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>> [Music kucheza]

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00:00:03,395 --> 00:00:11,031

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DAVID J. Malan: Hii ni kama
Freshman semina leo.

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SAWA.

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Hivyo mvua sana nje.

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Hii inaelekea kutokea juu ya Jumatano,
lakini fursa zote zaidi

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kwa maswali leo.

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Basi hebu kuanza mbali kwa kweli
na filamu katika muda tu.

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Lakini tutaweza kuanza grandly kama siku zote.

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>> Hii ni CS50, na hii
Huu ndio mwisho wa wiki 4.

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Hivyo kama wameweza milele watched
TV au movie ambayo

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kuna baadhi ya wataalam wa kompyuta na
polisi, au FBI, au baadhi ya wakala

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ni kujaribu kupata baadhi
Maana adui, vizuri, wewe wameweza

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pengine habari kujieleza "kuongeza,"
ambapo kwamba fundi fulani

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magically zooms katika kubwa
mbali kuona wahalifu

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utambulisho au idadi sahani leseni
katika hata shimmer ya kioo

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au glint ya jicho mtu.

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Hivyo kweli, hebu tuangalie
chache pazia hizo kutoka Hollywood.

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[VIDEO avspelning]

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-OK, Sasa hebu kupata nzuri kuangalia wewe.

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>> -Hold Yake.

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Kukimbia nyuma.

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>> -Wait Dakika.

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Kwenda kulia.

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>> -Kuna, Kufungia huo.

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-Kamili Screen.

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-OK, Kufungia huo.

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-Tighten Juu ya kwamba, je?

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-Vector Katika juu ya kwamba
guy na gurudumu nyuma.

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-Zoom Katika haki hapa kwenye doa hili.

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-Kwa Vifaa sahihi, picha
inaweza kuwa wazi na makali.

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-Nini Hiyo?

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-Ni Mpango kukuza.

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-Je Wewe wazi kuwa up yoyote?

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-Sijui.

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Hebu kuongeza yake.

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>> -Kuongeza Sehemu A6.

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>> -I Kuimarishwa kwa undani,
and-- nadhani kuna

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kutosha ili kuongeza,
kutolewa kwa screen yangu.

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-I Kuimarishwa kutafakari katika macho yake.

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>> -Let Ni kukimbia hii kupitia
video kukuza.

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-Edgar, Unaweza kuongeza hii?

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>> -Hang Juu.

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>> I 've ikifanya kazi katika fikra hii.

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>> -Someone Ya kutafakari.

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-Reflection.

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-Kuna Tafakari ya uso wa mtu.

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-The Kutafakari.

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-Kuna Kutafakari.

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-Zoom Katika juu ya kioo.

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-Unaweza Kuona reflection.

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-Je Wewe kuongeza picha kutoka hapa?

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-Je Wewe kuongeza naye hapa hapa?

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-Je Wewe kuongeza yake?

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Je, unaweza kuongeza yake?

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>> -Je Sisi kuongeza hii?

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>> -Je Wewe kuongeza yake?

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-Hold Juu ya pili, mimi itabidi kuongeza.

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-Zoom Katika mlango.

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-Times 10.

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-Zoom.

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-Hoja katika.

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-Zaidi.

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-Wait, Kuacha.

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-Stop.

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-Pause Yake.

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-Rotate Sisi digrii 75
karibu wima, tafadhali.

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-Stop.

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Kurudi nyuma na sehemu
kuhusu mlango, tena.

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>> -Got Picha enhancer kwamba wanaweza bitmap?

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>> -Hey, Labda tunaweza kutumia Pradeep
Sen njia ya kuona ndani ya madirisha.

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-Hii Programu ni hali ya sanaa.

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>> -The Eigenvalue ni mbali.

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>> -Kwa Haki
mchanganyiko wa algorithm

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>> Hapo ya kuchukuliwa kuondoa
algorithms ngazi ya pili,

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na siwezi matumizi yao ya
kuongeza picha hii.

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>> -Lock Juu na kupanua z-mhimili.

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>> -Kuongeza.

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>> -Kuongeza.

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>> -Kuongeza.

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-Freeze Na kuongeza.

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>> [Mwisho avspelning]

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>> DAVID J. Malan: zote haki, hivyo
wote wa wale ni kweli maneno.

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Wao ni strung tu pamoja katika
njia hiyo ni kweli si busara.

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Na, kwa kweli, CS50 na kozi kama ni
inaelekea uharibifu mengi ya TV na sinema

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kwa ajili yako.

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Kwa sababu wakati wale wataalam wa kompyuta
yanakereketa mbali sheria na kusema

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mambo dhana kama
eigenvectors, na z-mhimili,

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na idadi yoyote ya wengine
kweli suala zaidi ya kiufundi,

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wao ni kweli tu stringing
Maneno pamoja wote mara nyingi mno.

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Ni kwamba mmoja wa matumaini yetu ni kwamba,
kama athari upande wa kuchukua kozi

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kama hii, je watu zaidi katika
dunia kweli kuwa na uwezo wa kupima katika

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na tu milele hivyo kidogo kushawishi
ubora na usahihi wa filamu hizo?

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>> Kwa kweli, hebu tuangalie hali halisi.

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Hivyo hapa ni wafanyakazi picha ya
Maria, moja ya wenzetu mafundisho.

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Na kudhani yeye ni
watuhumiwa wa kitu fulani.

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Na bado, kuna Glimmer ya
baadhi kipande cha ushahidi katika macho yake,

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au katika tafakari ya miwani yake.

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Naam, kama sisi kufanya hasa kama filamu
kupendekeza, eti sisi kuvuta na "kuimarisha",

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hii ni taarifa ni kiasi gani
ni katika uso wa Maria

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wakati kukamata picha
na kwamba azimio ya awali.

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>> Na, kwa kweli, unaweza kuona dots hizi.

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Na haya ndiyo yale ni
aitwaye saizi, P-I-X-E-L-S,

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ambayo ni haki mraba kawaida
kuwa ni nukta kwamba composes picha.

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Na nyuma katika siku, na kwa kweli hata
leo na baadhi ya leo LED TV

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au LCD TV, kama nimepata
moja katika chumba yako au nyumbani,

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kama wewe kwenda juu super karibu yake, na
hasa kama ni TV kiasi fulani wakubwa,

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pengine unaweza hata kuona dots hizi
na hilo ndilo kutunga picha.

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>> Na hakuna zaidi
Maelezo zaidi kuliko huu.

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Tunaweza "kuimarisha", kwa maana ya
Ng'ombe vitu tena na aina ya

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inferring aina ya, aina ya nini
rangi lazima karibu na jicho la Maria

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hivyo kwamba siyo kweli hivyo pixelated.

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Lakini kama mimi kuendelea zooming katika, kuna
ni mtu mbaya katika macho yake.

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Kama kuwa ni wote
Maelezo tuna.

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Huwezi kujenga
Maelezo nje ya kitu chochote.

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Kuna finite tu
idadi ya vipande huko.

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>> Hivyo katika kuweka tatizo 4, ambapo
una nafasi

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kucheza na aina hii ya dunia.

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Katika kuweka tatizo 4, utasikia kuchunguza
ulimwengu wa graphics, na forensics,

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na kwa kweli kuandika kanuni
kwamba recovers waliopotea picha.

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Itabidi kuandika kificho kwamba
kuyaharibu picha zilizopo

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na hatimaye kuelewa nini
kinachoendelea chini ya Hood.

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>> Na, ni zamu nje, ni kweli
si wote kwamba ngumu.

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Kwa mfano, kama sisi alitaka
kuwakilisha smiley uso ambapo

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na saizi hizi nyeusi,
au nukta hizi nyeusi,

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vizuri, tunaweza tu kuwakilisha
wao kama kweli bitmap.

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Na kama wewe milele kusikia kwamba alikuwa
kujieleza bitmap, labda

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sasa kuanza kufanya
zaidi kidogo maana leo.

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>> Sisi tayari kujua nini kidogo ni.

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Ni 0 au 1.

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Na ramani ni tu kitu
kama kipande cha karatasi

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kwamba anatoa maelekezo na ina
labda gridi ya x- na y-kuratibu.

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Hivyo hapa ni bitmap.

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Ni ramani ya bits
ambapo 1 ni inaonekana

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kwenda kuwakilisha pixel nyeupe, na
0 ni kwenda kuwakilisha pixel nyeusi.

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Lakini tunaweza shaka flip ni kuzunguka.

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Ni kweli haina jambo hivyo
muda mrefu kama sisi ni thabiti.

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Na hapa ni jinsi gani, katika binary-- ndani ya
ya kumbukumbu ya kompyuta, au hata ndani ya

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ya faili kwenye ngumu yako
drive-- inaweza kuhifadhi

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rahisi ya picha smiley uso.

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Lakini sisi ni nini, bila shaka,
anakosa picha hii?

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Rangi, sawa?

144
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Ni dhahiri hatua inayofuata au
kukuza na kuboresha huu kwa rangi.

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Hivyo kwa bahati mbaya kwa moja tu
kidogo, 0 au 1, tunaweza kuwakilisha rangi.

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Hiyo inaweza kuwa nyekundu, au bluu, au
nyeusi, nyeupe au, au kijani, au nyekundu,

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au jozi yoyote ya rangi.

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Lakini kwa ajili ya unyenyekevu wa, tutaweza
kudhani tu nyeusi na nyeupe.

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>> Kwa hiyo kile kifikra tunahitaji kama sisi
wanataka kutekeleza rangi katika picha?

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Tufanye nini na wafanye nini?

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Kama ikiwa kikwazo hapa
ni kwamba pamoja na hata kidogo unaweza tu

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kuwakilisha nchi mbili, 0 au 1, nyeupe
au nyeusi, unataka nini cha kufanya?

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Watazamaji: Zaidi ya data.

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DAVID J. Malan: bits Zaidi,
yeah zaidi data, bits zaidi.

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Na kwa kweli, hiyo ni hasa jinsi
picha rangi ni kuwakilishwa.

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Badala ya kutumia kidogo moja,
0 au 1 kwa kila pixel, kila nukta,

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wewe tu kutumia mbalimbali.

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Labda kutumia 8, labda, zaidi ya kawaida
kutumia 24, na kwa hakika, katika kuweka tatizo

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4, je kucheza na faili
muundo ambayo inatumia 24 bits kawaida.

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>> Lakini wengi katika nyinyi ni pengine
ukoo na JPEGs.

