line 14

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sisi sasa kuwa na integer chanya ikatengeneza katika n.

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>> Sasa hebu kufanya kitu kwa hayo.

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Hebu kwenda mbele na compute summation, hivyo int Jumla = sigma (n).

223
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Sigma ni summation, hivyo mimi nina kuandika tu katika njia fancier.

224
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Tutaweza tu kuiita sigma huko.

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Hiyo ni jumla, na sasa mimi naenda magazeti nje matokeo,

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printf ("Jumla ni% d, \ n", jumla).

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Na basi mimi itabidi kurudi 0 ajili ya hatua nzuri.

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Tumefanya kila kitu kwamba mpango huu inahitaji isipokuwa sehemu ya kuvutia,

229
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ambayo ni ya kweli kutekeleza kazi sigma.

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>> Hebu kwenda chini hapa chini, na napenda kutangaza kazi sigma.

231
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Ni got kuchukua variable kwamba integer ya aina,

232
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na kile data aina mimi nataka kurudi ikatengeneza kutoka sigma?

233
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Int, kwa sababu mimi nataka mechi matarajio yangu juu ya mstari 15.

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Katika hapa napenda kwenda mbele na kutekeleza mpango huu wa

235
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katika njia pretty moja kwa moja.

236
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>> Hebu kwenda mbele na kusema int Jumla = 0,

237
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na sasa mimi nina kwenda kuwa kidogo kwa kitanzi hapa

238
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kwamba kinaendelea kusema kitu kama hiki,

239
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kwa ajili ya (i = 0 int; mimi <= idadi; i + +) Jumla + = i.

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Na kisha mimi naenda kurudi Jumla.

241
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Ningeweza kutekelezwa hii katika idadi yoyote ya njia.

242
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Ningeweza kutumika kitanzi wakati.

243
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Ningeweza kutumia skipped variable Jumla kama kweli alitaka,

244
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lakini katika muda mfupi, sisi tu kazi kwamba kama mimi si goof anatangaza Jumla ni 0.

245
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Kisha iterates kutoka 0 juu ya juu kupitia namba,

246
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na juu ya kila iteration inaongeza kwamba thamani ya sasa kwa jumla na kisha anarudi Jumla.

247
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>> Sasa, kuna optimization kidogo hapa.

248
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Hii pengine ni hatua kupita, lakini na iwe hivyo. Hiyo faini kwa sasa.

249
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Sisi ni angalau kuwa ya uhakika na kwenda 0 njia yote juu juu.

250
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Si ngumu sana na pretty moja kwa moja,

251
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lakini zinageuka kuwa na kazi ya sigma tuna fursa sawa

252
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kama tulivyofanya hapa jukwaani.

253
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Juu ya hatua sisi tu kuhesabiwa watu wangapi walikuwa karibu na mimi,

254
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lakini badala yake kama sisi alitaka kuhesabu idadi 3 + 2 + 1

255
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juu ya chini 0 tunaweza vile vile punt kwa kazi

256
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kwamba mimi itabidi badala kuelezea kuwa kujirudia.

257
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Hapa hebu kufanya sanity haraka kuangalia na kuhakikisha kuwa sikuweza goof.

258
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>> Najua kuna angalau jambo moja katika mpango huu kwamba sikuwa kufanya makosa.

259
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Wakati mimi enter mimi kwenda kupata aina yoyote ya yelling saa yangu?

260
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Je, Mimi naenda kuwa yelled saa kuhusu?

261
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Yeah, I forgot mfano, hivyo mimi nina kutumia kazi kuitwa sigma kwenye mstari 15,

262
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lakini si alitangaza mpaka mstari 22, hivyo mimi bora proactively kwenda hapa

263
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na kutangaza mfano, na mimi itabidi kusema int sigma (int idadi), na hiyo ni yake.

264
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Ni kutekelezwa chini.

265
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>> Au njia nyingine ningeweza kutatua hili,

266
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Mimi nilikuwa hoja kazi huko, ambayo si mbaya,

267
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lakini angalau wakati mipango yako kuanza kupata muda mrefu, kusema ukweli,

268
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Nadhani kuna baadhi ya thamani katika daima kuwa kuu kwa juu

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ili katika msomaji anaweza kufungua faili na kisha mara moja kuona

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nini mpango ni kufanya bila ya kuwa na kutafuta njia hiyo

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kuangalia kwa kazi ambayo kuu.

272
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Hebu kwenda chini kwa terminal dirisha yangu hapa, kujaribu kufanya sigma kufanya sigma,

273
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na mimi Star up hapa pia.

274
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Kinachojitokeza tamko la GetInt kazi ina maana nimepata wamesahau kufanya nini kingine?

275
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[Inaudible-mwanafunzi]

276
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Nzuri, hivyo inaonekana makosa ya kawaida, hivyo hebu kuweka hii hapa,

277
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cs50.h, na sasa hebu kwenda nyuma terminal dirisha yangu.

278
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>> Mimi itabidi wazi screen, na mimi itabidi kufanya rerun sigma.

279
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Inaonekana compiled. Hebu sasa kukimbia sigma.

280
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Mimi itabidi aina katika namba 3, na mimi kupata 6, hivyo si cheki ukali,

281
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lakini angalau ni inaonekana kufanya kazi katika mtazamo wa kwanza, lakini sasa hebu mpasuko ni mbali,

282
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na hebu kweli kujiinua wazo la recursion, tena,

283
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katika muktadha rahisi sana hivyo kwamba katika muda wiki chache '

284
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wakati sisi kuanza kuchunguza miundo data fancier kuliko arrays

285
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tuna chombo mwingine katika toolkit na ambayo kwa

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kuendesha miundo hiyo data kama tutaweza kuona.

287
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Hii ni njia iterative, mbinu kitanzi-msingi.

288
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>> Hebu badala yake sasa kufanya hili.

289
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Hebu badala yake kusema kuwa summation ya idadi

290
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juu ya chini 0 ni kweli kitu sawa kama

291
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idadi + sigma (idadi - 1).

292
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Kwa maneno mengine, kama tu juu ya hatua ya mimi punted kwa kila mmoja wa watu karibu na mimi,

293
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na wao kwa upande naendelea punting mpaka sisi hatimaye bottomed nje katika Willy,

294
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ambaye alikuwa na kurudi jibu ngumu-coded kama 0.

295
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Hapa sasa tuko vile vile punting kwa sigma

296
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kazi sawa kama awali ilikuwa inaitwa, lakini ufahamu muhimu hapa

297
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ni kwamba sisi siyo wito sigma identically.

298
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Sisi siyo kupita katika n.

299
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Sisi ni wazi kupita katika idadi - 1,

300
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hivyo tatizo kidogo kidogo, kidogo kidogo tatizo.

301
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>> Bahati mbaya, hii si kabisa ufumbuzi bado, na kabla ya sisi kurekebisha

302
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kile kinachoweza kuruka nje kama dhahiri katika baadhi ya wewe

303
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napenda kwenda mbele na rerun kufanya.

304
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Inaonekana kukusanya sawa.

305
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Hebu rerun sigma na 6.

306
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Whoops, basi mimi rerun sigma na 6.

307
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Tumeona hii kabla, angalau wakati ajali mwisho pia.

308
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Kwa nini mimi kupata hii cryptic segmentation kosa? Yeah.

309
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[Inaudible-mwanafunzi]

310
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Hakuna kesi ya msingi, na hasa zaidi, nini pengine kilichotokea?

311
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Hii ni dalili ya nini tabia?

312
00:16:58,000 --> 00:17:00,000
Sema ni kidogo nguvu zaidi.

313
00:17:00,000 --> 00:17:02,000
[Inaudible-mwanafunzi]

314
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Ni kitanzi usio ufanisi, na tatizo na matanzi usio

315
00:17:05,000 --> 00:17:08,000
wakati wao kuhusisha recursion katika kesi hii, kazi linalojiita,

316
00:17:08,000 --> 00:17:10,000
nini kinatokea kila wakati wewe piga kazi?

317
00:17:10,000 --> 00:17:13,000
Naam, tafakari jinsi sisi kuweka nje ya kumbukumbu katika kompyuta.

318
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Sisi alisema kuwa kuna hii chunk ya kumbukumbu aitwaye stack kwamba chini,

319
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na kila wakati wewe piga kazi kidogo zaidi ya kumbukumbu anapata kuweka

320
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juu ya hii stack kinachojulikana zenye kwamba kazi ya vigezo ya ndani au vigezo,

321
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hivyo kama sigma wito wito sigma sigma wito sigma

322
00:17:27,000 --> 00:17:29,000
 wito sigma ambapo gani hii mwisho hadithi?

323
00:17:29,000 --> 00:17:31,000
>> Naam, ni hatimaye kuongezeka kiasi jumla ya

324
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ya kumbukumbu kwamba una inapatikana kwa kompyuta yako.

325
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Wewe overrun sehemu kwamba wewe wanatakiwa kukaa ndani,

326
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na wewe kupata hii kosa segmentation, msingi madini,

327
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na nini maana ya msingi zinatupwa ni kwamba mimi sasa wana faili inayoitwa msingi

328
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ambayo ni faili zenye zeros na wale

329
00:17:46,000 --> 00:17:49,000
kwamba kwa kweli katika siku zijazo itakuwa diagnostically muhimu.

330
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Kama siyo dhahiri kwenu ambapo mdudu yako ni

331
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unaweza kweli kufanya kidogo ya uchambuzi wa kisayansi, ili kuzungumza,

332
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kwenye faili hii dampo ya msingi, ambayo, tena, ni tu rundo zima la zeros na wale

333
00:17:58,000 --> 00:18:02,000
kwamba kimsingi inawakilisha hali ya programu yako katika kumbukumbu

334
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sasa ni kugonga kwa njia hii.

335
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>> fix hapa ni kwamba hatuwezi tu upofu kurudi sigma,

336
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idadi + sigma ya tatizo kidogo kidogo.

337
00:18:14,000 --> 00:18:16,000
Tunahitaji kuwa na aina fulani ya kesi ya msingi hapa,

338
00:18:16,000 --> 00:18:19,000
na kile lazima kesi ya msingi pengine kuwa?

339
00:18:19,000 --> 00:18:22,000
[Inaudible-mwanafunzi]

340
00:18:22,000 --> 00:18:25,000
Sawa, hivyo muda mrefu kama idadi ni chanya sisi lazima kweli kurudi huu,

341
00:18:25,000 --> 00:18:29,000
au kuweka njia nyingine, ikiwa ni idadi, kusema, <= kwa 0

342
00:18:29,000 --> 00:18:32,000
unajua nini, mimi itabidi kwenda mbele na kurudi 0,

343
00:18:32,000 --> 00:18:36,000
kiasi kama Willy alivyofanya, na kingine, mimi nina kwenda mbele

344
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na kurudi huu, hivyo si kwamba kiasi mfupi

345
00:18:41,000 --> 00:18:44,000
kuliko toleo iterative kwamba sisi kuchapwa up kwanza kutumia kwa kitanzi,

346
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lakini taarifa kwamba kuna aina hii ya ulimbwende hayo.

347
00:18:48,000 --> 00:18:51,000
Badala ya kurejea baadhi ya idadi na kufanya math hii yote

348
00:18:51,000 --> 00:18:54,000
na kuongeza mambo juu kwa vigezo mitaa

349
00:18:54,000 --> 00:18:57,000
wewe badala kusema "Sawa, kama hii ni super rahisi tatizo,

350
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kama idadi ni <0, basi mimi mara moja kurudi 0. "

351
00:19:01,000 --> 00:19:03,000
>> Sisi siyo kwenda bother kusaidia idadi hasi,

352
00:19:03,000 --> 00:19:05,000
hivyo mimi nina kwenda code ngumu thamani ya 0.

353
00:19:05,000 --> 00:19:08,000
Lakini vinginevyo, kutekeleza wazo hili la summing

354
00:19:08,000 --> 00:19:11,000
yote ya namba hizi pamoja unaweza ufanisi kuchukua bite ndogo

355
00:19:11,000 --> 00:19:14,000
nje ya tatizo, kiasi kama tulivyofanya hapa juu ya hatua,

356
00:19:14,000 --> 00:19:18,000
kisha punt ya mapumziko ya tatizo kwa mtu mwingine,

357
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lakini katika kesi hii mtu mwingine ni wewe mwenyewe.

358
00:19:20,000 --> 00:19:22,000
Ni kazi identically jina.

359
00:19:22,000 --> 00:19:25,000
Kupita tu ni tatizo na ndogo ndogo na ndogo kila wakati,

360
00:19:25,000 --> 00:19:28,000
na hata kama hatuna kabisa rasmi katika mambo code hapa

361
00:19:28,000 --> 00:19:33,000
hii ni nini hasa kinachoendelea katika wiki 0 na kitabu cha simu.

362
00:19:33,000 --> 00:19:36,000
Hii ni nini hasa kinachoendelea katika kipindi cha wiki na Sean

363
00:19:36,000 --> 00:19:39,000
na kwa maandamano yetu ya kutafuta kwa idadi.

364
00:19:39,000 --> 00:19:42,000
Ni kuchukua tatizo na kugawa tena na tena.

365
00:19:42,000 --> 00:19:44,000
>> Kwa maneno mengine, kuna njia ya kutafsiri sasa

366
00:19:44,000 --> 00:19:47,000
hii ulimwengu halisi ya kujenga, hii ngazi ya juu ya kujenga

367
00:19:47,000 --> 00:19:51,000
ya kugawanya na kushinda na kufanya kitu tena na tena

368
00:19:51,000 --> 00:19:56,000
katika kanuni, hivyo hii ni kitu tutaona tena baada ya muda.

369
00:19:56,000 --> 00:20:00,000
Sasa, kama kando, kama wewe ni mpya kwa recursion unapaswa angalau kuelewa sasa

370
00:20:00,000 --> 00:20:02,000
kwa nini hii ni funny.

371
00:20:02,000 --> 00:20:05,000
Mimi nina kwenda kwa google.com,

372
00:20:05,000 --> 00:20:17,000
na mimi nina kwenda kutafuta baadhi ya vidokezo na tricks juu ya recursion, kuingia.

373
00:20:17,000 --> 00:20:21,000
Mwambie mtu karibu na wewe kama walikuwa si kucheka tu sasa.

374
00:20:21,000 --> 00:20:23,000
Ulimaanisha recursion?

375
00:20:23,000 --> 00:20:25,000
Ulimaanisha-ah, kuna sisi kwenda.

376
00:20:25,000 --> 00:20:28,000
Okay, sasa hiyo ni ya mapumziko ya kila mtu.

377
00:20:28,000 --> 00:20:30,000
kidogo Pasaka yai iliyoingia mahali fulani huko katika Google.

378
00:20:30,000 --> 00:20:33,000
Kama kando, moja ya viungo sisi kuweka kwenye tovuti ya kozi

379
00:20:33,000 --> 00:20:36,000
kwa leo ni tu hii gridi ya algorithms mbalimbali kuchagua,

380
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baadhi ya ambayo sisi inaonekana katika wiki ya mwisho, lakini nini ni nzuri kuhusu taswira hii

381
00:20:39,000 --> 00:20:43,000
kama wewe kujaribu wrap akili yako karibu mambo mbalimbali kuhusiana na algorithms

382
00:20:43,000 --> 00:20:46,000
kujua kwamba unaweza kwa urahisi sana sasa kuanza na aina tofauti ya pembejeo.

383
00:20:46,000 --> 00:20:50,000
pembejeo zote kuachwa, pembejeo zaidi sorted, pembejeo random na kadhalika.

384
00:20:50,000 --> 00:20:53,000
Kama wewe kujaribu, tena, kutofautisha mambo haya katika akili yako

385
00:20:53,000 --> 00:20:57,000
kutambua kwamba hii URL kwenye tovuti kozi ya juu ya ukurasa Mihadhara

386
00:20:57,000 --> 00:21:00,000
inaweza kukusaidia sababu kupitia baadhi ya wale.

387
00:21:00,000 --> 00:21:05,000
>> Leo sisi hatimaye kupata kutatua tatizo hili kutoka wakati nyuma,

388
00:21:05,000 --> 00:21:08,000
ambayo ilikuwa kwamba kazi hii byta tu hakuwa na kazi,

389
00:21:08,000 --> 00:21:12,000
na nini ilikuwa tatizo la msingi na byta kazi hii,

390
00:21:12,000 --> 00:21:15,000
Lengo la ambayo ilikuwa, tena, kubadilishana thamani hapa na hapa

391
00:21:15,000 --> 00:21:17,000
vile kwamba hii hutokea?

392
00:21:17,000 --> 00:21:20,000
Hii si kweli kazi. Kwa nini?

393
00:21:20,000 --> 00:21:22,000
Yeah.

394
00:21:22,000 --> 00:21:28,000
[Inaudible-mwanafunzi]

395
00:21:28,000 --> 00:21:31,000
Hasa, maelezo kwa bugginess hii

396
00:21:31,000 --> 00:21:34,000
tu kwa sababu wakati wewe piga kazi katika C

397
00:21:34,000 --> 00:21:38,000
na wale kazi kuchukua hoja, kama na b hapa,

398
00:21:38,000 --> 00:21:42,000
wewe ni kupita katika nakala ya thamani chochote wewe ni kutoa kwa kazi hiyo.

399
00:21:42,000 --> 00:21:46,000
Wewe si kutoa maadili awali wenyewe,

400
00:21:46,000 --> 00:21:49,000
hivyo tuliona hii katika muktadha wa buggyc,

401
00:21:49,000 --> 00:21:52,000
buggy3.c, ambayo inaonekana kitu kidogo kama hii.

402
00:21:52,000 --> 00:21:57,000
>> Kumbuka kwamba tulikuwa x na y initialized kwa 1 na 2, kwa mtiririko huo.

403
00:21:57,000 --> 00:21:59,000
Sisi basi kuchapishwa nini hao.

404
00:21:59,000 --> 00:22:03,000
Mimi kisha alidai kwamba nilikuwa swapping yao kwa wito byta ya x, y.

405
00:22:03,000 --> 00:22:06,000
Lakini tatizo ni kwamba swapping kazi,

406
00:22:06,000 --> 00:22:10,000
lakini tu katika upeo wa kubadilishana kazi yenyewe.

407
00:22:10,000 --> 00:22:13,000
Haraka kama sisi hit mstari 40 wale maadili walibadilishana

408
00:22:13,000 --> 00:22:16,000
walikuwa kutupwa mbali, na hivyo hakuna kitu

409
00:22:16,000 --> 00:22:21,000
katika kazi ya awali kuu ilikuwa kweli iliyopita wakati wote,

410
00:22:21,000 --> 00:22:26,000
hivyo kama unafikiri nyuma basi kama yale hii inaonekana kama katika suala la kumbukumbu yetu

411
00:22:26,000 --> 00:22:29,000
kama hii upande wa mkono wa kushoto wa bodi inawakilisha-

412
00:22:29,000 --> 00:22:33,000
na mimi itabidi kufanya bora wangu kwa kila mtu kuona hii-kama hii upande wa mkono wa kushoto wa bodi

413
00:22:33,000 --> 00:22:37,000
inawakilisha, kusema, RAM yako, na stack anaenda kukua kwenye up njia hii,

414
00:22:37,000 --> 00:22:43,000
na sisi wito kazi kama kuu, na kuu ina vigezo 2 mitaa, x na y,

415
00:22:43,000 --> 00:22:48,000
hebu kuelezea wale kama x hapa, na hebu kueleza haya kama y hapa,

416
00:22:48,000 --> 00:22:55,000
na tulenge katika maadili 1 na 2, hivyo hii hapa ni kuu,

417
00:22:55,000 --> 00:22:58,000
na wakati kuu wito kazi byta mfumo wa uendeshaji

418
00:22:58,000 --> 00:23:02,000
anatoa kazi byta rundo yake mwenyewe ya kumbukumbu juu ya stack,

419
00:23:02,000 --> 00:23:04,000
sura yake mwenyewe katika stack, hivyo kusema.

420
00:23:04,000 --> 00:23:08,000
Ni pia inatenga bits 32 kwa ints haya.

421
00:23:08,000 --> 00:23:11,000
Hufanyika kwa kuwaita na b, lakini hiyo ni kabisa holela.

422
00:23:11,000 --> 00:23:13,000
Inawezekana niliyowaitia chochote anataka, lakini kile kinachotokea wakati kuu

423
00:23:13,000 --> 00:23:19,000
wito byta ni inachukua hii 1, unaweka nakala huko, unaweka nakala huko.

424
00:23:19,000 --> 00:23:23,000
>> Kuna 1 nyingine za mitaa kutofautiana katika byta, ingawa, imeitaja >> TMP?.

425
00:23:23,000 --> 00:23:27,000
TMP, hivyo basi mimi kutoa mwenyewe bits nyingine 32 hapa,

426
00:23:27,000 --> 00:23:29,000
na kwa nini mimi kufanya katika kazi hii?

427
00:23:29,000 --> 00:23:34,000
Mimi alisema TMP int anapata, hivyo ina 1, hivyo sikuwa hii wakati sisi mwisho alicheza na mfano huu.

428
00:23:34,000 --> 00:23:39,000
Kisha b anapata, hivyo b ni 2, hivyo sasa hii inakuwa 2,

429
00:23:39,000 --> 00:23:42,000
na sasa anapata b temp, hivyo temp ni 1,

430
00:23:42,000 --> 00:23:44,000
hivyo sasa b inakuwa hii.

431
00:23:44,000 --> 00:23:46,000
Hiyo ni kubwa. Ni kazi.

432
00:23:46,000 --> 00:23:49,000
Lakini basi kwa haraka kama anarudi kazi

433
00:23:49,000 --> 00:23:52,000
kumbukumbu byta wa ufanisi kutoweka ili iweze kutumika tena

434
00:23:52,000 --> 00:23:58,000
kwa kazi nyingine katika siku zijazo, na ni wazi kabisa kuu unchanged.

435
00:23:58,000 --> 00:24:00,000
Tunahitaji njia ya kimsingi ya kutatua tatizo hili,

436
00:24:00,000 --> 00:24:03,000
na leo hatimaye tutaweza kuwa na njia ya kufanya hili ambapo

437
00:24:03,000 --> 00:24:06,000
tunaweza kuanzisha kitu kinachoitwa pointer.

438
00:24:06,000 --> 00:24:09,000
Ni zinageuka kuwa tunaweza kutatua tatizo hili

439
00:24:09,000 --> 00:24:12,000
si kwa kupita katika nakala za x na y

440
00:24:12,000 --> 00:24:18,000
lakini badala yake kwa kupita katika kile, unafikiri, kwa kazi byta?

441
00:24:18,000 --> 00:24:20,000
Yeah, nini kuhusu anuani?

442
00:24:20,000 --> 00:24:22,000
Sisi si kweli aliyesema kuhusu anwani kwa undani sana,

443
00:24:22,000 --> 00:24:25,000
lakini kama ubao huu inawakilisha kumbukumbu ya kompyuta yangu

444
00:24:25,000 --> 00:24:28,000
tunaweza kuanza shaka hesabu ka katika RAM yangu

445
00:24:28,000 --> 00:24:31,000
na kusema hii ni Byte # 1, hii ni Byte # 2, Byte # 3,

446
00:24:31,000 --> 00:24:35,000
Byte # 4, Byte # ... bilioni 2 kama nina 2 gigabytes ya RAM,

447
00:24:35,000 --> 00:24:38,000
hivyo tunaweza shaka kuja na mpango wa baadhi holela hesabu

448
00:24:38,000 --> 00:24:41,000
kwa ka wote binafsi katika kumbukumbu ya kompyuta yangu.

449
00:24:41,000 --> 00:24:43,000
>> Nini kama badala wakati mimi kuwaita byta

450
00:24:43,000 --> 00:24:47,000
badala ya kupita katika nakala za x na y

451
00:24:47,000 --> 00:24:51,000
nini si mimi badala kupita katika anuani ya x hapa,

452
00:24:51,000 --> 00:24:55,000
anuani ya y hapa, kimsingi anwani ya posta

453
00:24:55,000 --> 00:24:59,000
ya x na y kwa sababu kisha wabadilishane, kama yeye habari

454
00:24:59,000 --> 00:25:01,000
ya anuani katika kumbukumbu ya x na y,

455
00:25:01,000 --> 00:25:04,000
kisha wabadilishane, kama sisi mafunzo yake kidogo,

456
00:25:04,000 --> 00:25:07,000
yeye inaweza uwezekano kuendesha gari kwa anuani ya kwamba, ili kuzungumza,

457
00:25:07,000 --> 00:25:11,000
x, na mabadiliko ya idadi ya huko, basi gari na anuani ya y,

458
00:25:11,000 --> 00:25:16,000
mabadiliko ya idadi ya huko, hata wakati si kweli kupata nakala ya maadili hayo mwenyewe,

459
00:25:16,000 --> 00:25:19,000
hivyo hata kama kuongelea hili kuwa kumbukumbu kuu ya

460
00:25:19,000 --> 00:25:23,000
na kumbukumbu hii byta kama kuwa wa nguvu na sehemu ya hatari ya C

461
00:25:23,000 --> 00:25:28,000
ni kwamba kazi yoyote anaweza kugusa kumbukumbu popote katika kompyuta,

462
00:25:28,000 --> 00:25:32,000
na hii ni nguvu katika kuwa unaweza kufanya mambo sana dhana na programu za kompyuta katika C.

463
00:25:32,000 --> 00:25:36,000
Hii ni hatari kwa sababu unaweza pia screw up kwa urahisi sana.

464
00:25:36,000 --> 00:25:39,000
Kwa kweli, moja ya njia ya kawaida kwa mipango ya siku hizi kutumiwa

465
00:25:39,000 --> 00:25:42,000
bado ni kwa ajili ya programu kutotambua

466
00:25:42,000 --> 00:25:45,000
kwamba yeye au yeye ni kuruhusu data

467
00:25:45,000 --> 00:25:49,000
kwa kuwa imeandikwa katika mahali katika kumbukumbu kuwa mara si nia.

468
00:25:49,000 --> 00:25:51,000
>> Kwa mfano, yeye au yeye anatangaza safu ya kawaida 10

469
00:25:51,000 --> 00:25:56,000
lakini kisha ajali inajaribu kuweka ka 11 ndani ya kwamba safu ya kumbukumbu,

470
00:25:56,000 --> 00:25:59,000
na kuanza kugusa sehemu ya kumbukumbu ya kwamba ni halali tena.

471
00:25:59,000 --> 00:26:02,000
Tu contextual hili, baadhi ya unaweza kujua kwamba

472
00:26:02,000 --> 00:26:06,000
programu mara nyingi prompts kwa idadi Serial au funguo usajili,

473
00:26:06,000 --> 00:26:08,000
Photoshop na Neno na mipango kama hii.

474
00:26:08,000 --> 00:26:12,000
Zipo nyufa, kama baadhi ya wewe kujua, online ambapo unaweza kuendesha programu kidogo,

475
00:26:12,000 --> 00:26:14,000
na voilà, hakuna ombi zaidi kwa idadi Serial.

476
00:26:14,000 --> 00:26:16,000
Je hiyo kazi?

477
00:26:16,000 --> 00:26:21,000
Katika kesi nyingi mambo haya ni tu kutafuta katika kompyuta

478
00:26:21,000 --> 00:26:24,000
Nakala ya makundi katika zeros ya kompyuta halisi na wale

479
00:26:24,000 --> 00:26:28,000
ambapo ni kwamba kazi ambapo idadi Serial ni ombi,

480
00:26:28,000 --> 00:26:31,000
na wewe overwrite kwamba nafasi, au wakati wa mpango ni mbio

481
00:26:31,000 --> 00:26:33,000
unaweza kufikiri ambapo muhimu ni kweli kuhifadhiwa

482
00:26:33,000 --> 00:26:37,000
kutumia kitu kinachoitwa kiweua na unaweza ufa programu kwa njia hiyo.

483
00:26:37,000 --> 00:26:40,000
Hii si kusema kwamba hii ni lengo letu kwa michache ijayo siku,

484
00:26:40,000 --> 00:26:42,000
lakini ina sana ramifications ulimwengu halisi.

485
00:26:42,000 --> 00:26:45,000
Hiyo moja kinachotokea kwa kuhusisha wizi wa programu,

486
00:26:45,000 --> 00:26:47,000
lakini pia kuna maelewano ya mashine nzima.

487
00:26:47,000 --> 00:26:50,000
>> Kwa kweli, wakati tovuti siku hizi ni kunyonywa

488
00:26:50,000 --> 00:26:53,000
na kuathirika na data ni kuvuja na nywila kuibiwa

489
00:26:53,000 --> 00:26:58,000
hii mara nyingi sana inahusiana na usimamizi mbaya wa kumbukumbu ya mtu,

490
00:26:58,000 --> 00:27:01,000
au, katika kesi ya database, kushindwa wanatarajia

491
00:27:01,000 --> 00:27:03,000
adversarial pembejeo, hivyo zaidi juu ya kwamba katika wiki ijayo,

492
00:27:03,000 --> 00:27:07,000
lakini kwa sasa tu sneak preview ya aina ya uharibifu kwamba unaweza kufanya

493
00:27:07,000 --> 00:27:11,000
na si kabisa kuelewa jinsi mambo kazi chini ya Hood.

494
00:27:11,000 --> 00:27:14,000
Hebu kwenda juu kuelewa kwa nini hii ni kuvunjwa

495
00:27:14,000 --> 00:27:17,000
na chombo kwamba litakuwa zaidi na muhimu zaidi

496
00:27:17,000 --> 00:27:19,000
kama mipango yetu kupata ngumu zaidi.

497
00:27:19,000 --> 00:27:21,000
Hivi sasa wakati umeshapata mdudu katika mpango wako

498
00:27:21,000 --> 00:27:23,000
jinsi ya kuwa na wewe zimetimia debugging yake?

499
00:27:23,000 --> 00:27:25,000
Nini mbinu yako imekuwa hivi sasa, kama kufundishwa na TF yako

500
00:27:25,000 --> 00:27:27,000
au tu binafsi kufundishwa?

501
00:27:27,000 --> 00:27:29,000
[Mwanafunzi] Printf.

502
00:27:29,000 --> 00:27:31,000
Printf, hivyo printf ina pengine imekuwa rafiki yako katika kwamba kama unataka kuona

503
00:27:31,000 --> 00:27:33,000
nini kinaendelea ndani ya mpango wako

504
00:27:33,000 --> 00:27:36,000
wewe tu kuweka printf hapa, printf hapa, printf hapa.