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Kama wameweza milele kuchukuliwa
picha kwenye simu yako,

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au kupakiwa au kuona kitu juu ya
Facebook, au Flickr, idadi yoyote

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00:06:20,360 --> 00:06:24,882
ya Nje picha makao, wameweza
pengine kuona JPEG picha kabla.

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Na ni zamu nje, hii ni faili
muundo tunakwenda kutumia katika pset 4,

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ambapo wewe ni kwenda
na kupona picha

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kwamba nimepata ajali ilifutwa kutoka
kupotoshwa kadi ya kumbukumbu katika kamera,

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kama wewe.

168
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>> Na zinageuka kuwa hata kama
JPEG ni pretty sophisticated--

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ni kiasi kisasa zaidi
kuliko nukta nyeusi na nyeupe

170
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tuliona wakati iliyopita, kwa sababu kuna
algorithms kweli dhana kwamba

171
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hutumiwa kubana JPEG, hivyo
kwamba unaweza kuwa kweli ni nzuri,

172
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ubora picha lakini kwa kutumia
wachache bits.

173
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Na tutaweza kurudi kwa
compression kabla ya muda mrefu.

174
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Ni zinageuka kuwa kwanza
ka tatu katika JPEG image--

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bila kujali wewe umechukua picha
of-- ni maadili 255, 216, 255.

176
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>> Kwa maneno mengine, kama wewe tu
kuona kwamba mfano wa bits,

177
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kuwakilishwa hapa kama tatu
ka, au 24 bits jumla,

178
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na uwezekano mkubwa unaweza kudai kuwa
wewe ni kuangalia saa yake hii ya kwanza ya tatu

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ka wa JPEG.

180
00:07:15,230 --> 00:07:18,040
Na hii ni nini inayojulikana
kama saini ya JPEG.

181
00:07:18,040 --> 00:07:20,540
Mengi ya muundo faili
huko nje huwa na kuanza

182
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na mifumo fulani ya sekunde 0 na 1s,
ili Madirisha, na Mac OS, na iOS,

183
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na Android kujua ni aina gani ya faili wao
ni, pamoja na kile kinachoitwa faili

184
00:07:28,272 --> 00:07:29,730
ugani kwamba mengi ya mafaili nayo.

185
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Kama una Jpg, hiyo ni
fununu nyingine ya kompyuta.

186
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>> Basi hebu sasa tuangalie hii
zaidi kidogo kitaalam.

187
00:07:35,310 --> 00:07:37,390
Tunajua alisema
mfumo ni 0 kupitia 9.

188
00:07:37,390 --> 00:07:38,740
Tunajua mapacha ni 0 na 1.

189
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Na kama unadhani nyuma pset
0, tulikuwa na wewe kushindana na,

190
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kwa muda kidogo, kitu
aitwaye hexadecimal,

191
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ambapo una 16 ya tarakimu,
badala ya 10 au badala ya 2.

192
00:07:47,320 --> 00:07:50,405
Na tarakimu hizo, na mkataba huo,
ni 0 kupitia 9 na kisha

193
00:07:50,405 --> 00:07:55,040
kupitia f, ambapo f inawakilisha nini
idadi alisema, kama akili timamu haraka

194
00:07:55,040 --> 00:07:56,640
kuangalia?

195
00:07:56,640 --> 00:07:57,610
Hivyo, 15.

196
00:07:57,610 --> 00:08:01,390
Na lazima kuwakilisha 10, tu kwa
asili ya kuagiza kwamba nimepata huo.

197
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Ni tu mkataba holela,
lakini ni kabisa ya kiwango.

198
00:08:04,350 --> 00:08:06,870
>> Hivyo kama sisi kuangalia muundo huu
ya tatu ka hebu

199
00:08:06,870 --> 00:08:09,620
kuanza tu kuangalia ni katika
njia thabiti na jinsi

200
00:08:09,620 --> 00:08:12,450
wanasayansi wa kompyuta kwa ujumla
kuangalia na kufikiri juu ya mafaili.

201
00:08:12,450 --> 00:08:15,580
Unaweza shaka kufikiri kuhusu
mafaili katika sekunde 0 na 1s, na alisema,

202
00:08:15,580 --> 00:08:19,340
lakini katika hali halisi, sisi huwa na kutumia binary
au zaidi kwa kawaida hexadecimal--

203
00:08:19,340 --> 00:08:20,760
nyuma kutoka pset 0.

204
00:08:20,760 --> 00:08:25,857
Hivyo basi mimi kupendekeza kwamba 255, 216, na 255
ni baadhi tu ya mifumo haya ya sekunde 0 na 1s.

205
00:08:25,857 --> 00:08:28,440
Na unaweza kuangalia hii kama wewe
wanataka kufanya hesabu kutoka Wiki 0.

206
00:08:28,440 --> 00:08:30,810
Lakini, kwa sasa, tu kudhani
kwamba huyu ndiye kweli sahihi.

207
00:08:30,810 --> 00:08:33,850
Nimekuwa tu kuandikwa upya tatu alisema
idadi kama maadili tatu mapacha.

208
00:08:33,850 --> 00:08:36,100
Sasa nini mimi kwenda kufanya ni
tu kuongeza baadhi ya nafasi nyeupe,

209
00:08:36,100 --> 00:08:37,266
tu kwa ajili readability ya.

210
00:08:37,266 --> 00:08:39,940
Na taarifa, mimi nina kwenda tu
hoja mambo mbali.

211
00:08:39,940 --> 00:08:43,090
Hivyo kabla, baada, kabla, baada ya.

212
00:08:43,090 --> 00:08:46,180
Mimi nina kufanya kitu kuvutia mengine
kuliko tu kueneza mambo ya nje ili

213
00:08:46,180 --> 00:08:50,380
kwamba ilani ya kila seti ya nane
bits ni sasa seti mbili za bits nne.

214
00:08:50,380 --> 00:08:54,920
Hii ni muhimu kwa sababu hexadecimal
ni hasa mtindo

215
00:08:54,920 --> 00:09:00,930
kwa sababu kila tarakimu hexadesimoli 0 kupitia
f, au zaidi hasa 0 kupitia 15,

216
00:09:00,930 --> 00:09:03,430
inaweza kuwakilishwa
na hasa nne bits.

217
00:09:03,430 --> 00:09:07,960
Kwa maneno mengine, katika hexadesimoli kama wewe
wanataka kuwakilisha 0, ni 0000 tu,

218
00:09:07,960 --> 00:09:08,780
nne zeros.

219
00:09:08,780 --> 00:09:13,997
Na kama unataka kuwakilisha 15,
ni 1111, ambayo ni vipande vinne.

220
00:09:13,997 --> 00:09:16,080
Na kama wewe kufanya hesabu,
kama hii ni wale mahali,

221
00:09:16,080 --> 00:09:18,210
hii ni 16s mahali,
hiyo ni kwenda kutoa you--

222
00:09:18,210 --> 00:09:19,960
badala ambayo inaenda
to-- pole, katika binary,

223
00:09:19,960 --> 00:09:23,660
hiyo ni kwenda kukupa 15, ndio mahali,
mahali wawili-wawili, kikundi cha watu wane na eights mahali.

224
00:09:23,660 --> 00:09:26,821
Hivyo basi mimi kupendekeza kwamba kuwa
seti ya vipande nne upande wa kushoto

225
00:09:26,821 --> 00:09:28,070
ni nini tunakwenda kuwaita f.

226
00:09:28,070 --> 00:09:30,110
Ni idadi kubwa wewe
wanaweza kuwakilisha kwa vipande vinne.

227
00:09:30,110 --> 00:09:33,300
Na sisi tayari kujua kutoka hexadecimal,
f ni tarakimu kubwa katika hexadesimoli.

228
00:09:33,300 --> 00:09:36,020
Sisi tumepewa f mwingine huko,
mbili zaidi zaidi ya hapo.

229
00:09:36,020 --> 00:09:38,980
Na kwa sasa, tu kuchukua juu ya imani
kwamba mimi wamefanya math haki

230
00:09:38,980 --> 00:09:41,890
na kwamba nusu ya kushoto
ya bits wale, 1101,

231
00:09:41,890 --> 00:09:43,980
ni kitu kimoja kama d katika hexadesimoli.

232
00:09:43,980 --> 00:09:46,490
Na mkono wa kulia, 1000, ni tu 8.

233
00:09:46,490 --> 00:09:48,140
>> Na kwamba moja ya rahisi kuona, sawa?

234
00:09:48,140 --> 00:09:51,670
8 represents-- ni haki
chini pale pale eights.

235
00:09:51,670 --> 00:09:56,040
Hivyo tuna moja katika eights safu
na chochote katika kikundi cha watu wane, wawili-wawili au ndio.

236
00:09:56,040 --> 00:09:59,830
Hivyo sasa zaidi conventionally, binadamu huwa
kuandika hexadecimal tarakimu namna hii,

237
00:09:59,830 --> 00:10:03,000
wewe tu squish yao pamoja,
na kisha kiambishi yao na 0x.

238
00:10:03,000 --> 00:10:05,920
Ina maana chochote zaidi
fununu Visual human--

239
00:10:05,920 --> 00:10:10,350
hiyo inakuja hexadecimal value-- kwa sababu
huenda ikawa si vinginevyo kuwa dhahiri.

240
00:10:10,350 --> 00:10:13,629
>> Ambayo ni kusema, hatimaye, kwamba
mfano wa zeros na ndio,

241
00:10:13,629 --> 00:10:16,170
au mfano wa hexadecimal
tarakimu equivalently kwamba wewe ni

242
00:10:16,170 --> 00:10:18,990
kwenda kuanza kuangalia kwa
katika kuweka tatizo 4 ni Haya

243
00:10:18,990 --> 00:10:22,120
na kuweka tatizo 4 spec tutakwenda
wewe kwa njia hii katika zaidi detail--

244
00:10:22,120 --> 00:10:25,344
lakini kutambua kama aina ya arcane kama
hii ili kuangalia katika mtazamo wa kwanza,

245
00:10:25,344 --> 00:10:27,010
wewe ni kwenda kuanza kuona hii mengi.

246
00:10:27,010 --> 00:10:30,320
Na kwa kweli, hata katika GDB,
HatiJava sisi ilianzisha Jumatatu

247
00:10:30,320 --> 00:10:35,440
na Dan utangulizi katika pset 3, ni kwenda
kwa mara nyingi kuonyesha maadili hexadecimal

248
00:10:35,440 --> 00:10:39,910
sababu tu wao huwa na kuwa zaidi
kawaida kuliko alisema au mapacha

249
00:10:39,910 --> 00:10:41,157
katika ulimwengu wa kompyuta.