505
00:27:36,000 --> 00:27:38,000
Kisha wewe kukimbia, na kupata rundo zima ya mambo ya screen

506
00:27:38,000 --> 00:27:43,000
kwamba unaweza kutumia kisha kuthibitisha kile ni kweli kwenda vibaya katika programu yako.

507
00:27:43,000 --> 00:27:45,000
>> Printf huelekea kuwa kitu chenye nguvu sana,

508
00:27:45,000 --> 00:27:47,000
lakini ni mchakato sana mwongozo.

509
00:27:47,000 --> 00:27:49,000
Una kuweka printf hapa, printf hapa,

510
00:27:49,000 --> 00:27:51,000
na kama wewe kuweka ndani ya kitanzi unaweza kupata mistari 100

511
00:27:51,000 --> 00:27:53,000
ya pato kwamba wewe kisha kuwa na kuchuja.

512
00:27:53,000 --> 00:27:58,000
Ni si sana user-kirafiki au maingiliano utaratibu kwa ajili ya programu debugging,

513
00:27:58,000 --> 00:28:00,000
bali nashiriki kuna njia mbadala.

514
00:28:00,000 --> 00:28:03,000
Kuna programu, kwa mfano, aitwaye GDB, Debugger GNU,

515
00:28:03,000 --> 00:28:06,000
ambayo ni arcane kidogo katika jinsi gani matumizi yake.

516
00:28:06,000 --> 00:28:08,000
Ni ngumu kidogo, lakini kusema ukweli,

517
00:28:08,000 --> 00:28:11,000
hii ni moja ya mambo hayo ambapo kama wewe kuweka katika wiki hii na ijayo

518
00:28:11,000 --> 00:28:14,000
saa za ziada kwa kuelewa kitu kama GDB

519
00:28:14,000 --> 00:28:18,000
itakuwa ila wewe makumi pengine ya masaa katika muda mrefu,

520
00:28:18,000 --> 00:28:21,000
hivyo pamoja na kwamba, nikupe teaser wa jinsi jambo hili kazi.

521
00:28:21,000 --> 00:28:23,000
>> Mimi niko katika terminal dirisha yangu.

522
00:28:23,000 --> 00:28:26,000
Hebu kwenda mbele na kukusanya mpango huu, buggy3.

523
00:28:26,000 --> 00:28:28,000
Ni tayari hadi sasa.

524
00:28:28,000 --> 00:28:31,000
Hebu kukimbia tu kama sisi alifanya nyuma wakati, na kwa kweli, ni kuvunjwa.

525
00:28:31,000 --> 00:28:34,000
Lakini kwa nini hii? Labda mimi Star up kazi byta.

526
00:28:34,000 --> 00:28:37,000
Labda ni na b. Mimi si kabisa kusonga yao kuzunguka usahihi.

527
00:28:37,000 --> 00:28:39,000
Hebu kwenda mbele na kufanya hili.

528
00:28:39,000 --> 00:28:43,000
Badala ya kukimbia tu buggy3 basi mimi badala kukimbia hii GDB mpango,

529
00:28:43,000 --> 00:28:48,000
na mimi naenda kuwaambia kwa kukimbia buggy3,

530
00:28:48,000 --> 00:28:52,000
na mimi naenda kwa pamoja mstari amri hoja,-tui,

531
00:28:52,000 --> 00:28:55,000
na tutaweza kuweka hii katika matatizo ya baadaye katika spec kuwakumbusha.

532
00:28:55,000 --> 00:28:57,000
Na sasa hii interface nyeusi na nyeupe popped up tena kuwa,

533
00:28:57,000 --> 00:28:59,000
ni kidogo mno kwa sababu kwanza kuna haya yote

534
00:28:59,000 --> 00:29:02,000
udhamini habari hapa chini, lakini angalau kuna kitu familiar.

535
00:29:02,000 --> 00:29:04,000
Katika juu ya dirisha ni code yangu halisi,

536
00:29:04,000 --> 00:29:08,000
na kama mimi kitabu juu hapa basi mimi kitabu kwa sana juu ya faili yangu,

537
00:29:08,000 --> 00:29:11,000
na kwa kweli, kuna buggy3.c, na ilani chini ya dirisha hili

538
00:29:11,000 --> 00:29:13,000
Nina haraka GDB.

539
00:29:13,000 --> 00:29:16,000
>> Hii si sawa kama kawaida yangu John Harvard haraka.

540
00:29:16,000 --> 00:29:19,000
Hii ni haraka ambayo inaenda naomba kudhibiti GDB.

541
00:29:19,000 --> 00:29:21,000
GDB ni debugger.

542
00:29:21,000 --> 00:29:24,000
debugger ni programu ambayo inakuwezesha kutembea kwa njia ya

543
00:29:24,000 --> 00:29:27,000
utekelezaji wa mpango wako mstari kwa mstari kwa mstari,

544
00:29:27,000 --> 00:29:30,000
njiani kufanya kitu chochote unataka mpango,

545
00:29:30,000 --> 00:29:33,000
hata wito kazi, au kuangalia, muhimu zaidi,

546
00:29:33,000 --> 00:29:35,000
katika maadili mbalimbali variable ya.

547
00:29:35,000 --> 00:29:37,000
Hebu kwenda mbele na kufanya hili.

548
00:29:37,000 --> 00:29:40,000
Mimi nina kwenda mbele na aina katika kukimbia katika haraka ya GDB,

549
00:29:40,000 --> 00:29:43,000
hivyo ilani chini kushoto ya screen nimekuwa typed kukimbia,

550
00:29:43,000 --> 00:29:45,000
na nimekuwa enter, na ni nini kwamba kufanya?

551
00:29:45,000 --> 00:29:50,000
Ni literally mbio mpango wangu, lakini sikuweza kwa kweli kuona mengi kwenda juu hapa

552
00:29:50,000 --> 00:29:55,000
kwa sababu mimi si kweli aliiambia debugger

553
00:29:55,000 --> 00:29:57,000
pause wakati fulani katika muda.

554
00:29:57,000 --> 00:29:59,000
Kuandika tu kukimbia anaendesha mpango.

555
00:29:59,000 --> 00:30:01,000
Mimi si kweli kuona chochote. Siwezi kuendesha hiyo.

556
00:30:01,000 --> 00:30:03,000
>> Badala yake basi mimi kufanya hili.

557
00:30:03,000 --> 00:30:08,000
Wakati huu wa haraka GDB basi mimi badala aina mapumziko, kuingia.

558
00:30:08,000 --> 00:30:10,000
Hiyo si kile mimi maana ya aina.

559
00:30:10,000 --> 00:30:13,000
Hebu badala aina mapumziko kuu.

560
00:30:13,000 --> 00:30:15,000
Kwa maneno mengine, nataka kuweka kitu kinachoitwa breakpoint,

561
00:30:15,000 --> 00:30:18,000
ambayo ni aptly aitwaye sababu itakuwa kuvunja au pause

562
00:30:18,000 --> 00:30:21,000
utekelezaji wa mpango yako katika mahali fulani.

563
00:30:21,000 --> 00:30:23,000
Kuu ni jina ya kazi yangu.

564
00:30:23,000 --> 00:30:25,000
Ona kwamba GDB ni pretty smart.

565
00:30:25,000 --> 00:30:28,000
Ni figured kwamba kinachotokea kuu kuanza takribani katika mstari 18

566
00:30:28,000 --> 00:30:32,000
ya buggy3.c, na kisha taarifa hapa juu kushoto

567
00:30:32,000 --> 00:30:34,000
b + ni haki ya karibu na mstari 18.

568
00:30:34,000 --> 00:30:38,000
Hiyo mimi nakukumbusha kuwa nimekuwekea breakpoint katika mstari wa 18.

569
00:30:38,000 --> 00:30:42,000
Wakati huu ambapo ninapoandika kukimbia, mimi naenda kuendesha programu yangu

570
00:30:42,000 --> 00:30:45,000
hadi hits kwamba breakpoint,

571
00:30:45,000 --> 00:30:48,000
hivyo mpango mapenzi pause kwa ajili yangu katika mstari wa 18.

572
00:30:48,000 --> 00:30:50,000
Hapa sisi kwenda, kukimbia.

573
00:30:50,000 --> 00:30:53,000
Hakuna inaonekana kuwa kilichotokea, lakini taarifa chini kushoto

574
00:30:53,000 --> 00:30:58,000
kuanza programu, buggy3, breakpoint 1 katika kuu katika buggy3.c line 18.

575
00:30:58,000 --> 00:31:00,000
Naweza kufanya nini sasa?

576
00:31:00,000 --> 00:31:03,000
>> Taarifa mimi unaweza kuanza kuandika mambo kama magazeti,

577
00:31:03,000 --> 00:31:08,000
si printf, magazeti x, na sasa hiyo ni ya ajabu.

578
00:31:08,000 --> 00:31:11,000
$ 1 ni udadisi, kama tutaweza kuona

579
00:31:11,000 --> 00:31:14,000
kila wakati magazeti kitu wewe kupata mwezi $ thamani.

580
00:31:14,000 --> 00:31:18,000
Hiyo ni ili uweze kurejea katika maadili uliopita tu katika kesi,

581
00:31:18,000 --> 00:31:21,000
lakini kwa sasa nini magazeti ananiambia ni kwamba thamani ya x katika hatua hii ya hadithi

582
00:31:21,000 --> 00:31:26,000
inaonekana 134,514,032.

583
00:31:26,000 --> 00:31:29,000
Nini? Wapi kwamba hata kuja kutoka?

584
00:31:29,000 --> 00:31:31,000
[Inaudible-mwanafunzi]

585
00:31:31,000 --> 00:31:34,000
Hakika, huu ni nini Tutamwita thamani ya takataka, na tumekuwa si aliyesema kuhusu hili bado,

586
00:31:34,000 --> 00:31:37,000
lakini sababu ya kwamba wewe initialize vigezo

587
00:31:37,000 --> 00:31:40,000
ni wazi ili wapate kuwa baadhi ya thamani ya kwamba unataka wao kuwa.

588
00:31:40,000 --> 00:31:44,000
Lakini catch ni kukumbuka kuwa unaweza kutangaza vigezo

589
00:31:44,000 --> 00:31:46,000
kama nilivyofanya wakati iliyopita katika mfano wangu sigma

590
00:31:46,000 --> 00:31:48,000
bila ya kweli kuwapa thamani.

591
00:31:48,000 --> 00:31:50,000
Kumbuka nilivyopatenda juu hapa nchini sigma.

592
00:31:50,000 --> 00:31:52,000
Mimi alitangaza n, lakini kile thamani gani mimi kuwapa?

593
00:31:52,000 --> 00:31:56,000
Hakuna, kwa sababu nilijua kwamba katika mistari michache ijayo

594
00:31:56,000 --> 00:31:59,000
GetInt ingekuwa ya utunzaji wa tatizo la kuweka thamani ndani ya n.

595
00:31:59,000 --> 00:32:02,000
>> Lakini katika hatua hii kwa hadithi ya mstari 11

596
00:32:02,000 --> 00:32:05,000
na mstari wa 12 na 13 na line line 14

597
00:32:05,000 --> 00:32:08,000
katika wale mistari kadhaa ni nini thamani ya n?

598
00:32:08,000 --> 00:32:10,000
Katika C wewe tu hawajui.

599
00:32:10,000 --> 00:32:14,000
Ni kwa ujumla baadhi ya thamani ya takataka, baadhi idadi kabisa random

600
00:32:14,000 --> 00:32:17,000
wa kushoto juu ya kimsingi na kazi baadhi ya awali

601
00:32:17,000 --> 00:32:21,000
baada ya kukimbia, hivyo kama mpango wako anaendesha

602
00:32:21,000 --> 00:32:24,000
kukumbuka kuwa kazi anapata kazi, kazi, kazi.

603
00:32:24,000 --> 00:32:27,000
Muafaka haya yote kupata kuweka kwenye kumbukumbu, na kisha wale kurudi kazi,

604
00:32:27,000 --> 00:32:31,000
na kama tu mimi alipendekeza na kifutio kumbukumbu yao ni hatimaye kutumika tena.

605
00:32:31,000 --> 00:32:37,000
Naam, ni tu hivyo hutokea kwamba hii x variable katika mpango huu

606
00:32:37,000 --> 00:32:41,000
inaonekana kuwa zilizomo baadhi thamani takataka kama 134514032

607
00:32:41,000 --> 00:32:44,000
kutoka kwa baadhi kazi ya awali, si moja kwamba mimi aliandika.

608
00:32:44,000 --> 00:32:47,000
Ni inaweza kuwa kitu ambacho huja kwa ufanisi na mfumo wa uendeshaji,

609
00:32:47,000 --> 00:32:49,000
baadhi ya kazi chini ya Hood.

610
00:32:49,000 --> 00:32:52,000
>> Okay, hiyo ni nzuri, lakini hebu sasa mapema ili line ijayo.

611
00:32:52,000 --> 00:32:55,000
Kama mimi aina "ijayo" katika GDB wangu wa haraka na mimi enter,

612
00:32:55,000 --> 00:32:58,000
taarifa kuwa katika kuzungumzia hatua chini ya mstari 19,

613
00:32:58,000 --> 00:33:01,000
lakini Kidokezo kimantiki ni kwamba mstari 18

614
00:33:01,000 --> 00:33:06,000
sasa kumaliza utekelezaji, hivyo kama mimi tena aina "magazeti x"

615
00:33:06,000 --> 00:33:10,000
Mimi lazima sasa angalia 1, na kwa kweli, mimi kufanya.

616
00:33:10,000 --> 00:33:14,000
Tena, stuff $ ni njia ya GDB kuwakumbusha

617
00:33:14,000 --> 00:33:17,000
nini historia ya prints ni kwamba umefanya kosa.

618
00:33:17,000 --> 00:33:21,000
Sasa basi mimi kwenda mbele na magazeti nje y, na kwa hakika, y ni baadhi ya thamani kama mambo vizuri,

619
00:33:21,000 --> 00:33:24,000
lakini hakuna mpango mkubwa kwa sababu katika mstari 19 tuko kuhusu hawawajui ni

620
00:33:24,000 --> 00:33:27,000
thamani 2, hivyo basi mimi andika "ijayo" tena.

621
00:33:27,000 --> 00:33:29,000
Na sasa tuko kwenye mstari printf.

622
00:33:29,000 --> 00:33:31,000
Hebu kufanya x magazeti.

623
00:33:31,000 --> 00:33:34,000
Hebu kufanya magazeti y. Kusema ukweli, mimi nina kupata uchovu kidogo ya uchapishaji huu.

624
00:33:34,000 --> 00:33:38,000
Hebu badala aina "display x" na "kuonyesha y,"

625
00:33:38,000 --> 00:33:41,000
na sasa wakati kila ninapoandika amri katika siku zijazo

626
00:33:41,000 --> 00:33:45,000
Nami kukumbushwa nini x na y, nini x na y, nini x na y.

627
00:33:45,000 --> 00:33:48,000
>> Naweza pia, kama kando, aina katika "wenyeji info."

628
00:33:48,000 --> 00:33:50,000
Info ni amri maalum.

629
00:33:50,000 --> 00:33:52,000
Wenyeji maana yake inaonyesha mimi vigezo mitaa.