250
00:10:41,157 --> 00:10:42,490
Sasa hebu kuweka hii katika mazingira.

251
00:10:42,490 --> 00:10:48,040
Wengi wenu wapate kukumbuka hii
picha hapa, ambayo alikuja kutoka kile?

252
00:10:48,040 --> 00:10:51,240
Vista, hivyo hata mapema zaidi
kwamba, Windows XP alifanya kwanza hii.

253
00:10:51,240 --> 00:10:52,620
Hivyo hii ni mazingira mazuri.

254
00:10:52,620 --> 00:10:55,940
Na kwa kweli, kama wewe poke kuzunguka online--
Nadhani ni makala Wikipedia,

255
00:10:55,940 --> 00:11:00,110
eti mtu kushangaza sana akatoka
kupatikana eneo hili katika dunia kuanzisha

256
00:11:00,110 --> 00:11:02,240
wake au kamera yake katika
just place-- haki

257
00:11:02,240 --> 00:11:06,510
na hii leo inaonekana like-- lakini
ni hasa kuweka sawa.

258
00:11:06,510 --> 00:11:10,060
Picha hii, ingawa, ni katika faili
muundo inayoitwa bitmap, b-m-p.

259
00:11:10,060 --> 00:11:12,910
Na sisi ni kwenda kuchukua super
mtazamo wa haraka katika nini maana.

260
00:11:12,910 --> 00:11:17,770
>> Lakini bitmap ni njia tu mbalimbali za
anayewakilisha picha bado kutumia piseli

261
00:11:17,770 --> 00:11:19,580
katika sekunde 0 na 1s, hatimaye.

262
00:11:19,580 --> 00:11:23,282
Lakini katika mtazamo wa haraka, ina
saini zaidi ya kuvutia

263
00:11:23,282 --> 00:11:24,490
mwanzoni mwa faili.

264
00:11:24,490 --> 00:11:26,670
Siyo tatu tu
ka, badala kuna

265
00:11:26,670 --> 00:11:30,770
rundo zima la mifumo ya ka
ambazo predetermined maana.

266
00:11:30,770 --> 00:11:34,490
Kwa mfano, mahali fulani katika
kwanza ka chache ya picha bitmap

267
00:11:34,490 --> 00:11:37,440
ni kwenda kuwa ukubwa wa
picha, upana wa picha,

268
00:11:37,440 --> 00:11:40,390
urefu wa sura, hivyo
metadata muhimu, kama wewe.

269
00:11:40,390 --> 00:11:43,940
Taarifa muhimu kwamba Photoshop
au graphics yoyote mpango unatumia

270
00:11:43,940 --> 00:11:45,180
ili kweli huduma ya juu.

271
00:11:45,180 --> 00:11:47,170
>> Hivyo zaidi juu ya hili katika
Tatizo Kuweka 4, lakini hii

272
00:11:47,170 --> 00:11:49,220
ni tu kusema kwamba
mwisho wa siku

273
00:11:49,220 --> 00:11:52,390
zote muundo faili tumekuwa kutumia
kwa years-- mafaili Microsoft Word,

274
00:11:52,390 --> 00:11:55,820
Mafaili idadi, files Excel,
idadi yoyote ya muundo faili

275
00:11:55,820 --> 00:11:57,770
kwamba wanaweza kuwa na baadhi
inayojulikana faili ugani

276
00:11:57,770 --> 00:12:00,130
ni sekunde 0 na 1s tu chini ya Hood.

277
00:12:00,130 --> 00:12:02,970
Na binadamu wameamua
nini mikataba ni,

278
00:12:02,970 --> 00:12:08,340
nini mwelekeo wa sekunde 0 na 1s kuwakilisha
Neno faili dhidi faili Excel,

279
00:12:08,340 --> 00:12:10,322
dhidi ya idadi yoyote ya format nyingine faili.

280
00:12:10,322 --> 00:12:12,780
Hivyo katika pset 4, itabidi
nafasi ya kucheza na kwamba.

281
00:12:12,780 --> 00:12:14,405
>> Lakini ni nini maana ya kuwa na struct.

282
00:12:14,405 --> 00:12:18,012
Hii ni kweli segue nzuri sasa
ndani ya C, ambayo ina tu wanandoa

283
00:12:18,012 --> 00:12:20,220
sifa za ziada ambazo
sisi si inaonekana katika bado.

284
00:12:20,220 --> 00:12:24,230
Ni lugha pretty ndogo na moja ya
sifa nzuri kuhusu C ni struct.

285
00:12:24,230 --> 00:12:27,300
Kwa mfano, kama wewe
alitaka represent-- hebu

286
00:12:27,300 --> 00:12:33,690
kusema alitaka kuwa na kutofautiana kwamba
inawakilisha mwanafunzi katika mpango fulani.

287
00:12:33,690 --> 00:12:37,330
Labda walikuwa kuandika shaka
Mpango wa usajili, au msingi ununuzi

288
00:12:37,330 --> 00:12:38,870
chombo, au kitu kama hicho.

289
00:12:38,870 --> 00:12:42,922
Ni vipande vya data kuhusiana nini
kwa mwanafunzi kuwa kuja akili?

290
00:12:42,922 --> 00:12:44,880
Kama mwanafunzi ni
kuwakilishwa na kile maadili?

291
00:12:44,880 --> 00:12:45,732
Yeah?

292
00:12:45,732 --> 00:12:46,940
Una jina kama mwanafunzi.

293
00:12:46,940 --> 00:12:48,900
Nini kingine haina mwanafunzi wa kawaida na?

294
00:12:48,900 --> 00:12:49,320
>> Watazamaji: [inaudible]

295
00:12:49,320 --> 00:12:50,200
>> DAVID J. Malan: Hivyo, pole.

296
00:12:50,200 --> 00:12:50,660
>> Watazamaji: Umri.

297
00:12:50,660 --> 00:12:52,980
>> DAVID J. Malan: umri au
kuzaliwa equivalently, yep.

298
00:12:52,980 --> 00:12:53,557
Nini kingine?

299
00:12:53,557 --> 00:12:54,390
Watazamaji: ID namba?

300
00:12:54,390 --> 00:12:57,460
DAVID J. Malan: Hivyo ID idadi, labda
nambari ya simu, labda Dorm, au nyumba,

301
00:12:57,460 --> 00:12:58,670
au chuo, au kitu kama hicho.

302
00:12:58,670 --> 00:13:01,820
Idadi yoyote ya vipande vya data kwamba
unaweza kuwa katika orodha yako

303
00:13:01,820 --> 00:13:03,890
ni nini kinaweza kufafanua mwanafunzi.

304
00:13:03,890 --> 00:13:08,490
Hivyo kama sisi alitaka kufanya hivyo, katika kanuni,
tupate kufanya kitu rahisi kama hii.

305
00:13:08,490 --> 00:13:15,670
Tupate kuwa na mpango ili
ina hebu sema, int kuu (utupu).

306
00:13:15,670 --> 00:13:18,920
Na kama nataka kuwakilisha
mwanafunzi nipate kuwa, kwa mfano,

307
00:13:18,920 --> 00:13:24,330
string kuitwa jina kwa kuwa mwanafunzi,
string kuitwa Dorm kwa kuwa mwanafunzi,

308
00:13:24,330 --> 00:13:26,900
labda int kuitwa ID kwa kuwa mwanafunzi.

309
00:13:26,900 --> 00:13:30,840
Na kwa sababu mimi nina kutumia kamba, mimi
haja ya kwenda nyuma na kuweka CS50.h.

310
00:13:30,840 --> 00:13:33,300
Labda mimi nina kwenda haja stdio.h.

311
00:13:33,300 --> 00:13:38,190
Hivyo basi mimi preemptively kufanya wale na mimi nina
kwenda kuwaita student.c hii kwa sasa

312
00:13:38,190 --> 00:13:40,080
na kuokoa hii.

313
00:13:40,080 --> 00:13:44,206
>> Na sasa siwezi kufanya kitu
na vigezo hivi.

314
00:13:44,206 --> 00:13:46,830
Na sisi ni kwenda tu kuandika
kwamba kama maoni katika Pseudo kificho,

315
00:13:46,830 --> 00:13:48,829
kwa sababu si kuvutia
nini cha kufanya kwa sasa.

316
00:13:48,829 --> 00:13:51,242
OK, hivyo hii ni mpango kwamba
namna fulani maduka mwanafunzi.

317
00:13:51,242 --> 00:13:53,450
Je, nataka kufanya kama mimi
unataka kuhifadhi wanafunzi wawili?

318
00:13:53,450 --> 00:13:55,991
Hivyo silika yangu ya kwanza ni kwenda
kuwa sawa, kusubiri dakika,

319
00:13:55,991 --> 00:14:01,920
kama nina mwanafunzi mwingine kwa nini si mimi
tu kufanya kamba jina 2, kamba Dorm 2,

320
00:14:01,920 --> 00:14:04,190
int id2.

321
00:14:04,190 --> 00:14:06,540
Na tumefanya gone
chini ya barabara hii kabla

322
00:14:06,540 --> 00:14:10,890
na ilikuwa ni nini ufumbuzi wetu kwa kile inaonekana
kuwa aina ya hackish nakala kuweka

323
00:14:10,890 --> 00:14:11,555
kazi hapa?

324
00:14:11,555 --> 00:14:12,346
Watazamaji: safu.

325
00:14:12,346 --> 00:14:13,830
DAVID J. Malan: Yeah,
tunaweza kutumia safu.

326
00:14:13,830 --> 00:14:15,620
Haki hii kwa haraka sana
inakuwa unwieldy.

327
00:14:15,620 --> 00:14:18,453
Una aina ya kiholela
kuanza kumtaja wote wa vigezo hivi.

328
00:14:18,453 --> 00:14:22,190
Na wewe, binadamu, una kuweka
kufuatilia kwamba OK NAME2 sambamba

329
00:14:22,190 --> 00:14:25,060
na dorm2 sambamba na id2.

330
00:14:25,060 --> 00:14:26,200
Ni tu anakuwa fujo.

331
00:14:26,200 --> 00:14:29,350
Hivyo ni rahisi sana,
kukumbuka kutoka wiki chache zilizopita,

332
00:14:29,350 --> 00:14:34,300
kwa kuwa tu kwa kuitwa majina kamba
na labda kutupa tatu ya wale.

333
00:14:34,300 --> 00:14:36,940
Na kisha labda tuna
kamba mabweni na kuwa na

334
00:14:36,940 --> 00:14:41,900
tatu ya wale, au kwa mara kwa mara,
int Vitambulisho na kuwa na tatu ya wale.