630
00:33:52,000 --> 00:33:55,000
Tu katika kesi mimi kusahau au huyu ni mwenda wazimu, ngumu kazi

631
00:33:55,000 --> 00:33:57,000
kwamba mimi au mtu mwingine aliandika maelezo wenyeji atakuambia

632
00:33:57,000 --> 00:34:00,000
kile ni vigezo mitaa yote ndani ya kazi hii mitaa

633
00:34:00,000 --> 00:34:03,000
kwamba unaweza huduma ya juu kama unataka poke kote.

634
00:34:03,000 --> 00:34:07,000
Sasa, printf ni kuhusu kutekeleza, hivyo basi mimi kwenda mbele na aina tu "ujao."

635
00:34:07,000 --> 00:34:10,000
Kwa sababu tuko katika mazingira haya sisi siyo kweli kuona ni

636
00:34:10,000 --> 00:34:14,000
nitafanya hapa chini, lakini taarifa ni kupata kidogo mangled hapa.

637
00:34:14,000 --> 00:34:17,000
Lakini taarifa ni kuu screen pale,

638
00:34:17,000 --> 00:34:21,000
hivyo si mpango kamili hapa, lakini hiyo ni sawa kwa sababu siwezi daima poke kuzunguka

639
00:34:21,000 --> 00:34:23,000
kutumia magazeti kama nataka.

640
00:34:23,000 --> 00:34:26,000
>> Hebu aina ya pili, na sasa hapa ni sehemu ya kuvutia.

641
00:34:26,000 --> 00:34:29,000
Katika hatua hii ya hadithi y ni 2, na x ni 1,

642
00:34:29,000 --> 00:34:32,000
kama unahitajika hapa, na tena,

643
00:34:32,000 --> 00:34:35,000
sababu hii ni moja kwa moja kuonyesha sasa ni kwa sababu mimi kutumika amri

644
00:34:35,000 --> 00:34:40,000
kuonyesha x na y kuonyesha, hivyo wakati ninapoandika ijayo

645
00:34:40,000 --> 00:34:43,000
katika nadharia x na y wanapaswa kuwa swapped.

646
00:34:43,000 --> 00:34:45,000
Sasa, sisi tayari kujua kwamba si kwenda kuwa kesi,

647
00:34:45,000 --> 00:34:49,000
lakini tutaweza kuona katika wakati gani tunaweza kupiga mbizi kwa kina takwimu kwa nini hiyo ni kweli.

648
00:34:49,000 --> 00:34:54,000
Next, na kwa bahati mbaya, bado ni y 2 x na bado ni 1, na naweza kuthibitisha kama mengi.

649
00:34:54,000 --> 00:34:56,000
Print x, y magazeti.

650
00:34:56,000 --> 00:34:59,000
Hakika, hakuna swapping ina hasa kilichotokea, hivyo hebu kuanza hii zaidi.

651
00:34:59,000 --> 00:35:01,000
Wazi byta ni kuvunjwa.

652
00:35:01,000 --> 00:35:04,000
Hebu badala aina "kukimbia" tena.

653
00:35:04,000 --> 00:35:07,000
Hebu kusema ndiyo, nataka kuanzisha upya kuanzia mwanzo, kuingia.

654
00:35:07,000 --> 00:35:09,000
>> Sasa mimi nina nyuma hadi mstari 18.

655
00:35:09,000 --> 00:35:11,000
Sasa taarifa x na y ni takataka maadili tena.

656
00:35:11,000 --> 00:35:15,000
Next, pili, pili, pili.

657
00:35:15,000 --> 00:35:17,000
Kama mimi kupata kuchoka naweza pia aina tu n kwa ajili ya pili.

658
00:35:17,000 --> 00:35:21,000
Unaweza abbreviate kwa mlolongo mfupi iwezekanavyo ya wahusika.

659
00:35:21,000 --> 00:35:23,000
Swap sasa kuvunjwa.

660
00:35:23,000 --> 00:35:25,000
Hebu tuzame katika, hivyo badala ya kuandika ijayo,

661
00:35:25,000 --> 00:35:30,000
sasa mimi naenda aina hatua hivyo kwamba mimi nina wanazidi ndani ya kazi hii

662
00:35:30,000 --> 00:35:33,000
ili niweze kutembea kwa njia yake, hivyo mimi hit hatua na kisha kuingia.

663
00:35:33,000 --> 00:35:37,000
Ona kwamba anaruka mwangaza chini ya chini katika mpango wangu mstari 36.

664
00:35:37,000 --> 00:35:39,000
Sasa nini ni vigezo mitaa?

665
00:35:39,000 --> 00:35:41,000
Info wazawa.

666
00:35:41,000 --> 00:35:43,000
Hakuna bado tu kwa sababu tumekuwa si Gotten kwa kuwa mstari,

667
00:35:43,000 --> 00:35:47,000
hivyo hebu kwenda mbele na kusema "ujao."

668
00:35:47,000 --> 00:35:50,000
Sasa sisi tunaonekana kuwa na TMP, magazeti TMP.

669
00:35:50,000 --> 00:35:52,000
Takataka thamani, haki? Nadhani hivyo.

670
00:35:52,000 --> 00:35:55,000
Vipi kuhusu magazeti, magazeti b, 1 na 2?

671
00:35:55,000 --> 00:35:58,000
Katika wakati huu, haraka kama mimi aina ya pili

672
00:35:58,000 --> 00:36:02,000
TMP ni kwenda kuchukua juu ya thamani ya 1, hopefully,

673
00:36:02,000 --> 00:36:05,000
kwa sababu TMP ni kwenda kupewa thamani ya.

674
00:36:05,000 --> 00:36:08,000
>> Sasa hebu gani magazeti, magazeti b,

675
00:36:08,000 --> 00:36:11,000
lakini sasa magazeti TMP, na ni kweli 1.

676
00:36:11,000 --> 00:36:14,000
Hebu kufanya ijayo. Hebu kufanya ijayo.

677
00:36:14,000 --> 00:36:16,000
Nimekuwa kumaliza kazi byta.

678
00:36:16,000 --> 00:36:19,000
Mimi bado ndani yake katika mstari 40, hivyo basi mimi magazeti,

679
00:36:19,000 --> 00:36:22,000
magazeti b, na mimi sijali nini TMP ni.

680
00:36:22,000 --> 00:36:27,000
Inaonekana kama byta ni sahihi linapokuja swapping b na.

681
00:36:27,000 --> 00:36:31,000
Lakini kama mimi sasa aina ya pili, mimi kuruka nyuma ya mstari 25,

682
00:36:31,000 --> 00:36:34,000
na bila shaka, kama mimi aina katika x na y magazeti

683
00:36:34,000 --> 00:36:38,000
wao uko bado unchanged, hivyo tuna si fasta tatizo.

684
00:36:38,000 --> 00:36:41,000
Lakini diagnostically sasa labda na mpango huu GDB

685
00:36:41,000 --> 00:36:44,000
tumekuwa angalau kujipatia hatua moja karibu na uelewa

686
00:36:44,000 --> 00:36:47,000
nini kinaendelea vibaya bila ya kuwa na takataka code yetu kwa kuweka printf hapa,

687
00:36:47,000 --> 00:36:50,000
printf hapa, printf hapa na kisha kukimbia tena na tena

688
00:36:50,000 --> 00:36:52,000
kujaribu kufikiri nini kinaendelea vibaya.

689
00:36:52,000 --> 00:36:55,000
>> Mimi nina kwenda mbele na kuacha nje ya hii kabisa na kuacha.

690
00:36:55,000 --> 00:36:57,000
Ni kwenda basi sema, "Simamisha anyway?" Ndiyo.

691
00:36:57,000 --> 00:37:00,000
Sasa mimi nina nyuma katika haraka yangu ya kawaida, na mimi nina kufanyika kwa kutumia GDB.

692
00:37:00,000 --> 00:37:03,000
Kama kando, huna haja ya kutumia hii-tui bendera.

693
00:37:03,000 --> 00:37:07,000
Kwa kweli, kama wewe ni omit kupata kimsingi nusu chini ya screen.

694
00:37:07,000 --> 00:37:11,000
Kama mimi basi aina ya mapumziko kuu na kisha kukimbia

695
00:37:11,000 --> 00:37:15,000
Mimi bado anaweza kuendesha programu yangu, lakini nini kufanya ni zaidi textually

696
00:37:15,000 --> 00:37:18,000
nionyeshe sasa line moja kwa wakati mmoja.

697
00:37:18,000 --> 00:37:21,000
Tui-, textual user interface,

698
00:37:21,000 --> 00:37:25,000
tu inaonyesha zaidi ya mpango wa saa moja, ambayo pengine ni kidogo conceptually rahisi.

699
00:37:25,000 --> 00:37:27,000
Lakini kwa kweli, mimi wanaweza tu kufanya ijayo, pili, pili,

700
00:37:27,000 --> 00:37:30,000
na mimi naenda kuona mstari mmoja kwa wakati, na kama kweli wanataka kuona nini kinaendelea

701
00:37:30,000 --> 00:37:35,000
Mimi unaweza aina orodha na kuona rundo zima la mistari jirani.

702
00:37:35,000 --> 00:37:39,000
>> Kuna video ambayo tumekuwa aliuliza kwamba wewe kuangalia kwa tatizo seti 3

703
00:37:39,000 --> 00:37:43,000
ambayo inashughulikia Nate baadhi ya intricacies ya GDB,

704
00:37:43,000 --> 00:37:46,000
na hii ni moja ya mambo hayo, uaminifu, ambapo baadhi ya asilimia zisizo trivial ya wewe

705
00:37:46,000 --> 00:37:49,000
kamwe kugusa GDB, na kwamba itakuwa kitu mbaya

706
00:37:49,000 --> 00:37:53,000
kwa sababu literally wewe kuishia kutumia muda zaidi baadaye huu muhula

707
00:37:53,000 --> 00:37:56,000
Chasing chini mende basi ingekuwa kama wewe kuweka katika kwamba nusu saa / saa

708
00:37:56,000 --> 00:38:00,000
wiki hii na kujifunza ijayo kwa kupata starehe na GDB.

709
00:38:00,000 --> 00:38:02,000
Printf alikuwa rafiki yako.

710
00:38:02,000 --> 00:38:05,000
GDB lazima sasa kuwa rafiki yako.

711
00:38:05,000 --> 00:38:08,000
>> Maswali yoyote juu ya GDB?

712
00:38:08,000 --> 00:38:12,000
Na hapa ni orodha ya haraka ya baadhi ya amri nguvu zaidi na muhimu.

713
00:38:12,000 --> 00:38:15,000
Yeah. >> Je, unaweza magazeti kamba?

714
00:38:15,000 --> 00:38:17,000
Je, unaweza magazeti kamba? Kabisa.

715
00:38:17,000 --> 00:38:19,000
Haina tu kuwa integers.

716
00:38:19,000 --> 00:38:22,000
Kama s kutofautiana ni string aina tu katika s magazeti.

717
00:38:22,000 --> 00:38:24,000
Ni kuonyesha nini kwamba variable string ni.

718
00:38:24,000 --> 00:38:26,000
[Inaudible-mwanafunzi]

719
00:38:26,000 --> 00:38:28,000
Nitakupa anuani na kamba yenyewe.

720
00:38:28,000 --> 00:38:32,000
Ni nitakuonyesha zote mbili.

721
00:38:32,000 --> 00:38:34,000
Na jambo moja la mwisho, kwa sababu tu hizi ni nzuri kujua pia.

722
00:38:34,000 --> 00:38:37,000
Backtrace na sura, basi mimi kupiga mbizi katika wakati huu wa mwisho,

723
00:38:37,000 --> 00:38:39,000
sawa exact mpango na GDB.

724
00:38:39,000 --> 00:38:44,000
Hebu kwenda mbele na kukimbia textual user interface version,

725
00:38:44,000 --> 00:38:46,000
kuvunja kuu.

726
00:38:46,000 --> 00:38:49,000
Hebu kwenda mbele na kukimbia tena. Mimi hapa.

727
00:38:49,000 --> 00:38:55,000
Sasa basi mimi kwenda ijayo, pili, pili, pili, pili, hatua, kuingia.

728
00:38:55,000 --> 00:39:00,000
>> Na sasa nadhani nina sasa katika byta makusudi, lakini nina kama "Damn, nini ilikuwa thamani ya x?"

729
00:39:00,000 --> 00:39:02,000
Mimi siwezi kufanya x tena.

730
00:39:02,000 --> 00:39:05,000
Mimi siwezi kufanya y sababu wao siyo katika upeo.

731
00:39:05,000 --> 00:39:07,000
Hawako katika mazingira, lakini hakuna tatizo.

732
00:39:07,000 --> 00:39:09,000
Mimi unaweza aina backtrace.

733
00:39:09,000 --> 00:39:13,000
Hiyo inaonyesha yangu yote ya kazi ya kwamba haijanyonga hadi hatua hii kwa wakati.

734
00:39:13,000 --> 00:39:16,000
Ona kwamba moja juu ya chini, kuu, yanaendana na kuu

735
00:39:16,000 --> 00:39:18,000
kuwa juu ya chini ya picha yetu hapa.

736
00:39:18,000 --> 00:39:22,000
ukweli kwamba byta ni juu ya mistari yake juu na byta kuwa juu yake katika kumbukumbu hapa,

737
00:39:22,000 --> 00:39:26,000
na kama nataka kupata nyuma kuu kwa muda naweza kusema "frame."

738
00:39:26,000 --> 00:39:30,000
Nini namba? Kuu ni sura # 1.

739
00:39:30,000 --> 00:39:32,000
Mimi nina kwenda mbele na kusema "sura 1."

740
00:39:32,000 --> 00:39:36,000
>> Sasa mimi nina nyuma katika kuu, na mimi unaweza magazeti x, na mimi unaweza magazeti y,

741
00:39:36,000 --> 00:39:40,000
lakini siwezi magazeti b au.

742
00:39:40,000 --> 00:39:43,000
Lakini siwezi kusema kama mimi, "Sawa, kusubiri dakika alikuwa wapi byta.?"

743
00:39:43,000 --> 00:39:46,000
Hebu kwenda mbele na kusema "frame 0."

744
00:39:46,000 --> 00:39:48,000
Sasa mimi nina nyuma ambapo mimi nataka kuwa, na kama kando,

745
00:39:48,000 --> 00:39:52,000
kuna amri nyingine pia, kama kama wewe ni kweli kupata kuchoka kuandika ijayo, pili, pili, pili,

746
00:39:52,000 --> 00:39:56,000
unaweza ujumla kusema mambo kama "10 ijayo," na kwamba hatua kupitia mistari 10 ijayo.

747
00:39:56,000 --> 00:39:59,000
Unaweza pia kuandika "kuendelea" wakati kweli kupata kulishwa juu na wanazidi kwa njia hiyo.

748
00:39:59,000 --> 00:40:05,000
Endelea kukimbia programu yako bila usumbufu mpaka hits mwingine breakpoint,

749
00:40:05,000 --> 00:40:07,000
iwe katika kitanzi au chini chini katika mpango wako.

750
00:40:07,000 --> 00:40:11,000
>> Katika kesi hii sisi iliendelea hadi mwisho, na mpango exited kawaida.

751
00:40:11,000 --> 00:40:13,000
Hii ni njia dhana tu, duni mchakato.

752
00:40:13,000 --> 00:40:16,000
Tu programu yako exited kawaida.

753
00:40:16,000 --> 00:40:24,000
Zaidi juu ya kwamba katika video na katika vikao debugging kuja.

754
00:40:24,000 --> 00:40:26,000
Hiyo ilikuwa mengi.

755
00:40:26,000 --> 00:40:35,000
Hebu yetu 5-dakika kuvunja hapa, na tutaweza kurudi pamoja na structs files.

756
00:40:35,000 --> 00:40:38,000
>> Kama una dived katika pset wiki hii tayari

757
00:40:38,000 --> 00:40:41,000
utasikia kujua kwamba sisi kutumia katika code usambazaji,

758
00:40:41,000 --> 00:40:45,000
chanzo kificho kwamba sisi kutoa na wewe kama kianzio, baadhi ya mbinu mpya.

759
00:40:45,000 --> 00:40:50,000
Hasa, sisi ilianzisha hii Keyword mpya iitwayo struct, kwa muundo,

760
00:40:50,000 --> 00:40:53,000
ili tuweze kujenga vigezo customized ya aina.

761
00:40:53,000 --> 00:40:57,000
Sisi pia ilianzisha dhana ya faili pembejeo I / O, faili na pato,

762
00:40:57,000 --> 00:41:00,000
na hii ni ili tuweze kuokoa hali

763
00:41:00,000 --> 00:41:03,000
ya kinyang'anyiro bodi yako na faili kwenye disc

764
00:41:03,000 --> 00:41:06,000
ili wenzake mafundisho na naweza kuelewa

765
00:41:06,000 --> 00:41:09,000
nini kinaendelea ndani ya mpango wako bila ya kuwa na manually kucheza

766
00:41:09,000 --> 00:41:11,000
kadhaa ya michezo ya kinyang'anyiro.

767
00:41:11,000 --> 00:41:13,000
Tunaweza kufanya hili zaidi automatedly.

768
00:41:13,000 --> 00:41:18,000
>> Wazo hili la struct kutatua tatizo uungwana kulazimisha.

769
00:41:18,000 --> 00:41:21,000
Tuseme kwamba tunataka kutekeleza baadhi ya mpango

770
00:41:21,000 --> 00:41:25,000
kwamba kwa namna fulani anaendelea kufuatilia kwa taarifa juu ya wanafunzi,

771
00:41:25,000 --> 00:41:28,000
na wanafunzi wanaweza kuwa, kwa mfano, kitambulisho, jina

772
00:41:28,000 --> 00:41:31,000
na nyumba katika mahali kama Harvard, hivyo hizi ni vipande 3 wa habari

773
00:41:31,000 --> 00:41:34,000
tunataka kuweka karibu, hivyo basi mimi kwenda mbele na kuanza kuandika mpango kidogo hapa,

774
00:41:34,000 --> 00:41:38,000
pamoja stdio.h.

775
00:41:38,000 --> 00:41:42,000
Basi mimi kufanya ni pamoja na cs50.h.

776
00:41:42,000 --> 00:41:44,000
Na kisha kuanza kazi yangu kuu.

777
00:41:44,000 --> 00:41:46,000
Nami bother na hoja yoyote mstari amri,

778
00:41:46,000 --> 00:41:49,000
na hapa mimi nataka kuwa mwanafunzi, hivyo mimi nina kwenda kusema

779
00:41:49,000 --> 00:41:54,000
mwanafunzi ana jina, hivyo mimi nina kwenda kusema "string jina."

780
00:41:54,000 --> 00:41:59,000
Kisha mimi nina kwenda kusema mwanafunzi pia ina ID, hivyo int id,

781
00:41:59,000 --> 00:42:03,000
na mwanafunzi ana nyumba, hivyo nina pia kwenda kusema "kamba ya nyumba."

782
00:42:03,000 --> 00:42:06,000
Basi mimi itabidi ili hawa wadogo zaidi cleanly kama hii.

783
00:42:06,000 --> 00:42:11,000
Okay, sasa nina vigezo 3 na ambayo kwa kuwakilisha mwanafunzi, hivyo "mwanafunzi."

784
00:42:11,000 --> 00:42:15,000
>> Na sasa nataka populate maadili haya, hivyo basi mimi kwenda mbele na kusema kitu kama

785
00:42:15,000 --> 00:42:18,000
"Id = 123."

786
00:42:18,000 --> 00:42:21,000
Jina ni kwenda kupata Daudi.

787
00:42:21,000 --> 00:42:24,000
Hebu sema nyumba ni kwenda kupata Mather,

788
00:42:24,000 --> 00:42:31,000
na kisha mimi naenda kufanya kitu kiholela kama printf ("% s,

789
00:42:31,000 --> 00:42:37,000
ambao ni ID% d, anaishi katika% s.

790
00:42:37,000 --> 00:42:41,000
Na sasa, je, nataka kuziba katika hapa, moja baada ya nyingine?

791
00:42:41,000 --> 00:42:47,000
Jina, id, nyumba; kurudi 0.

792
00:42:47,000 --> 00:42:50,000
Okay, isipokuwa mimi Star up mahali fulani hapa

793
00:42:50,000 --> 00:42:54,000
Nadhani tuna mpango pretty nzuri kwamba maduka ya mwanafunzi mmoja.

794
00:42:54,000 --> 00:42:57,000
Bila shaka, hii si yote ya kuvutia. Nini kama mimi nataka kuwa na wanafunzi 2?

795
00:42:57,000 --> 00:42:59,000
Hiyo ni hakuna mpango mkubwa. Mimi inaweza kusaidia watu 2.

796
00:42:59,000 --> 00:43:03,000
Hebu kwenda mbele na kuonyesha hii na kwenda chini hapa,

797
00:43:03,000 --> 00:43:09,000
na naweza kusema "id = 456" kwa mtu kama Rob ambaye anaishi katika Kirkland.

798
00:43:09,000 --> 00:43:12,000
>> Okay, kusubiri, lakini siwezi kuwaita hawa kitu kimoja,

799
00:43:12,000 --> 00:43:15,000
na inaonekana kama mimi nina kwenda kuwa na nakala hii,

800
00:43:15,000 --> 00:43:19,000
hivyo basi mimi kusema kwamba hizi itakuwa Daudi vigezo,

801
00:43:19,000 --> 00:43:23,000
na napenda kupata nakala baadhi ya hizi kwa Rob.

802
00:43:23,000 --> 00:43:27,000
Tutamwita haya ya Rob lakini hii si kwenda kufanya kazi sasa

803
00:43:27,000 --> 00:43:33,000
kwa sababu mimi-kusubiri, hebu mimi kubadili id1, NAME1 na house1.

804
00:43:33,000 --> 00:43:35,000
Rob itakuwa 2, 2.

805
00:43:35,000 --> 00:43:42,000
Mimi nimepata kubadili hili hapa, hapa, hapa, hapa, hapa, hapa.

806
00:43:42,000 --> 00:43:45,000
Kusubiri, nini kuhusu Tommy? Hebu kufanya hii tena.

807
00:43:45,000 --> 00:43:49,000
Ni wazi kama bado nadhani hii ni njia nzuri ya kufanya hili, siyo,

808
00:43:49,000 --> 00:43:52,000
hivyo nakala / kuweka mbaya.

809
00:43:52,000 --> 00:43:55,000
Lakini sisi kutatuliwa wiki hii iliyopita.

810
00:43:55,000 --> 00:43:59,000
>> Nini ilikuwa ufumbuzi yetu wakati sisi alitaka kuwa na matukio mbalimbali ya aina moja data?

811
00:43:59,000 --> 00:44:01,000
[Wanafunzi] safu.

812
00:44:01,000 --> 00:44:03,000
safu, hivyo basi mimi kujaribu safi hii up.

813
00:44:03,000 --> 00:44:07,000
Hebu kufanya baadhi ya chumba kwa ajili yangu mwenyewe kwa juu, na basi mimi badala kufanya hili hapa.

814
00:44:07,000 --> 00:44:12,000
Tutaweza kuwaita watu hawa, na badala yake nitakacho wanasema "Vitambulisho int,"

815
00:44:12,000 --> 00:44:14,000
na mimi naenda kwa msaada wa 3 wa sisi kwa sasa.

816
00:44:14,000 --> 00:44:18,000
Mimi nina kwenda kusema "majina kamba," na mimi itabidi kusaidia 3 wa kwetu,

817
00:44:18,000 --> 00:44:22,000
na kisha nitakacho wanasema "nyumba kamba," na mimi nina kwenda kwa msaada 3 ya kwetu.

818
00:44:22,000 --> 00:44:26,000
Sasa katika hapa badala ya Daudi kupata vigezo yake mwenyewe mitaa

819
00:44:26,000 --> 00:44:28,000
tunaweza kujikwamua wale.

820
00:44:28,000 --> 00:44:30,000
Kwamba anajisikia vizuri kwamba sisi ni kusafisha hii up.

821
00:44:30,000 --> 00:44:35,000
Naweza kusema basi Daudi ni kwenda kuwa [0] na majina [0]

822
00:44:35,000 --> 00:44:38,000
na nyumba [0].

823
00:44:38,000 --> 00:44:41,000
Na kisha Rob tunaweza vile vile ila kwenye hili.

824
00:44:41,000 --> 00:44:46,000
Hebu kuweka hii hapa chini, hivyo yeye kwenda kiholela kuwa Vitambulisho [1].

825
00:44:46,000 --> 00:44:50,000
Yeye anaenda kuwa majina [1],

826
00:44:50,000 --> 00:44:53,000
na kisha mwishowe, nyumba [1].

827
00:44:53,000 --> 00:44:57,000
>> Bado kidogo tedious, na sasa mimi kuwa na takwimu hii nje,

828
00:44:57,000 --> 00:45:03,000
hivyo hebu kusema "majina [0], id [0], nyumba [0],

829
00:45:03,000 --> 00:45:06,000
na hebu pluralize hii.

830
00:45:06,000 --> 00:45:09,000
Vitambulisho, IDS, Vitambulisho.

831
00:45:09,000 --> 00:45:12,000
Na tena, mimi nina kufanya hivyo, hivyo tena, mimi niko tayari kutegemea nakala / kuweka tena,

832
00:45:12,000 --> 00:45:14,000
hivyo ni tabia mbaya kuna ufumbuzi mwingine hapa.

833
00:45:14,000 --> 00:45:18,000
Mimi pengine unaweza safi hii juu zaidi na kitanzi au kitu kama hicho,

834
00:45:18,000 --> 00:45:21,000
hivyo katika muda mfupi, ni kidogo bora lakini bado anahisi kama

835
00:45:21,000 --> 00:45:24,000
Mimi nina kutegemea nakala / kuweka, lakini hata hii, mimi kudai,

836
00:45:24,000 --> 00:45:27,000
si kweli kimsingi ufumbuzi wa haki kwa sababu

837
00:45:27,000 --> 00:45:29,000
nini kama wakati mwingine sisi kuamua unajua nini?

838
00:45:29,000 --> 00:45:32,000
Sisi kwa kweli lazima wamekuwa kuhifadhi anwani ya barua pepe kwa Daudi na Rob

839
00:45:32,000 --> 00:45:34,000
na kila mtu mwingine katika mpango huu.

840
00:45:34,000 --> 00:45:36,000
Tunapaswa pia kuhifadhi namba za simu.

841
00:45:36,000 --> 00:45:39,000
Tunapaswa pia kuhifadhi namba za kuwasiliana na dharura.

842
00:45:39,000 --> 00:45:41,000
Tuna haya yote vipande ya data kwamba tunataka kuhifadhi,

843
00:45:41,000 --> 00:45:43,000
hivyo ni jinsi gani wewe kwenda juu ya kufanya hivyo?

844
00:45:43,000 --> 00:45:46,000
>> Wewe kutangaza mwingine safu ya juu, na kisha wewe mwenyewe kuongeza

845
00:45:46,000 --> 00:45:49,000
anuani ya barua pepe [0], anwani ya barua pepe [1]

846
00:45:49,000 --> 00:45:51,000
kwa Daudi na Rob na kadhalika.

847
00:45:51,000 --> 00:45:56,000
Lakini kuna kweli tu dhana ya msingi ya design hii

848
00:45:56,000 --> 00:45:59,000
kwamba mimi ni kwa kutumia mfumo wa heshima kujua kuwa

849
00:45:59,000 --> 00:46:03,000
[I] katika kila moja ya arrays kadhaa

850
00:46:03,000 --> 00:46:06,000
tu hivyo hutokea kwa kutaja mtu mmoja,

851
00:46:06,000 --> 00:46:10,000
hivyo [0] katika Vitambulisho ni namba 123,

852
00:46:10,000 --> 00:46:13,000
na mimi nina kwenda kudhani kwamba majina [0]

853
00:46:13,000 --> 00:46:16,000
ni jina la mtu huyo na nyumba [0]

854
00:46:16,000 --> 00:46:21,000
ni nyumba ya mtu huyo na hivyo nje kwa wote wa arrays mbalimbali kwamba mimi kujenga.

855
00:46:21,000 --> 00:46:24,000
Lakini ona kwamba hakuna uhusiano wa kimsingi

856
00:46:24,000 --> 00:46:27,000
miongoni mwa wale vipande 3 wa habari, jina id, na nyumba,

857
00:46:27,000 --> 00:46:32,000
hata kama chombo tunajaribu mfano katika mpango huu ni si arrays.

858
00:46:32,000 --> 00:46:35,000
Arrays ni tu njia hii ya programu ya kufanya hili.

859
00:46:35,000 --> 00:46:38,000
Nini sisi kweli unataka kwa mfano katika mpango wetu ni mtu

860
00:46:38,000 --> 00:46:41,000
kama Daudi, mtu kama Rob ndani ambayo

861
00:46:41,000 --> 00:46:46,000
au encapsulating ni jina na ID na nyumba.

862
00:46:46,000 --> 00:46:49,000
>> Je, sisi kwa namna fulani kueleza wazo hili la encapsulation

863
00:46:49,000 --> 00:46:52,000
ambapo mtu ana ID, jina na nyumba

864
00:46:52,000 --> 00:46:55,000
na si mapumziko kwa kweli hack hii ambapo sisi tu

865
00:46:55,000 --> 00:46:58,000
imani kwamba kitu bracket

866
00:46:58,000 --> 00:47:02,000
inahusu chombo huo binadamu katika kila moja ya arrays haya disparate?

867
00:47:02,000 --> 00:47:04,000
Tunaweza kweli kufanya hili.

868
00:47:04,000 --> 00:47:08,000
Hebu kwenda juu kuu kwa sasa, na hebu kuunda yangu data mwenyewe aina

869
00:47:08,000 --> 00:47:10,000
kwa kweli mara ya kwanza.

870
00:47:10,000 --> 00:47:14,000
Sisi kutumika mbinu hii katika kinyang'anyiro,

871
00:47:14,000 --> 00:47:17,000
lakini hapa mimi nina kwenda mbele na kujenga aina data,

872
00:47:17,000 --> 00:47:19,000
na unajua nini, Mimi naenda kuwaita kuwa ni mwanafunzi au mtu,

873
00:47:19,000 --> 00:47:23,000
na mimi naenda kutumia typedef kwa kufafanua aina.