335
00:14:41,900 --> 00:14:45,250
Lakini hata sasa hii anahisi
kidogo sloppy, haki.

336
00:14:45,250 --> 00:14:49,440
Tunazungumzia wanafunzi na bado
Mimi nina kweli makao juu ya kiwango cha chini

337
00:14:49,440 --> 00:14:50,470
utekelezaji maelezo.

338
00:14:50,470 --> 00:14:52,790
Mwanafunzi jina na mabweni na ID.

339
00:14:52,790 --> 00:14:59,814
>> Kwa nini siwezi tu kutangaza kutofautiana
aitwaye mwanafunzi na kuiita s.

340
00:14:59,814 --> 00:15:02,230
Na kama nataka mwanafunzi mwingine,
kwa nini sio mimi tu kuiita t.

341
00:15:02,230 --> 00:15:05,260
Au kama nataka rundo zima
ya wanafunzi, mbona si mimi tu

342
00:15:05,260 --> 00:15:09,740
kusema nina tabaka zima la
wanafunzi, na ni watatu kati yao.

343
00:15:09,740 --> 00:15:12,470
Kwa maneno mengine, kwa nini siwezi kuja
na data zangu aina, inayoitwa

344
00:15:12,470 --> 00:15:15,641
Wanafunzi, ndani ya ambayo ni
jina, ni ID, ni Dorm,

345
00:15:15,641 --> 00:15:16,890
ni idadi yoyote ya maeneo mengine.

346
00:15:16,890 --> 00:15:19,030
Na zinageuka wewe
unaweza kufanya hasa kwamba.

347
00:15:19,030 --> 00:15:21,850
>> Hivyo C ana kipengele hiki kinachoitwa struct.

348
00:15:21,850 --> 00:15:24,700
Hiyo ni hulka lugha hiyo
inaruhusu sisi kufanya hasa hili.

349
00:15:24,700 --> 00:15:28,370
Mimi kwenda mbele
na kufungua structs.h

350
00:15:28,370 --> 00:15:32,299
ambapo tunakwenda kuona
kufuatia ufafanuzi wa mwanafunzi.

351
00:15:32,299 --> 00:15:35,215
Ni zinageuka - na hii moja hata
rahisi kuliko moja kuwashirikisha ID

352
00:15:35,215 --> 00:15:36,080
wakati iliyopita.

353
00:15:36,080 --> 00:15:39,120
Kama unataka kuja na
data ya aina yako homemade,

354
00:15:39,120 --> 00:15:42,750
na kwa kuongeza int, na char na
kuelea na wengine wote hawa ambazo zipo,

355
00:15:42,750 --> 00:15:45,810
unaweza kufanya hivyo kwa literally
kuandika typedef struct,

356
00:15:45,810 --> 00:15:47,880
kisha baadhi braces curly,
ndani ya ambayo wewe

357
00:15:47,880 --> 00:15:51,460
orodha vigezo unataka
kujiunga na hii desturi takwimu mpya

358
00:15:51,460 --> 00:15:55,670
aina kama jina na mabweni,
na kisha baada ya braces curly

359
00:15:55,670 --> 00:15:57,860
unaweza kumpa jina kwa aina mpya data.

360
00:15:57,860 --> 00:15:59,220
Hivyo, kwa mfano, mwanafunzi.

361
00:15:59,220 --> 00:16:03,247
>> Na nini ni nzuri kuhusu hili sasa ni kwamba
kama sisi kuangalia kificho inayolingana,

362
00:16:03,247 --> 00:16:05,080
mkataba huo, kwanza
kabisa, ni kuweka hii

363
00:16:05,080 --> 00:16:08,230
katika faili inayoitwa kitu nukta h,
kichwa faili, ambayo sisi si

364
00:16:08,230 --> 00:16:09,780
kuanza kutumia wenyewe kupita kiasi.

365
00:16:09,780 --> 00:16:12,120
Lakini sisi ni kwenda kuanza
kutumia kidogo kabisa sasa.

366
00:16:12,120 --> 00:16:18,650
Na nini tunaweza kufanya na hii,
hatimaye, katika hizo mistari michache ya kificho

367
00:16:18,650 --> 00:16:22,130
ni kutangaza hasa kwamba
Aina ya data, mwanafunzi.

368
00:16:22,130 --> 00:16:23,230
Na sasa hebu kuitumia.

369
00:16:23,230 --> 00:16:27,274
>> Mimi nina kwenda sasa kwenda katika
faili inayoitwa structs1.c.

370
00:16:27,274 --> 00:16:29,440
Na hebu tuangalie
sifa chache hapa.

371
00:16:29,440 --> 00:16:32,250
Hivyo mambo hapa ni
wengi wao wakiwa wa utambuzi, na tutaweza

372
00:16:32,250 --> 00:16:35,040
kurudi kitu ambacho si
ukoo katika muda tu.

373
00:16:35,040 --> 00:16:39,880
Hii bila shaka ni pamoja na yangu mwenyewe
kichwa faili, ambayo ni mpya pia,

374
00:16:39,880 --> 00:16:42,580
isipokuwa kwa pset 3 wapi,
wanakumbuka, tuna helpers.h.

375
00:16:42,580 --> 00:16:45,150
Hivyo unaweza kukumbuka # Pamoja helpers.h.

376
00:16:45,150 --> 00:16:49,381
>> Kwa nini ingawa mimi kutumia quotes
badala ya mabano angled?

377
00:16:49,381 --> 00:16:50,630
Wakati gani mimi kuchagua kati yao?

378
00:16:50,630 --> 00:16:52,310
Karibu kila mara mimi wanaonekana
kutumia mabano angled.

379
00:16:52,310 --> 00:16:55,040
Na kisha, kwa ghafla juu ya
mstari sita mimi nina kutumia quotes mbili.

380
00:16:55,040 --> 00:16:55,860
Kwa nini huenda kuwa ni nani?

381
00:16:55,860 --> 00:16:56,700
Yeah?

382
00:16:56,700 --> 00:16:57,725
>> Watazamaji: [inaudible]

383
00:16:57,725 --> 00:16:59,350
DAVID J. Malan: Hiyo ni halisi, ni nini?

384
00:16:59,350 --> 00:17:00,559
Watazamaji: Hiyo ni katika IDE yako.

385
00:17:00,559 --> 00:17:02,475
DAVID J. Malan: Yeah,
hiyo ni katika IDE yangu halisi.

386
00:17:02,475 --> 00:17:05,690
Na hebu kukaa juu IDE, kwa sababu
hiyo ni chombo kwamba mimi nina kutumia.

387
00:17:05,690 --> 00:17:08,119
Hiyo ni katika sasa yangu
directory, hasa.

388
00:17:08,119 --> 00:17:11,647
Hivyo structs.h ni faili yangu mwenyewe
si imewekwa katika IDE,

389
00:17:11,647 --> 00:17:14,480
katika mfumo wa uendeshaji yenyewe,
badala ni katika orodha yangu ya sasa.

390
00:17:14,480 --> 00:17:16,910
Hivyo mkataba ni kama unataka
ni pamoja na mpira wa kichwa yako mwenyewe faili,

391
00:17:16,910 --> 00:17:18,200
wewe tu kutumia quotes mbili.

392
00:17:18,200 --> 00:17:23,290
>> Tufanye nini kuwaita jambo hili katika
mstari 8, kwa ujumla kuzungumza?

393
00:17:23,290 --> 00:17:25,200
Hii ni nini?

394
00:17:25,200 --> 00:17:28,220
#define kitu.

395
00:17:28,220 --> 00:17:31,040
Hii inawakilisha constants, sawa?

396
00:17:31,040 --> 00:17:33,140
Kama unataka kuwa na
thamani katika mpango wako

397
00:17:33,140 --> 00:17:35,110
kwamba matumizi yote
rundo la nyakati, ni

398
00:17:35,110 --> 00:17:39,330
nzuri mkataba na sababu nje,
kuyatangaza, na hash ishara

399
00:17:39,330 --> 00:17:43,340
kufafanua, basi, na mkataba huo, katika yote
uppercase word-- ingawa si

400
00:17:43,340 --> 00:17:45,320
madhubuti muhimu, lakini
ni mkataba wa binadamu

401
00:17:45,320 --> 00:17:47,210
capitalize constants
ili waweze kuruka nje

402
00:17:47,210 --> 00:17:50,380
saa wewe visually-- nafasi na
kisha thamani unataka kuwa

403
00:17:50,380 --> 00:17:52,250
sawa na jina kwamba mara kwa mara ya.

404
00:17:52,250 --> 00:17:56,110
Hakuna semicolon, lakini wewe tu
kufuata mfano kwamba kuna.

405
00:17:56,110 --> 00:17:57,770
>> Kwa hiyo kile ni mimi kufanya katika kanuni hii halisi.

406
00:17:57,770 --> 00:18:00,660
Basi hebu tuangalie
Mpango kuu hapa.

407
00:18:00,660 --> 00:18:04,080
Katika mstari 12 kwa sababu mimi
kuwa ni pamoja na structs.h,

408
00:18:04,080 --> 00:18:06,492
Mimi sasa magically katika wangu
ovyo mpya aina data.

409
00:18:06,492 --> 00:18:09,200
Mimi si tu kupata int,
na Char, na kuelea, na kamba,

410
00:18:09,200 --> 00:18:10,060
na rangi ya bluu na wengine.

411
00:18:10,060 --> 00:18:12,470
Mimi sasa wanapata
Aina ya mwanafunzi data.

412
00:18:12,470 --> 00:18:17,740
Hivyo katika mstari 12, mimi nina kuchanganya mbili
ideas-- moja data ya aina desturi na mbili,

413
00:18:17,740 --> 00:18:18,940
kutumia safu.

414
00:18:18,940 --> 00:18:21,700
Na hivyo katika mpango huu ikiwa
Nataka kweli kusaidia

415
00:18:21,700 --> 00:18:24,320
tatu wanafunzi mbalimbali
katika mpango wangu, mimi

416
00:18:24,320 --> 00:18:30,480
unaweza tu kusema nipe kutofautiana
aitwaye wanafunzi, kila ambayo

417
00:18:30,480 --> 00:18:32,970
ni ya aina wanafunzi, ambazo
ni wangu data aina desturi.

418
00:18:32,970 --> 00:18:35,890
Na, hasa, nipe
tatu ya wale katika safu yangu.

419
00:18:35,890 --> 00:18:37,750
>> Hivyo sasa tunafanya nini katika mpango huu?