874
00:47:23,000 --> 00:47:25,000
Mimi naenda kusema kwamba hii ni muundo,

875
00:47:25,000 --> 00:47:29,000
na kisha muundo huu ni kwenda kuwa mwanafunzi wa aina, tutaweza kusema,

876
00:47:29,000 --> 00:47:31,000
hata kama ni kidogo dated sasa kwa ajili yangu.

877
00:47:31,000 --> 00:47:33,000
Tutaweza kusema "int id."

878
00:47:33,000 --> 00:47:35,000
Tutaweza kusema "string jina."

879
00:47:35,000 --> 00:47:37,000
Kisha tutaweza kusema "string nyumba,"

880
00:47:37,000 --> 00:47:40,000
hivyo sasa na mwisho wa mistari hii michache ya maadili ya

881
00:47:40,000 --> 00:47:45,000
I have just kufundishwa Clang kuwa kuna

882
00:47:45,000 --> 00:47:49,000
data aina badala ints, badala ya masharti, badala ya mara mbili, badala inaelea.

883
00:47:49,000 --> 00:47:54,000
>> Kama wa wakati huu katika muda mstari 11, sasa kuna data mpya ya aina inayoitwa wanafunzi,

884
00:47:54,000 --> 00:47:58,000
na sasa siwezi kutangaza variable mwanafunzi popote nataka,

885
00:47:58,000 --> 00:48:01,000
hivyo basi mimi kitabu chini hapa watu.

886
00:48:01,000 --> 00:48:05,000
Sasa naweza kujikwamua hii, na mimi siwezi kwenda nyuma chini ya Daudi hapa,

887
00:48:05,000 --> 00:48:10,000
na kwa Daudi kweli mimi kusema kwamba Daudi,

888
00:48:10,000 --> 00:48:13,000
tunaweza literally jina variable baada ya mwenyewe,

889
00:48:13,000 --> 00:48:16,000
ni kwenda kuwa mwanafunzi wa aina.

890
00:48:16,000 --> 00:48:18,000
Hii inaweza kuangalia weird kidogo, lakini hii si wote tofauti

891
00:48:18,000 --> 00:48:22,000
kutoka kutangaza kitu kama int au kamba au kamba ya kuelea.

892
00:48:22,000 --> 00:48:24,000
Ni tu hivyo hutokea kuitwa mwanafunzi sasa,

893
00:48:24,000 --> 00:48:28,000
na kama nataka kuweka kitu ndani ya muundo huu

894
00:48:28,000 --> 00:48:31,000
Mimi sasa kutumia kipande mpya ya syntax, lakini ni pretty moja kwa moja,

895
00:48:31,000 --> 00:48:39,000
david.id = 123, david.name = "Daudi" katika mji mkuu wa D,

896
00:48:39,000 --> 00:48:42,000
na david.house = "Mather,"

897
00:48:42,000 --> 00:48:46,000
na sasa naweza kujikwamua mambo haya hapa.

898
00:48:46,000 --> 00:48:51,000
ILANI tumekuwa sasa redesigned mpango wetu katika njia ya kweli bora zaidi

899
00:48:51,000 --> 00:48:54,000
kwa kuwa sasa mpango wetu vioo ulimwengu halisi.

900
00:48:54,000 --> 00:48:57,000
>> Kuna dhana halisi ya dunia ya mtu au mwanafunzi.

901
00:48:57,000 --> 00:49:02,000
Hapa tuna sasa version C ya mtu au zaidi hasa mwanafunzi.

902
00:49:02,000 --> 00:49:05,000
Ndani ya mtu kwamba ni tabia hizi husika,

903
00:49:05,000 --> 00:49:10,000
ID, jina na nyumba, hivyo Rob kimsingi inakuwa kitu kimoja hapa chini,

904
00:49:10,000 --> 00:49:14,000
hivyo mwanafunzi kuwaibia, na sasa rob.id = 456,

905
00:49:14,000 --> 00:49:17,000
rob.name = "Rob."

906
00:49:17,000 --> 00:49:20,000
ukweli kwamba variable inaitwa Rob ni ya aina ya maana.

907
00:49:20,000 --> 00:49:22,000
Tungeweza kuitwa ni x au y au z.

908
00:49:22,000 --> 00:49:25,000
Sisi tu jina hilo Rob kuwa semantically thabiti,

909
00:49:25,000 --> 00:49:28,000
lakini kwa kweli ni jina ndani ya lile shamba yenyewe,

910
00:49:28,000 --> 00:49:30,000
hivyo sasa nina hii.

911
00:49:30,000 --> 00:49:33,000
Hii pia haina kujisikia kama kubuni bora katika kwamba nimepata ngumu coded Daudi.

912
00:49:33,000 --> 00:49:35,000
Nimekuwa ngumu coded Rob.

913
00:49:35,000 --> 00:49:39,000
Na mimi bado wana mapumziko kwa nakala baadhi na kuweka kila wakati nataka vigezo mpya.

914
00:49:39,000 --> 00:49:43,000
Aidha, nina inaonekana kutoa kila ya vigezo hivi jina,

915
00:49:43,000 --> 00:49:46,000
hata kama ningependa badala kiasi kuelezea vigezo hizi

916
00:49:46,000 --> 00:49:48,000
 zaidi generically kama wanafunzi.

917
00:49:48,000 --> 00:49:52,000
>> Sasa tunaweza kuunganisha mawazo kwamba wamekuwa wakifanya kazi vizuri kwa ajili yetu

918
00:49:52,000 --> 00:49:56,000
na badala yake kusema, "Unajua nini, nipe variable wanafunzi walioitwa,

919
00:49:56,000 --> 00:50:01,000
na hebu kuwa ni ya kawaida 3, "hivyo sasa siwezi refine hii zaidi,

920
00:50:01,000 --> 00:50:04,000
kujikwamua Daudi manually alitangaza,

921
00:50:04,000 --> 00:50:08,000
na mimi unaweza badala kusema kitu kama wanafunzi [0] hapa.

922
00:50:08,000 --> 00:50:11,000
Naweza kusema kisha wanafunzi [0] hapa,

923
00:50:11,000 --> 00:50:14,000
wanafunzi [0] hapa, na kadhalika, na mimi siwezi kwenda karibu

924
00:50:14,000 --> 00:50:16,000
na safi kuwa hadi kwa Rob.

925
00:50:16,000 --> 00:50:19,000
Mimi naweza pia kwenda juu sasa labda kuongeza kitanzi

926
00:50:19,000 --> 00:50:23,000
na kutumia GetString na GetInt kwa kweli kupata maadili haya kutoka kwa mtumiaji.

927
00:50:23,000 --> 00:50:27,000
Ningeweza kwenda mara kwa mara kuhusu kuongeza kwa sababu hii ni kwa ujumla mbaya mazoezi

928
00:50:27,000 --> 00:50:29,000
kwa kificho ngumu baadhi idadi holela kama 3 hapa hapa

929
00:50:29,000 --> 00:50:33,000
na kisha kumbuka tu kwamba unapaswa kuweka wanafunzi wasiozidi 3 ndani yake.

930
00:50:33,000 --> 00:50:36,000
Ni pengine ingekuwa bora kutumia # define ya wakati juu ya faili yangu

931
00:50:36,000 --> 00:50:40,000
na sababu ya kwamba nje, hivyo kweli kweli, basi mimi kwenda mbele na generalize hii.

932
00:50:40,000 --> 00:50:43,000
>> Hebu kufungua mfano kwamba kati ya leo

933
00:50:43,000 --> 00:50:46,000
mifano mapema, structs1.

934
00:50:46,000 --> 00:50:49,000
Hii ni programu kamili zaidi kwamba anatumia # define hapa

935
00:50:49,000 --> 00:50:51,000
na anasema sisi itawabidi wanafunzi 3 na default.

936
00:50:51,000 --> 00:50:54,000
Hapa nina kutangaza thamani ya darasa la wanafunzi,

937
00:50:54,000 --> 00:50:57,000
hivyo darasani ya wanafunzi, na sasa mimi nina kutumia kitanzi

938
00:50:57,000 --> 00:51:00,000
tu kufanya code kidogo zaidi kifahari, populate darasa

939
00:51:00,000 --> 00:51:05,000
na pembejeo mtumiaji, hivyo iterate kutoka i = 0 juu juu kwa wanafunzi, ambayo ni 3.

940
00:51:05,000 --> 00:51:07,000
Na kisha mimi kuchochea mtumiaji katika toleo hili

941
00:51:07,000 --> 00:51:10,000
 nini ID mwanafunzi, na mimi kupata kwa GetInt.

942
00:51:10,000 --> 00:51:13,000
Nini jina mwanafunzi, na kisha mimi kupata kwa GetString.

943
00:51:13,000 --> 00:51:15,000
Nini nyumba ya mwanafunzi? Mimi kupata kwa GetString.

944
00:51:15,000 --> 00:51:19,000
Na kisha chini hapa mimi tu aliamua kubadili

945
00:51:19,000 --> 00:51:22,000
jinsi mimi nina kuchapa haya na kwa kweli matumizi ya kitanzi,

946
00:51:22,000 --> 00:51:24,000
na ambaye mimi uchapishaji?

947
00:51:24,000 --> 00:51:27,000
Kulingana na maoni nina uchapishaji mtu yeyote katika Mather,

948
00:51:27,000 --> 00:51:30,000
na hiyo ni yake hivyo Rob na Tommy na kadhalika-kweli Tommy katika Mather.

949
00:51:30,000 --> 00:51:34,000
Tommy na Daudi itakuwa kuchapishwa katika kesi hii, lakini ni jinsi gani hii kazi?

950
00:51:34,000 --> 00:51:40,000
Hatujaona kazi hii kabla, lakini nadhani kuchukua kama yale hii gani.

951
00:51:40,000 --> 00:51:42,000
Inalinganishwa masharti.

952
00:51:42,000 --> 00:51:45,000
>> Ni kidogo yasiyo dhahiri jinsi inalinganishwa masharti kwa sababu ni zamu nje

953
00:51:45,000 --> 00:51:49,000
ikiwa kuirudisha 0 kwamba maana ya masharti ni sawa.

954
00:51:49,000 --> 00:51:53,000
Kama kuirudisha -1 kwamba maana ya mtu kuja alphabetically kabla nyingine,

955
00:51:53,000 --> 00:51:57,000
na kama anarudi kwamba maana ya neno 1 nyingine inakuja alphabetically

956
00:51:57,000 --> 00:52:00,000
kabla ya wengine, na unaweza kuangalia online au katika ukurasa mtu

957
00:52:00,000 --> 00:52:04,000
kuona hasa njia ambayo ni ambayo, lakini yote hii sasa ni kufanya ni kusema ni

958
00:52:04,000 --> 00:52:09,000
ikiwa [i]. nyumba ni sawa na "Mather"

959
00:52:09,000 --> 00:52:13,000
kisha kwenda mbele na magazeti nje hivyo na hivyo ni katika Mather.

960
00:52:13,000 --> 00:52:16,000
Lakini hapa ni kitu sisi hawajaona mbele, na tutaweza kurudi huu.

961
00:52:16,000 --> 00:52:21,000
Mimi si unakumbuka hata kuwa kufanya hivyo yoyote ya mipango yangu.

962
00:52:21,000 --> 00:52:24,000
Bure ni inaonekana akimaanisha kumbukumbu, kumkomboa kumbukumbu,

963
00:52:24,000 --> 00:52:31,000
lakini kile kumbukumbu mimi inaonekana kumkomboa katika kitanzi hii chini ya mpango huu?

964
00:52:31,000 --> 00:52:34,000
Inaonekana kama mimi nina kumkomboa jina la mtu

965
00:52:34,000 --> 00:52:37,000
na nyumba ya mtu, lakini kwa nini ni hivyo?

966
00:52:37,000 --> 00:52:41,000
>> Ni zinageuka wiki hizi zote kwamba tumekuwa kutumia GetString

967
00:52:41,000 --> 00:52:45,000
tumekuwa aina ya amekuwa akianzisha mdudu katika kila moja ya mipango yako.

968
00:52:45,000 --> 00:52:51,000
GetString kwa kubuni kumbukumbu inatenga hivyo kwamba wanaweza kurudi wewe kamba,

969
00:52:51,000 --> 00:52:55,000
kama Daudi, au Rob, na unaweza kisha kufanya chochote unataka

970
00:52:55,000 --> 00:52:59,000
na kwamba kamba katika mpango wako kwa sababu tumekuwa zimehifadhiwa kumbukumbu kwa ajili yenu.

971
00:52:59,000 --> 00:53:02,000
tatizo ni wakati huu wote kila wakati wewe piga GetString

972
00:53:02,000 --> 00:53:05,000
sisi, waandishi wa GetString, wamekuwa wakiuliza mfumo wa uendeshaji

973
00:53:05,000 --> 00:53:07,000
kutupatia kidogo ya RAM kwa kamba hii.

974
00:53:07,000 --> 00:53:09,000
Utupe kidogo ya RAM kwa kamba hii ijayo.

975
00:53:09,000 --> 00:53:11,000
Tupeni zaidi RAM kwa kamba hii ijayo.

976
00:53:11,000 --> 00:53:13,000
Nini wewe, programu, hawajawahi kufanya

977
00:53:13,000 --> 00:53:15,000
anatupa kwamba nyuma kumbukumbu,

978
00:53:15,000 --> 00:53:17,000
hivyo kwa muda wa wiki kadhaa haya yote ya programu ve yameandikwa

979
00:53:17,000 --> 00:53:20,000
wamekuwa na kile kinachoitwa leap kumbukumbu ambapo wanaendelea kutumia

980
00:53:20,000 --> 00:53:24,000
zaidi na zaidi kumbukumbu kila wakati wewe piga GetString, na hiyo ni faini.

981
00:53:24,000 --> 00:53:27,000
Sisi kwa makusudi kufanya hivyo katika wiki ya kwanza kwa sababu si kwamba kuvutia

982
00:53:27,000 --> 00:53:29,000
kwa kuwa na wasiwasi kuhusu ambapo string anakuja kutoka.

983
00:53:29,000 --> 00:53:34,000
Unataka wote ni neno Rob kurudi wakati mtumiaji aina hiyo in

984
00:53:34,000 --> 00:53:38,000
>> Lakini kusonga mbele kwa sasa tuna kuanza kupata kisasa zaidi kuhusu hili.

985
00:53:38,000 --> 00:53:42,000
Wakati wowote sisi kutenga kumbukumbu sisi bora hatimaye mkono ni nyuma.

986
00:53:42,000 --> 00:53:45,000
Vinginevyo katika ulimwengu wa kweli juu ya Mac au PC yako unaweza kuwa mara kwa mara na uzoefu

987
00:53:45,000 --> 00:53:50,000
dalili ambapo kompyuta yako ni ya kusaga kwa mguu hatimaye

988
00:53:50,000 --> 00:53:54,000
au kijinga inazunguka beach mpira ni tu occupying wa kompyuta

989
00:53:54,000 --> 00:53:56,000
mzima makini na huwezi kufanya mambo.

990
00:53:56,000 --> 00:54:00,000
Hiyo inaweza kuelezwa na idadi yoyote ya mende, lakini miongoni mwa wale mende iwezekanavyo

991
00:54:00,000 --> 00:54:03,000
ni mambo kuitwa kumbukumbu uvujaji ambapo mtu ambaye aliandika kwamba kipande cha programu

992
00:54:03,000 --> 00:54:07,000
unatumia hakuwa kumbuka kumbukumbu bure

993
00:54:07,000 --> 00:54:10,000
kwamba yeye au yeye aliuliza mfumo wa uendeshaji kwa,

994
00:54:10,000 --> 00:54:14,000
si kutumia GetString, kwa sababu hilo ni jambo CS50, lakini kwa kutumia kazi sawa

995
00:54:14,000 --> 00:54:16,000
kwamba kuuliza mfumo wa uendeshaji kwa ajili ya kumbukumbu.

996
00:54:16,000 --> 00:54:19,000
Kama wewe au wao screw up na kweli kamwe kurudi kwamba kumbukumbu

997
00:54:19,000 --> 00:54:24,000
dalili ya kwamba unaweza kuwa mpango kupungua na kupungua na kupungua chini

998
00:54:24,000 --> 00:54:26,000
isipokuwa wewe kumbuka kuwaita bure.

999
00:54:26,000 --> 00:54:28,000
>> Tutaweza kurudi lini na kwa nini kuita bure,

1000
00:54:28,000 --> 00:54:32,000
lakini hebu kwenda mbele tu kwa ajili ya hatua nzuri na kujaribu kuendesha programu hii hasa.

1001
00:54:32,000 --> 00:54:35,000
Hii ilikuwa inaitwa structs1, kuingia.

1002
00:54:35,000 --> 00:54:40,000
Hebu kwenda mbele na kukimbia structs1, 123, Daudi Mather,

1003
00:54:40,000 --> 00:54:47,000
456, Rob Kirkland, 789,

1004
00:54:47,000 --> 00:54:50,000
Tommy Mather, na tunaona ya Daudi katika Mather, Tommy katika Mather.

1005
00:54:50,000 --> 00:54:53,000
Hii ni kidogo tu sanity hundi kwamba mpango kazi.

1006
00:54:53,000 --> 00:54:56,000
Sasa, kwa bahati mbaya, mpango huu ni kidogo frustrating katika kuwa

1007
00:54:56,000 --> 00:55:00,000
Sikuweza kazi hiyo yote, mimi typed katika masharti 9 tofauti, enter,

1008
00:55:00,000 --> 00:55:04,000
aliambiwa ambaye alikuwa katika Mather, bado ni wazi nilijua ambaye alikuwa katika Mather tayari kwa sababu mimi niliandika hivyo.

1009
00:55:04,000 --> 00:55:07,000
Ni angalau ingekuwa nzuri kama mpango huu ni zaidi kama database

1010
00:55:07,000 --> 00:55:10,000
na ni kweli anakumbuka kile nilicho typed katika

1011
00:55:10,000 --> 00:55:12,000
hivyo mimi kamwe tena kuwa na pembejeo rekodi hizi mwanafunzi.

1012
00:55:12,000 --> 00:55:15,000
Labda ni kama mfumo registrarial.

1013
00:55:15,000 --> 00:55:21,000
>> Tunaweza kufanya hili kwa kutumia mbinu hii inajulikana kama faili pembejeo I / O, faili na pato,

1014
00:55:21,000 --> 00:55:24,000
sana njia generic ya kusema lolote wakati unataka kusoma au kuandika files files

1015
00:55:24,000 --> 00:55:26,000
unaweza kufanya hivyo kwa kuweka baadhi ya kazi.

1016
00:55:26,000 --> 00:55:29,000
Hebu kwenda mbele na kufungua hili structs2.c mfano,

1017
00:55:29,000 --> 00:55:33,000
ambayo ni karibu sawa, lakini hebu angalia nini sasa anafanya.

1018
00:55:33,000 --> 00:55:36,000
Katika juu ya faili mimi kutangaza darasa la wanafunzi.

1019
00:55:36,000 --> 00:55:38,000
Mimi kisha populate darasa na pembejeo ya mtumiaji,

1020
00:55:38,000 --> 00:55:41,000
hivyo wale mistari ya maadili ni hasa kama kabla.

1021
00:55:41,000 --> 00:55:45,000
Kisha kama mimi kitabu chini hapa mimi magazeti kila mtu ambaye ni katika Mather kiholela kama kabla,

1022
00:55:45,000 --> 00:55:47,000
lakini hii ni ya kuvutia mpya kipengele.

1023
00:55:47,000 --> 00:55:51,000
Hizi mistari ya maadili ni mpya, na wao kuanzisha kitu hapa,

1024
00:55:51,000 --> 00:55:55,000
JALADA, kila kofia, na ina * katika hapa pia.

1025
00:55:55,000 --> 00:55:58,000
Hebu hoja hii zaidi ya hapa, * juu hapa pia.

1026
00:55:58,000 --> 00:56:00,000
>> Kazi hii hatujaona kabla, fopen,

1027
00:56:00,000 --> 00:56:03,000
lakini inamaanisha faili wazi, hivyo hebu skim kupitia haya,

1028
00:56:03,000 --> 00:56:05,000
na hii ni kitu tutaweza kurudi katika psets baadaye,

1029
00:56:05,000 --> 00:56:10,000
lakini mstari huu hapa kimsingi kufungua faili inayoitwa database,

1030
00:56:10,000 --> 00:56:13,000
na hasa kuufungua hivyo kwa njia ambayo inaweza kufanya nini ni vile?

1031
00:56:13,000 --> 00:56:15,000
[Inaudible-mwanafunzi]

1032
00:56:15,000 --> 00:56:19,000
Haki, hivyo "w" tu ina maana ni kuwaambia mfumo wa uendeshaji

1033
00:56:19,000 --> 00:56:21,000
kufungua faili hii kwa njia ambayo naweza kumwandikia ni vile.

1034
00:56:21,000 --> 00:56:23,000
Sitaki kusoma. Mimi sitaki iangalie tu.

1035
00:56:23,000 --> 00:56:26,000
Nataka mabadiliko hayo na kuongeza uwezekano wa mambo hayo,

1036
00:56:26,000 --> 00:56:28,000
na faili ni kwenda kuitwa database.

1037
00:56:28,000 --> 00:56:30,000
Hii inaweza kuitwa kitu.

1038
00:56:30,000 --> 00:56:32,000
Hii inaweza kuwa database.txt. Hii inaweza kuwa. Db.

1039
00:56:32,000 --> 00:56:37,000
Hii inaweza kuwa neno kama foo, lakini mimi kiholela alichagua jina database file.

1040
00:56:37,000 --> 00:56:42,000
Hii ni kidogo sanity hundi kwamba tutaweza kurudi katika kina kubwa zaidi ya muda,

1041
00:56:42,000 --> 00:56:47,000
ikiwa fp, kwa pointer SVG, haina null sawa kwamba maana yote ni sawa.

1042
00:56:47,000 --> 00:56:51,000
>> Long hadithi fupi, kazi kama fopen wakati mwingine kushindwa.

1043
00:56:51,000 --> 00:56:53,000
Labda faili haipo. Labda wewe ni nje ya nafasi ya disc.

1044
00:56:53,000 --> 00:56:55,000
Labda huna ruhusa ya folder kwamba,

1045
00:56:55,000 --> 00:56:58,000
hivyo kama fopen anarudi kitu null mbaya kilichotokea.

1046
00:56:58,000 --> 00:57:02,000
Kinyume chake, kama fopen haina kurudi null wote ni vizuri

1047
00:57:02,000 --> 00:57:04,000
na mimi unaweza kuanza kuandika na faili hii.

1048
00:57:04,000 --> 00:57:06,000
Hapa ni hila mpya.

1049
00:57:06,000 --> 00:57:08,000
Hii ni kitanzi kwa hiyo iterating juu ya kila mmoja wa wanafunzi wangu,

1050
00:57:08,000 --> 00:57:10,000
na hii inaonekana hivyo sawa na kile ambacho tumefanya kabla,

1051
00:57:10,000 --> 00:57:15,000
lakini kazi hii ni binamu wa printf kuitwa fprintf kwa faili printf,

1052
00:57:15,000 --> 00:57:18,000
na taarifa hiyo ni tofauti katika njia tu 2.

1053
00:57:18,000 --> 00:57:20,000
Moja, ni kuanza kwa f badala ya p,

1054
00:57:20,000 --> 00:57:23,000
lakini basi hoja yake ya kwanza ni inaonekana nini?

1055
00:57:23,000 --> 00:57:25,000
[Wanafunzi] File. >> Ni faili.

1056
00:57:25,000 --> 00:57:30,000
Hii kitu inayoitwa fp, ambayo hatimaye tutaweza tease mbali kile pointer faili ni,

1057
00:57:30,000 --> 00:57:35,000
lakini kwa sasa fp tu inawakilisha faili kwamba mimi na kufunguliwa,

1058
00:57:35,000 --> 00:57:41,000
hivyo fprintf hapa ni kusema magazeti ID hii mtumiaji SVG, si kwa screen.

1059
00:57:41,000 --> 00:57:44,000
Andika jina la mtumiaji na faili, si kwa screen,

1060
00:57:44,000 --> 00:57:47,000
nyumba ya SVG, si kwa screen, na kisha chini hapa, ni wazi,

1061
00:57:47,000 --> 00:57:50,000
karibu faili, na kisha chini hapa bure kumbukumbu.

1062
00:57:50,000 --> 00:57:53,000
>> Tofauti pekee kati ya toleo hili 2 na toleo 1

1063
00:57:53,000 --> 00:57:58,000
ni kuanzishwa fopen na hii JALADA na *

1064
00:57:58,000 --> 00:58:01,000
na wazo hili la fprintf, hivyo hebu angalia nini matokeo ya mwisho ni.

1065
00:58:01,000 --> 00:58:03,000
Hebu kwenda katika terminal dirisha yangu.

1066
00:58:03,000 --> 00:58:06,000
Hebu kukimbia structs2, kuingia.

1067
00:58:06,000 --> 00:58:09,000
Inaonekana kama yote ni sawa. Hebu rerun structs2.

1068
00:58:09,000 --> 00:58:15,000
123, Daudi Mather, 456, Rob Kirkland,

1069
00:58:15,000 --> 00:58:19,000
789, Tommy Mather, kuingia.

1070
00:58:19,000 --> 00:58:23,000
Inaonekana kama ni walijivuna sawa, lakini kama mimi sasa kufanya ls

1071
00:58:23,000 --> 00:58:28,000
taarifa gani faili ni katika hapa kati yangu code yote, database,

1072
00:58:28,000 --> 00:58:32,000
hivyo hebu kufungua kwamba, gedit wa database, na kuangalia kwamba.

1073
00:58:32,000 --> 00:58:34,000
Ni si sexiest ya muundo faili.

1074
00:58:34,000 --> 00:58:38,000
Ni kweli ni moja ya kipande cha data line kwa kila mstari kwa mstari,

1075
00:58:38,000 --> 00:58:42,000
lakini wale ambao wanatumia files Excel au CSV, comma separated maadili,

1076
00:58:42,000 --> 00:58:47,000
Mimi naweza shaka kutumika kwa fprintf badala labda kufanya kitu kama hiki

1077
00:58:47,000 --> 00:58:50,000
ili mimi nilikuwa kwa kweli kujenga sawa ya faili Excel

1078
00:58:50,000 --> 00:58:53,000
kwa kutenganisha mambo kwa koma, si tu mpya mistari.

1079
00:58:53,000 --> 00:58:56,000
>> Katika kesi hii kama alikuwa na badala yake kutumika koma badala ya mistari mpya

1080
00:58:56,000 --> 00:59:01,000
Mimi nilikuwa literally kufungua faili hii database katika Excel kama mimi badala alifanya ni kuangalia kama hii.

1081
00:59:01,000 --> 00:59:03,000
Kwa kifupi, sasa kwamba tuna uwezo wa kuandika kwa files

1082
00:59:03,000 --> 00:59:07,000
tunaweza sasa kuanza data kuendelea, kuweka kuzunguka disc

1083
00:59:07,000 --> 00:59:10,000
ili tuweze kuweka habari karibu tena na tena.

1084
00:59:10,000 --> 00:59:14,000
Notice michache ya mambo mengine ambayo ni sasa kidogo zaidi familiar.

1085
00:59:14,000 --> 00:59:16,000
Katika juu ya faili hii C tuna typedef

1086
00:59:16,000 --> 00:59:21,000
kwa sababu sisi alitaka kujenga aina data kwamba inawakilisha neno,

1087
00:59:21,000 --> 00:59:25,000
hivyo aina hii inaitwa neno, na ndani ya muundo huu

1088
00:59:25,000 --> 00:59:27,000
ni kidogo fancier sasa.

1089
00:59:27,000 --> 00:59:30,000
Kwa nini ni neno linaloundwa inaonekana safu?

1090
00:59:30,000 --> 00:59:33,000
Je, ni neno tu intuitively?

1091
00:59:33,000 --> 00:59:35,000
>> Ni safu ya wahusika.

1092
00:59:35,000 --> 00:59:37,000
Ni mlolongo wa wahusika nyuma kwa nyuma kwa nyuma.

1093
00:59:37,000 --> 00:59:41,000
Barua katika kofia wote hutokea kwa kuwa sisi kiholela kusema upeo urefu

1094
00:59:41,000 --> 00:59:44,000
yoyote ya neno katika kamusi ya kwamba sisi ni kutumia kwa ajili ya kinyang'anyiro.

1095
00:59:44,000 --> 00:59:46,000
Kwa nini nina 1?

1096
00:59:46,000 --> 00:59:48,000
tabia null.

1097
00:59:48,000 --> 00:59:51,000
Kumbuka wakati sisi tulikuwa mfano Bananagrams sisi zinahitajika thamani maalum

1098
00:59:51,000 --> 00:59:55,000
mwisho wa neno ili kuweka wimbo

1099
00:59:55,000 --> 00:59:59,000
ambapo maneno ya kweli kumalizika, na kama tatizo kuweka vipimo anasema

1100
00:59:59,000 --> 01:00:03,000
hapa sisi ni kujihusisha na neno aliyopewa thamani bulin,

1101
01:00:03,000 --> 01:00:05,000
bendera, ili kuzungumza, kweli au uongo.

1102
01:00:05,000 --> 01:00:09,000
Je, umefanikiwa neno hili tayari, kwa sababu tunatambua

1103
01:00:09,000 --> 01:00:13,000
kweli tunahitaji njia ya kukumbuka si tu maana ya neno ni katika kinyang'anyiro

1104
01:00:13,000 --> 01:00:15,000
lakini kama au wewe, mwanadamu, wamegundua kuwa

1105
01:00:15,000 --> 01:00:20,000
ili kwamba kama wewe kufanya kupata neno "" huwezi aina tu, kuingia, ingieni,, kuingia

1106
01:00:20,000 --> 01:00:23,000
na kupata pointi 3, pointi 3, pointi 3, pointi 3.

1107
01:00:23,000 --> 01:00:26,000
Tunataka kuwa na uwezo wa Fukuza kwamba neno kwa kuweka bool

1108
01:00:26,000 --> 01:00:29,000
kwa kweli kama wewe ve tayari kuiona, na hivyo ndiyo sababu sisi

1109
01:00:29,000 --> 01:00:31,000
zimegawanywa katika muundo huu.

1110
01:00:31,000 --> 01:00:35,000
>> Sasa, hapa chini katika kinyang'anyiro kuna hii struct nyingine iitwayo kamusi.