420
00:18:37,750 --> 00:18:40,670
Hapa ni tu kwa kitanzi iterating
0-3, kwa sababu hiyo

421
00:18:40,670 --> 00:18:42,110
nini thamani ya wanafunzi ni.

422
00:18:42,110 --> 00:18:44,420
Mimi na kusababisha tu user
nipe jina mwanafunzi.

423
00:18:44,420 --> 00:18:48,090
Na kisha katika mstari 17, sisi
kuwa mstari hasa ukoo.

424
00:18:48,090 --> 00:18:50,370
Tuna rafiki yetu ya zamani
GetString juu ya haki.

425
00:18:50,370 --> 00:18:52,345
Na kipande kile cha syntax
ni inaonekana mpya,

426
00:18:52,345 --> 00:18:55,130
kama wewe sijawahi iliyowekwa katika C kabla,
na kamwe kutumika structs?

427
00:18:55,130 --> 00:18:55,510
Yeah?

428
00:18:55,510 --> 00:18:56,417
>> Watazamaji: .name.

429
00:18:56,417 --> 00:18:57,500
DAVID J. Malan: .name.

430
00:18:57,500 --> 00:19:01,220
Lakini hii si sana ya leap,
kwa sababu sasa wanafunzi mabano i

431
00:19:01,220 --> 00:19:02,590
anatoa i-th mwanafunzi.

432
00:19:02,590 --> 00:19:04,730
Na kama unataka kupiga mbizi
ndani ya muundo kwamba,

433
00:19:04,730 --> 00:19:09,490
wewe tu kutumia kipindi kimoja na
kisha jina la kutofautiana ndani,

434
00:19:09,490 --> 00:19:11,900
au mali ndani ya kwamba
unataka kupata.

435
00:19:11,900 --> 00:19:14,816
Vile vile basi, kama mimi basi kuchochea
user, nipe mwanafunzi mabweni,

436
00:19:14,816 --> 00:19:18,390
unaweza vile vile kuhifadhi kwamba
kamba katika Dorm kutofautiana ndani ya

437
00:19:18,390 --> 00:19:19,940
ya kwamba muundo mwanafunzi.

438
00:19:19,940 --> 00:19:21,410
>> Na sasa mambo kupata dhana kidogo.

439
00:19:21,410 --> 00:19:24,420
Na hii ni kwenda kuangalia
katika labda mengi kabisa hivi karibuni.

440
00:19:24,420 --> 00:19:27,970
Lakini utaona hii mbali zaidi katika pset
4, hivyo hebu tu mtazamo saa sasa.

441
00:19:27,970 --> 00:19:33,364
Ni zinageuka kuwa katika mstari 23 kupitia
38, unafikiri nini mimi nina labda kufanya?

442
00:19:33,364 --> 00:19:35,530
Nimekuwa kuondolewa maoni
kwa leo, lakini toleo

443
00:19:35,530 --> 00:19:38,660
ya maadili ya online kwa
kumbukumbu ina maoni yote.

444
00:19:38,660 --> 00:19:40,171
Je, mimi wanaonekana kuwa kufanya?

445
00:19:40,171 --> 00:19:42,530
>> Watazamaji: Kuokoa faili na kila
habari kwamba mtumiaji aliingia.

446
00:19:42,530 --> 00:19:44,530
>> DAVID J. Malan: Yeah,
hasa, hii ni njia mpya

447
00:19:44,530 --> 00:19:46,370
kwamba sisi ni kuona miwili,
Kipengele kingine cha C,

448
00:19:46,370 --> 00:19:48,700
ambapo naweza kujenga files yangu mwenyewe.

449
00:19:48,700 --> 00:19:51,580
Hivi sasa, karibu kila mpango
umefanya imeandikwa ni wasiokuwa na utaifa.

450
00:19:51,580 --> 00:19:53,334
Mara tu ni kosa kukimbia, hiyo ni yake.

451
00:19:53,334 --> 00:19:55,000
Hakuna kumbukumbu au kumbukumbu yake.

452
00:19:55,000 --> 00:19:56,110
Hakuna faili kuokolewa ni.

453
00:19:56,110 --> 00:19:58,120
Lakini kama huna wanataka
kuokoa pembejeo ambayo ina

454
00:19:58,120 --> 00:20:02,100
kilichotokea, kama katika mchezo au mpango
kama hii, ni zamu nje tunaweza kufanya hivyo.

455
00:20:02,100 --> 00:20:04,360
Na utaona hii zaidi
katika pset 4 na katika sehemu.

456
00:20:04,360 --> 00:20:08,661
Lakini mstari huu 23 kimsingi
inajenga faili inayoitwa students.csv.

457
00:20:08,661 --> 00:20:10,160
Na unaweza kuwa na kuonekana huu kabla.

458
00:20:10,160 --> 00:20:14,250
Hata kama wewe sijawahi alisoma CS kabla,
CSV ni koma vigezo.

459
00:20:14,250 --> 00:20:19,000
Ni kama mtu maskini sana ya
toleo la Excel file,

460
00:20:19,000 --> 00:20:22,270
ambayo ina maana kwamba inaweza kufunguliwa
katika Excel na katika Apple Hesabu,

461
00:20:22,270 --> 00:20:23,830
na ina safu na nguzo.

462
00:20:23,830 --> 00:20:26,485
Lakini siyo wamiliki
muundo kama Microsoft au Apple.

463
00:20:26,485 --> 00:20:29,840
Ni koma tu kutenganisha
maadili ambayo tutaweza kuona katika wakati huu.

464
00:20:29,840 --> 00:20:31,010
>> Na tu kuchukua nadhani.

465
00:20:31,010 --> 00:20:33,480
Katika mstari 23, katika sana
Mwishoni, hoja ya pili yangu

466
00:20:33,480 --> 00:20:37,700
kwa kazi hii mpya iitwayo
f wazi kwa ajili ya faili wazi ni w.

467
00:20:37,700 --> 00:20:39,430
Nini kinaweza kuashiria w?

468
00:20:39,430 --> 00:20:40,022
Yeah?

469
00:20:40,022 --> 00:20:41,260
>> Watazamaji: Ni inakuwezesha kuandika na faili?

470
00:20:41,260 --> 00:20:42,630
>> DAVID J. Malan: Ni inakuwezesha
kuandika na faili.

471
00:20:42,630 --> 00:20:44,810
Hivyo kuna michache ya variants
tuweze kuziba katika hapa.

472
00:20:44,810 --> 00:20:47,184
Lakini kama wewe tu unataka kusoma
file, kwamba ni kuangalia ni

473
00:20:47,184 --> 00:20:50,010
na kusoma katika kumbukumbu, wewe
tu kutumia quote unquote "r".

474
00:20:50,010 --> 00:20:53,110
Kama unataka kuandika kwa
file, matumizi quote unquote "w".

475
00:20:53,110 --> 00:20:55,190
Kuna pia append na
michache ya mambo mengine

476
00:20:55,190 --> 00:20:57,356
kama unataka kurekebisha files zilizopo.

477
00:20:57,356 --> 00:21:00,480
Sasa tunakwenda kuweka kuona hii
Jambo, basi tutaweza kurudi kwa kujipanga 24.

478
00:21:00,480 --> 00:21:02,640
NULL, ni zamu nje, ni
thamani maalum kwamba

479
00:21:02,640 --> 00:21:06,070
inaweza kurudishwa na baadhi ya kazi
kama kitu amekwenda wrong--

480
00:21:06,070 --> 00:21:08,490
kama faili haipo,
kama umefanya kukimbia nje ya kumbukumbu,

481
00:21:08,490 --> 00:21:09,620
au kundi la makosa mengine.

482
00:21:09,620 --> 00:21:13,470
Lakini kwa sasa, hebu tu kudhani kwamba hii
ni tu ya kawaida ya kuangalia makosa.

483
00:21:13,470 --> 00:21:17,090
Hapa katika mstari 26, mimi nina iterating
0-3 juu ya wanafunzi yangu yote.

484
00:21:17,090 --> 00:21:20,470
Na hii ni aina ya aina
ya kazi mpya, fprintf,

485
00:21:20,470 --> 00:21:21,460
lakini tu kuchukua nadhani.

486
00:21:21,460 --> 00:21:24,370
Kama printf ni magazeti
kamba mpangilio

487
00:21:24,370 --> 00:21:26,507
je fprintf pengine ina maana gani?

488
00:21:26,507 --> 00:21:27,590
Watazamaji: Magazeti na faili.

489
00:21:27,590 --> 00:21:29,290
DAVID J. Malan: Magazeti a
mpangilio kamba na faili.

490
00:21:29,290 --> 00:21:31,180
Hilo ndilo ziada
f njia ni faili.

491
00:21:31,180 --> 00:21:36,420
Na mpya hoja ya kwanza ina kuwa
kutofautiana kwamba inawakilisha faili yako.

492
00:21:36,420 --> 00:21:38,866
Kisha sisi tu kuwa na muundo
kamba tu kama printf.

493
00:21:38,866 --> 00:21:40,740
Na hata kama hii
syntax ni mpya, hii tu

494
00:21:40,740 --> 00:21:44,610
ina maana kuziba katika jina mwanafunzi,
kuziba-katika mwanafunzi mabweni, na kisha

495
00:21:44,610 --> 00:21:47,160
na fclose, karibu faili.

496
00:21:47,160 --> 00:21:49,730
Na kisha lastly-- hii ni mpya
na tutaweza kurudi huu

497
00:21:49,730 --> 00:21:53,240
kabla long-- mimi nina kumkomboa
mwanafunzi kwa sababu za

498
00:21:53,240 --> 00:21:54,860
yaliyotokea juu juu huko.

499
00:21:54,860 --> 00:21:56,820
Lakini tutaweza kurudi
kwa kuwa kabla long--

500
00:21:56,820 --> 00:21:59,820
hiyo ni kwa sababu ya jinsi GetString ni
kweli kazi chini ya Hood.

501
00:21:59,820 --> 00:22:01,280
>> Basi hebu tuangalie kwa haraka hapa.

502
00:22:01,280 --> 00:22:04,380
Kama mimi aina ls katika orodha yangu,
taarifa kwamba mimi si

503
00:22:04,380 --> 00:22:09,360
na faili inayoitwa students.csv,
tu si kuna, haipo.

504
00:22:09,360 --> 00:22:14,965
Hivyo kama mimi sasa kukusanya mpango huu,
kufanya structs-1,. / structs-1,

505
00:22:14,965 --> 00:22:20,570
na mimi nina kwenda mbele na aina katika
Andi, ambaye anaishi katika Berkeley katika Yale.