1111
01:00:35,000 --> 01:00:39,000
Hayupo hapa ni neno typedef kwa sababu katika kesi hii

1112
01:00:39,000 --> 01:00:43,000
sisi zinahitajika kurejelea wazo la kamusi,

1113
01:00:43,000 --> 01:00:46,000
na kamusi ina rundo zima la maneno,

1114
01:00:46,000 --> 01:00:49,000
kama alisema kwa safu hii, na jinsi wengi wa maneno hayo yapo?

1115
01:00:49,000 --> 01:00:51,000
Naam, chochote hii variable kuitwa ukubwa anasema.

1116
01:00:51,000 --> 01:00:53,000
Lakini sisi tu haja moja kamusi.

1117
01:00:53,000 --> 01:00:55,000
Hatuna haja ya data aina ya kuitwa kamusi.

1118
01:00:55,000 --> 01:00:58,000
Sisi tu haja ya mmoja wao, hivyo ni zamu nje katika C

1119
01:00:58,000 --> 01:01:03,000
kwamba kama huna kusema typedef, wewe tu kusema struct, basi ndani ya braces curly

1120
01:01:03,000 --> 01:01:05,000
kuweka vigezo yako, basi unaweza kuweka jina.

1121
01:01:05,000 --> 01:01:09,000
Hii ni moja kutangaza variable kuitwa kamusi

1122
01:01:09,000 --> 01:01:11,000
kwamba inaonekana kama hii.

1123
01:01:11,000 --> 01:01:16,000
Kwa kulinganisha, mistari haya ni kujenga reusable data muundo kuitwa neno

1124
01:01:16,000 --> 01:01:19,000
kwamba unaweza kujenga nakala nyingi za, kama sisi aliumba

1125
01:01:19,000 --> 01:01:22,000
nyingi nakala za wanafunzi.

1126
01:01:22,000 --> 01:01:24,000
>> Je, hii hatimaye kuruhusu sisi kufanya nini?

1127
01:01:24,000 --> 01:01:30,000
Hebu nirejee nyuma katika, hebu sema, mfano rahisi kutoka mara rahisi,

1128
01:01:30,000 --> 01:01:34,000
na napenda kufungua, hebu sema, compare1.c.

1129
01:01:34,000 --> 01:01:38,000
tatizo hapa chini ya mkono ni kweli peel nyuma

1130
01:01:38,000 --> 01:01:41,000
safu ya kamba na kuanza kuchukua mbali magurudumu mafunzo haya

1131
01:01:41,000 --> 01:01:44,000
kwa sababu ni zinageuka kuwa string wakati huu wote

1132
01:01:44,000 --> 01:01:47,000
ni kama sisi aliahidi katika wiki 1 kweli tu utani,

1133
01:01:47,000 --> 01:01:51,000
kisawe kutoka maktaba CS50 kwa kitu ambacho inaonekana kidogo zaidi cryptic,

1134
01:01:51,000 --> 01:01:53,000
* Char, na tumeona nyota hii kabla.

1135
01:01:53,000 --> 01:01:55,000
Tuliiona katika muktadha wa files.

1136
01:01:55,000 --> 01:01:59,000
>> Hebu sasa kuona nini tumekuwa mafichoni hii undani kwa muda sasa.

1137
01:01:59,000 --> 01:02:02,000
Hapa ni faili inayoitwa compare1.c,

1138
01:02:02,000 --> 01:02:07,000
na inaonekana anauliza mtumiaji kwa masharti 2, s na t,

1139
01:02:07,000 --> 01:02:11,000
na kisha anajaribu kulinganisha masharti hayo kwa usawa katika mstari 26,

1140
01:02:11,000 --> 01:02:14,000
na kama uko sawa inasema, "Wewe typed kitu kimoja,"

1141
01:02:14,000 --> 01:02:17,000
na kama si sawa inasema, "Wewe typed mambo tofauti."

1142
01:02:17,000 --> 01:02:19,000
Hebu kwenda mbele na kuendesha mpango huu.

1143
01:02:19,000 --> 01:02:23,000
Hebu kwenda katika chanzo saraka yangu, kufanya compare1. Ni compiled sawa.

1144
01:02:23,000 --> 01:02:25,000
Hebu kukimbia compare1.

1145
01:02:25,000 --> 01:02:27,000
Mimi itabidi zoom katika, kuingia.

1146
01:02:27,000 --> 01:02:29,000
Kusema kitu. HELLO.

1147
01:02:29,000 --> 01:02:32,000
Mimi itabidi kusema kitu tena. HELLO.

1148
01:02:32,000 --> 01:02:34,000
Mimi dhahiri hakuwa aina ya mambo mbalimbali.

1149
01:02:34,000 --> 01:02:37,000
>> Hebu jaribu hii tena. Bye bye.

1150
01:02:37,000 --> 01:02:40,000
Dhahiri si tofauti, hivyo nini kinaendelea hapa?

1151
01:02:40,000 --> 01:02:44,000
Naam, ni nini kweli kuwa ikilinganishwa katika mstari 26?

1152
01:02:44,000 --> 01:02:46,000
[Inaudible-mwanafunzi]

1153
01:02:46,000 --> 01:02:49,000
Ndiyo, hivyo ni zinageuka kuwa kamba, data aina, ni aina ya uongo nyeupe.

1154
01:02:49,000 --> 01:02:53,000
kamba ni * Char, lakini nini ni * Char?

1155
01:02:53,000 --> 01:02:56,000
* Char, kama wanasema, ni pointer,

1156
01:02:56,000 --> 01:03:00,000
na pointer ni ufanisi anuani,

1157
01:03:00,000 --> 01:03:05,000
Jumla mahali katika kumbukumbu, na kama kutokea kwa kuwa typed katika neno kama HELLO,

1158
01:03:05,000 --> 01:03:08,000
kukumbuka kutoka mijadala ya zamani ya masharti

1159
01:03:08,000 --> 01:03:16,000
hii ni kama neno HELLO.

1160
01:03:16,000 --> 01:03:19,000
Kumbuka kwamba neno kama HELLO inaweza kuwakilishwa

1161
01:03:19,000 --> 01:03:22,000
kama safu ya wahusika kama hii

1162
01:03:22,000 --> 01:03:25,000
na kisha na tabia maalum mwishoni iitwayo tabia null,

1163
01:03:25,000 --> 01:03:27,000
kama inaashiria \.

1164
01:03:27,000 --> 01:03:29,000
Je, ni kweli kamba?

1165
01:03:29,000 --> 01:03:32,000
Ona kwamba hii ni nyingi chunks ya kumbukumbu,

1166
01:03:32,000 --> 01:03:36,000
na kwa kweli, mwisho wa ni tu inajulikana mara moja wewe kuangalia njia ya string nzima

1167
01:03:36,000 --> 01:03:38,000
kuangalia kwa tabia maalum null.

1168
01:03:38,000 --> 01:03:41,000
Lakini kama hii ni chunk ya kumbukumbu kutoka kumbukumbu ya kompyuta yangu,

1169
01:03:41,000 --> 01:03:44,000
hebu kiholela kusema kwamba kamba hii tu got bahati,

1170
01:03:44,000 --> 01:03:47,000
na got kuwekwa katika mwanzo sana ya RAM kompyuta yangu.

1171
01:03:47,000 --> 01:03:54,000
Hii ni Byte 0, 1, 2, 3, 4, 5, 6 ...

1172
01:03:54,000 --> 01:04:02,000
>> Wakati mimi kusema kitu kama GetString na mimi kufanya string s = GetString

1173
01:04:02,000 --> 01:04:04,000
nini kweli kuwa alirudi?

1174
01:04:04,000 --> 01:04:08,000
Kwa wiki hizi kadhaa iliyopita, nini kweli kuwa kuhifadhiwa katika s

1175
01:04:08,000 --> 01:04:13,000
si hii kamba per se, lakini katika kesi hii ya nini kuwa kuhifadhiwa ni

1176
01:04:13,000 --> 01:04:18,000
0 idadi sababu kile GetString ya kweli haina

1177
01:04:18,000 --> 01:04:20,000
ni haina kimwili kurudi kamba.

1178
01:04:20,000 --> 01:04:22,000
Hiyo haina kweli hata kufanya akili ya kuelewa.

1179
01:04:22,000 --> 01:04:24,000
Nini hivyo kurudi ni idadi.

1180
01:04:24,000 --> 01:04:28,000
Kwamba idadi ni anuani ya HELLO katika kumbukumbu,

1181
01:04:28,000 --> 01:04:32,000
na kamba ya basi, kama sisi Peel nyuma safu hii, kamba si kweli zipo.

1182
01:04:32,000 --> 01:04:35,000
Ni tu kurahisisha katika maktaba CS50.

1183
01:04:35,000 --> 01:04:38,000
>> Hii kweli ni kitu kinachoitwa Char *.

1184
01:04:38,000 --> 01:04:41,000
Char mantiki kwa sababu nini neno, kama HELLO?

1185
01:04:41,000 --> 01:04:44,000
Naam, ni mfululizo wa chars, mfululizo wa wahusika.

1186
01:04:44,000 --> 01:04:47,000
* Char maana anuani ya tabia,

1187
01:04:47,000 --> 01:04:50,000
hivyo ni nini maana ya kurudi kamba?

1188
01:04:50,000 --> 01:04:53,000
nzuri, rahisi njia ya kurejea kwa kamba

1189
01:04:53,000 --> 01:04:57,000
ni badala ya kujaribu kufikiri ni jinsi gani mimi kurudi ka 5 au 6 tofauti

1190
01:04:57,000 --> 01:05:01,000
napenda kurudi anuani ambayo Byte?

1191
01:05:01,000 --> 01:05:03,000
moja ya kwanza.

1192
01:05:03,000 --> 01:05:06,000
Kwa maneno mengine, nikupe anwani ya tabia katika kumbukumbu.

1193
01:05:06,000 --> 01:05:10,000
Hiyo ni nini * Char inawakilisha, anuani ya tabia moja katika kumbukumbu.

1194
01:05:10,000 --> 01:05:12,000
Wito kwamba s kutofautiana.

1195
01:05:12,000 --> 01:05:15,000
Hifadhi katika s fulani anuani, ambayo mimi kiholela alisema ni 0,

1196
01:05:15,000 --> 01:05:19,000
tu kuweka mambo rahisi, lakini katika hali halisi ni ujumla idadi kubwa.

1197
01:05:19,000 --> 01:05:21,000
>> Subiri dakika.

1198
01:05:21,000 --> 01:05:23,000
Kama wewe ni tu kunipa anuani ya tabia ya kwanza, jinsi gani mimi kujua nini anuani ni

1199
01:05:23,000 --> 01:05:25,000
wa tabia ya pili, tatu, nne na tano?

1200
01:05:25,000 --> 01:05:27,000
[Inaudible-mwanafunzi]

1201
01:05:27,000 --> 01:05:31,000
Wewe tu kujua ambapo mwisho wa kamba ni kwa njia ya hila hii Handy,

1202
01:05:31,000 --> 01:05:35,000
hivyo wakati wewe kutumia kitu kama printf, nini printf literally inachukua kama hoja yake,

1203
01:05:35,000 --> 01:05:39,000
kukumbuka kwamba sisi kutumia placeholder hii% s, na kisha kupita katika

1204
01:05:39,000 --> 01:05:41,000
variable hiyo hifadhi kamba.

1205
01:05:41,000 --> 01:05:47,000
Nini wewe kweli kupita ni anuani ya tabia ya kwanza ya kamba hiyo.

1206
01:05:47,000 --> 01:05:50,000
Printf kisha anatumia kwa kitanzi au kitanzi wakati juu ya kupokea kwamba anuani,

1207
01:05:50,000 --> 01:05:53,000
kwa mfano, 0, hivyo basi mimi kufanya hili sasa,

1208
01:05:53,000 --> 01:06:02,000
printf ("% s \ n," s);

1209
01:06:02,000 --> 01:06:07,000
Wakati mimi kuwaita printf ("% s \ n," s); nini mimi kweli kutoa printf na

1210
01:06:07,000 --> 01:06:13,000
ni anuani ya tabia ya kwanza katika s, ambayo katika kesi hii holela ni H.

1211
01:06:13,000 --> 01:06:16,000
>> Jinsi gani printf kujua nini hasa kuonyesha kwenye screen?

1212
01:06:16,000 --> 01:06:19,000
mtu ambaye kutekelezwa printf kutekelezwa kitanzi wakati au kwa kitanzi

1213
01:06:19,000 --> 01:06:23,000
kwamba anasema hana tabia hii sawa maalum null tabia?

1214
01:06:23,000 --> 01:06:25,000
Kama siyo, magazeti hayo. Vipi kuhusu hili?

1215
01:06:25,000 --> 01:06:28,000
Kama si magazeti hayo, magazeti hayo, magazeti hayo, magazeti hayo.

1216
01:06:28,000 --> 01:06:32,000
Oh, hii ni moja maalum. Acheni uchapishaji na kurudi kwa mtumiaji.

1217
01:06:32,000 --> 01:06:35,000
Na kwamba literally yote ya kinachotokea chini ya Hood,

1218
01:06:35,000 --> 01:06:38,000
na kwamba mengi ya kufungua katika siku ya kwanza ya darasa,

1219
01:06:38,000 --> 01:06:43,000
lakini kwa sasa ni kweli ya kuzuia ujenzi wa kila kitu uelewa

1220
01:06:43,000 --> 01:06:46,000
hiyo imekuwa kinaendelea ndani ya kumbukumbu ya kompyuta yetu,

1221
01:06:46,000 --> 01:06:49,000
na hatimaye tutaweza tease hii mbali na msaada kidogo

1222
01:06:49,000 --> 01:06:51,000
kutoka kwa mmoja wa marafiki zetu katika Stanford.

1223
01:06:51,000 --> 01:06:56,000
>> Profesa Nick Parlante saa Stanford amefanya hii ya ajabu video mlolongo

1224
01:06:56,000 --> 01:06:58,000
kutoka kila aina ya lugha mbalimbali ambayo ilianzisha

1225
01:06:58,000 --> 01:07:00,000
hiki kidogo Claymation tabia Binky.

1226
01:07:00,000 --> 01:07:03,000
sauti uko juu ya kusikia katika hakikisho tu chache pili sneak

1227
01:07:03,000 --> 01:07:05,000
ni ile ya profesa Stanford, na wewe ni kupata

1228
01:07:05,000 --> 01:07:07,000
5 tu au 6 sekunde ya haki hii sasa,

1229
01:07:07,000 --> 01:07:09,000
lakini hii ni note ambayo tutaweza kuhitimisha leo

1230
01:07:09,000 --> 01:07:11,000
na kuanza Jumatano.

1231
01:07:11,000 --> 01:07:15,000
Mimi kukupa Pointer Mziki na Binky, hakikisho.

1232
01:07:15,000 --> 01:07:18,000
[♪ ♪ Music] [Profesa Parlante] Hey, Binky.

1233
01:07:18,000 --> 01:07:21,000
Kuamka. Ni wakati kwa ajili ya kujifurahisha pointer.

1234
01:07:21,000 --> 01:07:24,000
[Binky] Nini hiyo? Jifunze kuhusu kuyatumia?

1235
01:07:24,000 --> 01:07:26,000
Oh, GOODY!

1236
01:07:26,000 --> 01:07:29,000
>> Sisi kuona juu ya Jumatano.

1237
01:07:29,000 --> 01:07:32,000
[CS50.TV]