506
00:22:20,570 --> 00:22:26,350
Tunakwenda kuwa na Rob ambaye
anaishi katika Thayer siku hizi.

507
00:22:26,350 --> 00:22:33,760
Na hebu kuja na ambapo
ni, nadhani, Maria ni katika Mather,

508
00:22:33,760 --> 00:22:35,100
kama mimi nimekumbuka usahihi.

509
00:22:35,100 --> 00:22:36,460
>> Hivyo kitu inaonekana kutokea.

510
00:22:36,460 --> 00:22:40,680
Lakini kama mimi aina ls sasa,
kuna students.csv.

511
00:22:40,680 --> 00:22:43,080
Hebu kwenda mbele na students.csv wazi.

512
00:22:43,080 --> 00:22:46,050
Hii ni mara ya pili sana
nyepesi faili.

513
00:22:46,050 --> 00:22:49,570
Lakini nimepata tu iliyopitishwa mkataba
kwamba nina safu mbili na nguzo hapa.

514
00:22:49,570 --> 00:22:52,020
Safu ya kwanza ni
watu wa kwanza wa majina.

515
00:22:52,020 --> 00:22:55,740
Safu ya pili ni mwanafunzi
Dorm, au chuo, au nyumba, au whatnot.

516
00:22:55,740 --> 00:22:57,900
Na sasa nimekuwa kuokolewa huu
kudumu katika faili.

517
00:22:57,900 --> 00:22:59,280
>> Hivyo si yote ya kuvutia.

518
00:22:59,280 --> 00:23:02,980
Lakini hii ni jiwe wanazidi sasa
na kuwa na uwezo wa kuendelea maelezo

519
00:23:02,980 --> 00:23:04,040
kudumu.

520
00:23:04,040 --> 00:23:08,340
Basi hebu angalia sasa yale zaidi tunaweza
kufanya na haya na mengine makala.

521
00:23:08,340 --> 00:23:10,729
Lakini kwanza, maswali yoyote?

522
00:23:10,729 --> 00:23:12,145
Hiyo ilikuwa ni mengi, na kwamba alikuwa haraka.

523
00:23:12,145 --> 00:23:16,131
Lakini utaona mengi
zaidi katika pset 4, pia.

524
00:23:16,131 --> 00:23:16,630
Yeah?

525
00:23:16,630 --> 00:23:19,360
>> Watazamaji: Je, kuna njia ya
kuendelea kuongeza majina ya faili hayo?

526
00:23:19,360 --> 00:23:19,880
>> DAVID J. Malan: swali nzuri.

527
00:23:19,880 --> 00:23:21,800
Je, kuna njia ya kuendelea
kuongeza majina ya faili hayo?

528
00:23:21,800 --> 00:23:22,340
Ndiyo.

529
00:23:22,340 --> 00:23:24,630
Na, kwa kweli, kama wewe kuishia
up re-kufungua faili,

530
00:23:24,630 --> 00:23:26,780
ungependa kutumia kunukuu
unquote "" kwa append,

531
00:23:26,780 --> 00:23:31,090
ambayo itakuwa tu kuongeza line mpya,
mstari mpya tena na tena, hasa.

532
00:23:31,090 --> 00:23:32,010
Nzuri swali.

533
00:23:32,010 --> 00:23:32,950
Maswali mengine?

534
00:23:32,950 --> 00:23:33,450
Yeah?

535
00:23:33,450 --> 00:23:35,580
Watazamaji: Kama mbio
Mpango tena hivi sasa,

536
00:23:35,580 --> 00:23:38,000
itakuwa ni kuendelea kuongeza majina kwa
faili au itakuwa ni kufungua faili mpya?

537
00:23:38,000 --> 00:23:38,740
>> DAVID J. Malan: Ah, nzuri swali.

538
00:23:38,740 --> 00:23:41,448
Kama mbio mpango tena haki
sasa, labda typed katika majina mapya,

539
00:23:41,448 --> 00:23:44,820
itakuwa ni kuongeza faili
au overwrite faili?

540
00:23:44,820 --> 00:23:47,420
Mwisho, kwa sababu mimi nina
si kwa kutumia hali ya append.

541
00:23:47,420 --> 00:23:49,930
Na kwa sababu mimi nina tu upofu
kufungua faili kwa ajili ya kuandika,

542
00:23:49,930 --> 00:23:51,310
ni tu kwenda overwrite faili.

543
00:23:51,310 --> 00:23:54,570
Hivyo napenda kweli unahitaji kufanya ni append,
kama nataka kweli kuwa kwa muda mrefu

544
00:23:54,570 --> 00:23:55,350
database.

545
00:23:55,350 --> 00:23:58,220
>> Sasa CSV ni muhimu, kusema ukweli, hata
kwa kama kama wewe ni writing--

546
00:23:58,220 --> 00:24:00,100
na tutaweza hatimaye kuona hii
baadaye katika muhula wakati

547
00:24:00,100 --> 00:24:01,455
tunatumia CSVs kwa madhumuni mengine.

548
00:24:01,455 --> 00:24:04,920
Kama unataka kuhifadhi wote wa watu
ambao wamejiandikisha kwa baadhi ya tukio hilo,

549
00:24:04,920 --> 00:24:07,420
au saini kwa ajili ya mwanafunzi wako
kundi, au kitu kama hicho,

550
00:24:07,420 --> 00:24:10,330
kuhifadhi data katika aina hii
ya muundo ni super rahisi.

551
00:24:10,330 --> 00:24:12,580
Kwa sababu halisi, kama mimi
walikuwa kupakua faili hii.

552
00:24:12,580 --> 00:24:14,540
Mimi naweza double-- na
hebu kweli kujaribu hii

553
00:24:14,540 --> 00:24:16,720
kama nina Excel au Hesabu hapa.

554
00:24:16,720 --> 00:24:19,130
>> Mimi nina kwenda haki-click
au kudhibiti-click faili yangu.

555
00:24:19,130 --> 00:24:20,020
Whoops.

556
00:24:20,020 --> 00:24:21,830
Right-click au kudhibiti-click faili yangu.

557
00:24:21,830 --> 00:24:24,960
Haya, panya yangu si kushirikiana.

558
00:24:24,960 --> 00:24:32,694
Download-- nitakacho
download mafaili yote hapa ili

559
00:24:32,694 --> 00:24:33,860
tu ili niweze kunyakua hii moja.

560
00:24:33,860 --> 00:24:37,850
Na hebu angalia kama hii kazi
students.csv-- mara ya kwanza

561
00:24:37,850 --> 00:24:39,310
Nimekuwa kuanzishwa.

562
00:24:39,310 --> 00:24:41,360
Sasa wanataka kuona mawasiliano yangu.

563
00:24:41,360 --> 00:24:44,310
Sasa, mimi haja ya kujiandikisha.

564
00:24:44,310 --> 00:24:47,620
Kuona jinsi gani ni rahisi kutumia CSVs?

565
00:24:47,620 --> 00:24:50,840
Ndiyo, kuitunza hadi sasa.

566
00:24:50,840 --> 00:24:52,375
Sawa, sasa tuko tayari kwa ajili ya darasa.

567
00:24:52,375 --> 00:24:58,750

568
00:24:58,750 --> 00:25:00,370
OK, loo, nini mpya?

569
00:25:00,370 --> 00:25:02,920
OK, karibu.

570
00:25:02,920 --> 00:25:04,750
Hiyo ilikuwa ni kichawi.

571
00:25:04,750 --> 00:25:07,280
Sawa, sasa tuna update.

572
00:25:07,280 --> 00:25:10,890
Na sasa, alisahau nini
faili Mimi awali kufunguliwa,

573
00:25:10,890 --> 00:25:13,090
lakini kile a-- kuna sisi kwenda.

574
00:25:13,090 --> 00:25:16,341
OK, hivyo kwa sasa tuna Excel file.

575
00:25:16,341 --> 00:25:18,290
Asante.

576
00:25:18,290 --> 00:25:20,764
>> OK, hivyo nini mimi ilikuwa ni sehemu rahisi.

577
00:25:20,764 --> 00:25:23,930
Bila shaka mimi naweza kuwa kabla ya imewekwa
Excel, au Hesabu, au chochote mpango.

578
00:25:23,930 --> 00:25:25,846
Lakini hii ni nzuri, kwa sababu
sasa siwezi kuendesha

579
00:25:25,846 --> 00:25:28,090
data katika muundo standard.

580
00:25:28,090 --> 00:25:30,294
>> Hivyo sasa hebu mazingira
kubadili ambapo sisi kushoto mbali

581
00:25:30,294 --> 00:25:32,710
Mara ya mwisho, ambayo ilikuwa kuanza
kuchukua mbali magurudumu mafunzo.

582
00:25:32,710 --> 00:25:34,543
Lakini kwanza, hakuwa
kuona hii mapema chakula cha mchana

583
00:25:34,543 --> 00:25:38,150
kwa mara nyingine tena kinachotokea hapa katika Moto na
Barafu katika Cambridge, Sitar katika New Haven.

584
00:25:38,150 --> 00:25:43,150
Ishara ya juu kwenye tovuti CS50s ASAP
kujiunga CS50 wanafunzi na wafanyakazi.

585
00:25:43,150 --> 00:25:46,090
>> Hivyo sisi alichukua magurudumu mafunzo
mbali juu ya Jumatatu kama follows--

586
00:25:46,090 --> 00:25:49,120
kamba imetangazwa katika
CS50s maktaba kwa muda fulani.

587
00:25:49,120 --> 00:25:52,650
Na ni nzuri, kwa sababu inaruhusu
sisi kuzungumzia vigezo kama kuwa

588
00:25:52,650 --> 00:25:54,660
Maneno kamili na hukumu na zaidi.

589
00:25:54,660 --> 00:25:56,710
Lakini zinageuka kamba haipo.

590
00:25:56,710 --> 00:26:00,200
Hiyo ni kisawe, au vinginevyo,
kwamba tuna umba kwa kitu ambacho

591
00:26:00,200 --> 00:26:03,780
kweli ni kidogo zaidi
kiufundi aitwaye * Char.

592
00:26:03,780 --> 00:26:07,900
>> Na hakika, tuliona mfano
wa mpango Jumatatu

593
00:26:07,900 --> 00:26:11,200
kwamba hakuwa na kuishi kabisa kama sisi ilivyotarajiwa.

594
00:26:11,200 --> 00:26:13,630
Hii ilikuwa ni faili, kulinganisha-0.

595
00:26:13,630 --> 00:26:17,910
Na kukumbuka kuwa kulinganisha-0, ikiwa
Mimi recompile mpango Jumatatu

596
00:26:17,910 --> 00:26:22,670
na kukimbia kulinganisha-0 na aina katika mama katika
lowercase, na mama katika lowercase tena.

597
00:26:22,670 --> 00:26:25,320
Mpango alisisitiza mimi
aina ya mambo mbalimbali,

598
00:26:25,320 --> 00:26:29,210
hata kama mama, yote katika
lowercase, ni sawa kuibua.

599
00:26:29,210 --> 00:26:31,990
Kwa hiyo kile ni jibu fupi
kwa nini kompyuta anadhani

600
00:26:31,990 --> 00:26:34,500
wale masharti mawili ni tofauti?

601
00:26:34,500 --> 00:26:35,250
Yeah?

602
00:26:35,250 --> 00:26:36,534
>> Watazamaji: [inaudible]

603
00:26:36,534 --> 00:26:37,450
DAVID J. Malan: Haki.

604
00:26:37,450 --> 00:26:39,600
Kwa hiyo, mama, mara ya kwanza
Mimi aina yake katika, ni kuwa

605
00:26:39,600 --> 00:26:42,710
kuhifadhiwa mahali fulani katika kompyuta yangu
kumbukumbu lakini katika eneo tofauti

606
00:26:42,710 --> 00:26:44,690
kuliko mara ya pili mimi aina katika mama.

607
00:26:44,690 --> 00:26:46,580
Sasa ni hakika inaweza kuwa optimized.

608
00:26:46,580 --> 00:26:49,205
Kompyuta inaweza kuwa smart na
kutambua masharti haya mawili, hey,

609
00:26:49,205 --> 00:26:49,954
wao uko kufanana.

610
00:26:49,954 --> 00:26:51,520
Basi mimi si redundantly kuhifadhi.

611
00:26:51,520 --> 00:26:54,229
Lakini kompyuta kufanya hivyo
optimization isipokuwa wewe kuwaambia.

612
00:26:54,229 --> 00:26:56,061
Hivyo, kwa default, wao uko
tu kwenda kuishia

613
00:26:56,061 --> 00:26:57,670
katika maeneo mawili tofauti katika kumbukumbu.

614
00:26:57,670 --> 00:27:01,570
Na hivyo kuwa zaidi ya wazi, wakati
sisi ikilinganishwa masharti mawili,

615
00:27:01,570 --> 00:27:03,950
kwanza aliitwa s,
pili aliitwa

616
00:27:03,950 --> 00:27:08,530
t, ni nini hasa ilikuwa ni mimi
kulinganisha hapa kwenye mstari 13?

617
00:27:08,530 --> 00:27:09,494
Naam.

618
00:27:09,494 --> 00:27:12,390
>> Watazamaji: Ni mahali katika kumbukumbu
kwamba kutofautiana uhakika na.

619
00:27:12,390 --> 00:27:14,900
>> DAVID J. Malan: Hasa, nilikuwa
kulinganisha nafasi katika kumbukumbu

620
00:27:14,900 --> 00:27:16,300
kwamba vigezo wale alisema kwa.

621
00:27:16,300 --> 00:27:20,560
Hivyo hasa, ikiwa mama alikuwa katika
Byte namba 1, na 2, na 3,

622
00:27:20,560 --> 00:27:24,020
na 4-- kwa sababu kumbuka backslash
0 haja ya kuwa na njia yote mwishoni.

623
00:27:24,020 --> 00:27:29,420
Na mfano wa pili wa mama, m-o-m,
Ilikuwa kwa anwani ya 10, 11, 12, na 13.

624
00:27:29,420 --> 00:27:33,100
Mimi nilikuwa kulinganisha 1, anwani hiyo,
kwamba eneo katika kumbukumbu,

625
00:27:33,100 --> 00:27:35,160
dhidi ya 10, ambayo ni
wazi si sawa.

626
00:27:35,160 --> 00:27:36,260
1 ni si 10.

627
00:27:36,260 --> 00:27:39,620
>> Hivyo hii ni nzuri kwa kuwa
ni pretty moja kwa moja.

628
00:27:39,620 --> 00:27:42,870
Lakini ni tatizo kadiri
hatuwezi wanaonekana kulinganisha masharti.

629
00:27:42,870 --> 00:27:44,930
Hivyo fundamentally--
na katika ngazi hii ya chini,

630
00:27:44,930 --> 00:27:47,300
kama alitaka kutekeleza
mpango wa kulinganisha

631
00:27:47,300 --> 00:27:50,270
maneno mawili tofauti kwamba
mtumiaji typed katika kwa ubora,

632
00:27:50,270 --> 00:27:53,944
je, wao kujipanga char kwa
Char, tu katika ujumla,

633
00:27:53,944 --> 00:27:55,360
tunahitaji nini cha kufanya, inaonekana?

634
00:27:55,360 --> 00:27:57,940
Siyo kutosha tu
kuangalia wale anwani miwili.

635
00:27:57,940 --> 00:27:58,860
Tufanye nini haja ya kufanya?

636
00:27:58,860 --> 00:27:59,360
Yeah?

637
00:27:59,360 --> 00:28:01,120
>> Watazamaji: Iterate kupitia
kamba [inaudible].

638
00:28:01,120 --> 00:28:02,600
>> DAVID J. Malan: Yeah, hebu
iterate kupitia kamba.

639
00:28:02,600 --> 00:28:05,808
Hebu kutumia kwa kitanzi, kitanzi wakati, au
chochote wewe ni vizuri zaidi kwa.

640
00:28:05,808 --> 00:28:08,840
Na kama sisi tumepewa masharti mawili mahali fulani
katika kumbukumbu, hebu tuangalie kila ya

641
00:28:08,840 --> 00:28:11,770
tabia ya kwanza, basi kila ni wa pili
tabia, kisha ya tatu, na nne,

642
00:28:11,770 --> 00:28:15,206
na tano, mpaka sisi hit
nini thamani maalum mwangalizi?

643
00:28:15,206 --> 00:28:16,080
Watazamaji: [inaudible]

644
00:28:16,080 --> 00:28:18,800
DAVID J. Malan: Yeah, backslash
sifuri, ambapo kiwango katika ama kamba

645
00:28:18,800 --> 00:28:20,100
tunaweza kuamua hiyo ni yake.

646
00:28:20,100 --> 00:28:21,970
Je, sisi kuendana kila tabia moja?

647
00:28:21,970 --> 00:28:22,990
Kama siyo, kurudi uongo.

648
00:28:22,990 --> 00:28:24,770
Kama ni hivyo, kurudi kweli.

649
00:28:24,770 --> 00:28:28,800
Na hivyo hiyo ni nini hasa toleo hili
wa mpango kulinganisha-1.c gani.

650
00:28:28,800 --> 00:28:31,677
Ni sawa na kile sisi
inaonekana katika Jumatatu ila kwa kuwa nimekuwa

651
00:28:31,677 --> 00:28:34,760
wamezipata kuondoa neno kamba ingawa
kwamba hana impact-- kazi zote

652
00:28:34,760 --> 00:28:37,450
Mimi nina kufanya sasa ni kuondoa
baadhi ya mafunzo magurudumu Visual,

653
00:28:37,450 --> 00:28:40,880
lakini kuona wazi kwamba
s na t ni anwani.

654
00:28:40,880 --> 00:28:43,020
Na kwamba ni nini nyota,
kinyota, inawakilisha

655
00:28:43,020 --> 00:28:46,690
ni ya mitaani, inayojulikana
kitaalam zaidi kama pointer.

656
00:28:46,690 --> 00:28:49,880
>> Hivyo wakati mimi kutangaza s juu ya
mstari wa 9 na kusema Char * s,

657
00:28:49,880 --> 00:28:52,160
hiyo haina maana nipe kamba.

658
00:28:52,160 --> 00:28:56,360
Hiyo ina maana nipe kutofautiana ambao
lengo katika maisha ni kuhifadhi mahali.

659
00:28:56,360 --> 00:29:00,400
Kwa sababu mimi ni juu ya kuweka
pepe ya kamba ndani yake.

660
00:29:00,400 --> 00:29:03,500
Na hakika, GetString, kwa kuwa
wazi, haina kurudi kamba.

661
00:29:03,500 --> 00:29:06,110
Ni haina kurudi mama
backslash sifuri, per se.

662
00:29:06,110 --> 00:29:10,005
Je GetString mahsusi
na usahihi kurudi?

663
00:29:10,005 --> 00:29:10,880
Watazamaji: [inaudible]

664
00:29:10,880 --> 00:29:14,080
DAVID J. Malan: mitaani,
pepe ya tabia ya kwanza

665
00:29:14,080 --> 00:29:16,070
katika baadhi kamba ni imenipatia.

666
00:29:16,070 --> 00:29:19,250
Na hivyo sasa sisi ni kuona
keyword maalum tena.

667
00:29:19,250 --> 00:29:20,640
Na, mimi alluded hili mapema.

668
00:29:20,640 --> 00:29:23,620
Hii ni kwenda kuwa mkataba mzuri
kwamba tutaweza kuona tena na tena sasa.

669
00:29:23,620 --> 00:29:27,540
Mimi nina kuangalia ili kuhakikisha kuwa
s si batili na t sio null.

670
00:29:27,540 --> 00:29:30,100
Kwa sababu kulingana na yangu kweli
kutaja haraka awali,

671
00:29:30,100 --> 00:29:35,510
nini kinaweza maana ikiwa GetString anarudi si
anuani lakini N-U-L-L, ambayo ni mara ya pili,

672
00:29:35,510 --> 00:29:36,990
baadhi thamani maalum?

673
00:29:36,990 --> 00:29:37,890
>> Watazamaji: Kosa.

674
00:29:37,890 --> 00:29:38,600
>> DAVID J. Malan: Ni kosa.

675
00:29:38,600 --> 00:29:39,550
Kitu potoka.

676
00:29:39,550 --> 00:29:41,341
Na nini kawaida
kinaweza kutokea, hasa

677
00:29:41,341 --> 00:29:45,162
na strings-- ambayo inaweza kuwa
ya urefu haijulikani katika advance--

678
00:29:45,162 --> 00:29:46,870
labda kompyuta '
nje ya kumbukumbu, labda

679
00:29:46,870 --> 00:29:49,280
uliyochapa katika hizo a
muda mrefu neno au sentensi

680
00:29:49,280 --> 00:29:51,880
au pasted kama insha mkubwa
kuna tu si kumbukumbu ya kutosha.

681
00:29:51,880 --> 00:29:55,340
Na hivyo GetString hawezi kurudi
pepe ya jambo zima,

682
00:29:55,340 --> 00:29:56,620
hivyo ni tu anarudi kitu.

683
00:29:56,620 --> 00:30:00,580
Na inasema makosa yaliyotokea
na kurudi thamani maalum null.

684
00:30:00,580 --> 00:30:02,890
Ni anuani sifuri, hivyo kusema.

685
00:30:02,890 --> 00:30:06,157
>> Sasa ni zamu nje C kuja na
kazi ambayo hufanya hivyo iteration.

686
00:30:06,157 --> 00:30:09,240
Hatuna kutekeleza hili kwa
a kwa kitanzi au kitanzi wakati sisi wenyewe.

687
00:30:09,240 --> 00:30:11,150
Tunaweza kutumia kazi,
aitwaye ufupi,

688
00:30:11,150 --> 00:30:15,400
koroga dira, au kamba kulinganisha, ambaye
lengo katika maisha ni kufanya hasa kwamba.

689
00:30:15,400 --> 00:30:19,990
Wewe kuwapa kuyatumia mbili, anwani miwili,
na itakuwa kwenda wale anwani

690
00:30:19,990 --> 00:30:23,130
na kisha kulinganisha barua kwa
barua kwa barua kwa ubora,

691
00:30:23,130 --> 00:30:26,610
kuacha tu wakati mambo ni kweli?

692
00:30:26,610 --> 00:30:31,540
Wakati shirikishi lazima koroga dira
kuacha iterating, tu kuwa wazi?

693
00:30:31,540 --> 00:30:35,400
Wakati hits backslash 0 katika ama
kamba, ambapo kiwango inaweza kuamua

694
00:30:35,400 --> 00:30:38,910
ina kila kitu kuendana, au
kumekuwa iliyopo?

695
00:30:38,910 --> 00:30:42,740
>> Hivyo, kama sisi kukimbia hii sasa na kujaribu
yetu mtaji mchezo kidogo,

696
00:30:42,740 --> 00:30:49,260
hivyo kufanya kulinganisha-1, ./compare-1, na
aina mama katika lowercase mara zote mbili.

697
00:30:49,260 --> 00:30:50,560
Sasa ni kitu kimoja.

698
00:30:50,560 --> 00:30:54,080
Na kama mimi kufanya hivyo tena na
lowercase na kisha labda herufi kubwa.

699
00:30:54,080 --> 00:30:56,720
Sasa ni kweli tofauti
kati ya juu na ndogo.

700
00:30:56,720 --> 00:31:00,440
Hivyo si yote ngumu au
kichawi, lakini haina sasa kueleza

701
00:31:00,440 --> 00:31:03,140
nini kinaendelea chini ya Hood.

702
00:31:03,140 --> 00:31:07,640
>> Kwa hiyo kile zaidi tunaweza kutafuta
kutokana na aina hii ya somo?

703
00:31:07,640 --> 00:31:08,980
Basi hebu tuangalie hii.

704
00:31:08,980 --> 00:31:15,380
Mimi nina kwenda mbele na kuandika
Mpango wa haraka hapa inaitwa nakala-0.

705
00:31:15,380 --> 00:31:21,594
Na sasa hebu kwenda mbele na kwa kweli
hebu kufanya Haya na nakala-0,

706
00:31:21,594 --> 00:31:23,010
kuangalia nini mimi nimepata hapa.

707
00:31:23,010 --> 00:31:24,712
Mimi kwanza kuwaambia mtumiaji, kusema kitu.

708
00:31:24,712 --> 00:31:26,420
Kisha mimi kupata kamba
na mimi kuhifadhiwa katika s.

709
00:31:26,420 --> 00:31:29,810
Kisha mimi kuangalia kama s ni sawa
sawa NULL, tu kurudi 1.

710
00:31:29,810 --> 00:31:31,590
Hivyo hii ni tu kiwango kuangalia makosa.

711
00:31:31,590 --> 00:31:33,112
Hakuna kitu ya kuvutia kilichotokea.

712
00:31:33,112 --> 00:31:36,320
Na kwa kweli, kama sisi kujikwamua makosa
cheki, hii inaonekana kama wiki 1 kificho

713
00:31:36,320 --> 00:31:36,985
kwa sasa.

714
00:31:36,985 --> 00:31:39,110
Lakini nimeanza kupata
vizuri kidogo juu ya hilo.

715
00:31:39,110 --> 00:31:43,340
>> Sasa katika mstari 16, wiki iliyopita, labda
siku hata wanandoa au dakika iliyopita,

716
00:31:43,340 --> 00:31:46,720
unaweza kusema mstari 16 ni
kujenga variable kuitwa t

717
00:31:46,720 --> 00:31:48,219
na kuiga s ndani yake.

718
00:31:48,219 --> 00:31:50,010
Na hiyo ndiyo kikamilifu
busara takeaway.

719
00:31:50,010 --> 00:31:51,560
Lakini kuwa sahihi zaidi sasa.

720
00:31:51,560 --> 00:31:54,190
Kile kinachotokea katika mstari 16?

721
00:31:54,190 --> 00:31:56,170
Nini ni kupata kunakiliwa
kutoka kulia kwenda kushoto?

722
00:31:56,170 --> 00:31:56,669
Yeah?

723
00:31:56,669 --> 00:31:58,490
Watazamaji: Je t kupata pepe ya s?

724
00:31:58,490 --> 00:32:01,220
>> DAVID J. Malan: Hasa, t
ni kupata pepe ya s.

725
00:32:01,220 --> 00:32:05,170
Hivyo kuwa wazi sasa, kama mimi kwenda
nyuma ya mfano kwamba mapema

726
00:32:05,170 --> 00:32:08,520
na mimi kuteka kitu nimekuwa typed katika.

727
00:32:08,520 --> 00:32:11,640
Na nini nimekuwa typed
in-- hapa ni s, na hapa

728
00:32:11,640 --> 00:32:15,830
ni nini nimekuwa typed katika mahali fulani katika
kumbukumbu, mama na kisha backslash

729
00:32:15,830 --> 00:32:17,840
0 hiyo aliongeza kwa ajili yangu.

730
00:32:17,840 --> 00:32:23,060
What I kuhifadhiwa katika hapa, kukumbuka,
hii ni katika eneo 1, 2, 3, 4,

731
00:32:23,060 --> 00:32:24,655
hii ni nini sasa katika s.

732
00:32:24,655 --> 00:32:29,220
Hivyo kama kwenye mstari 16, nasema nipe
mwingine kutofautiana kuitwa t na kuhifadhi

733
00:32:29,220 --> 00:32:33,590
katika katika thamani ya s, nini
anapata kuhifadhiwa hapa si mama

734
00:32:33,590 --> 00:32:35,480
bali tu namba 1.

735
00:32:35,480 --> 00:32:38,520
>> Hivyo kama sisi kuangalia mbele katika mpango huu
sasa, nini kitatokea?

736
00:32:38,520 --> 00:32:40,690
Hivyo taarifa kwamba kuna
kazi hii waweza

737
00:32:40,690 --> 00:32:44,410
wametumia huu baadhi ya wakati uliopita kwa Kaisari,
au Vigenere, au labda si wakati wote.

738
00:32:44,410 --> 00:32:48,170
Mimi kudai kwa printf yangu, mimi nina
kwenda capitalize nakala t.

739
00:32:48,170 --> 00:32:51,616
Kwanza katika mstari 19, haraka sanity
kuangalia, hundi strlen urefu wa t.

740
00:32:51,616 --> 00:32:53,740
Kwa sababu mimi sitaki
kujaribu capitalize kitu

741
00:32:53,740 --> 00:32:55,104
kama hakuna kamba huko.

742
00:32:55,104 --> 00:32:57,520
Kama mtumiaji tu hit Enter,
kuna kitu capitalize.

743
00:32:57,520 --> 00:33:01,100
Hivyo Sitaki kufanya mstari 21.

744
00:33:01,100 --> 00:33:05,758
Hivyo mstari 21 ni kuyafanyia
ambayo barua, inaonekana, katika t?

745
00:33:05,758 --> 00:33:06,514
>> Watazamaji: m?

746
00:33:06,514 --> 00:33:08,722
DAVID J. Malan: Inaonekana
kama ni kuiga ambayo moja?

747
00:33:08,722 --> 00:33:09,486
Watazamaji: m.

748
00:33:09,486 --> 00:33:10,450
DAVID J. Malan: Uh, m.

749
00:33:10,450 --> 00:33:12,685
OK, hivyo m kwanza,
kwa sababu taarifa kwamba mimi nina

750
00:33:12,685 --> 00:33:14,935
kupita kwa toupper, ambayo
kama wewe sijawahi kuiona ni

751
00:33:14,935 --> 00:33:16,980
tu kazi kwa
capitalize kama mchango wake.

752
00:33:16,980 --> 00:33:20,240
t mabano sifuri ina maana kutoa
mimi tabia sifuri ya t.

753
00:33:20,240 --> 00:33:22,550
Na hivyo ni jinsi gani hii
picha mabadiliko, kuwa wazi?

754
00:33:22,550 --> 00:33:25,490

755
00:33:25,490 --> 00:33:29,160
Kinachotakiwa kupata kuandikwa upya au kubadilishwa
kwa heshima na s na t na mama

756
00:33:29,160 --> 00:33:30,097
backslash sifuri.

757
00:33:30,097 --> 00:33:31,470
>> Watazamaji: [inaudible]

758
00:33:31,470 --> 00:33:34,030
>> DAVID J. Malan: Yeah,
hivyo hii moja hapa tu

759
00:33:34,030 --> 00:33:40,860
mahitaji ya kupata iliyopita to-- kurekebisha Haya
mahitaji ya kupata iliyopita katika mji mkuu wa m.

760
00:33:40,860 --> 00:33:44,330
Lakini sasa, angalia baadaye katika
mpango, kama mimi magazeti nje

761
00:33:44,330 --> 00:33:49,800
s na t kama mimi safi hapa, kuangalia nini
kinaenda kutokea uchapishaji nje s na t.

762
00:33:49,800 --> 00:33:54,310
Hivyo kufanya nakala-0, ./copy-0.

763
00:33:54,310 --> 00:33:57,140
Hebu kwenda mbele na aina
katika mama katika lowercase wote.

764
00:33:57,140 --> 00:34:00,140
Taarifa zote mbili awali na
nakala wamekuwa mtaji.

765
00:34:00,140 --> 00:34:00,850
Kwa nini?

766
00:34:00,850 --> 00:34:04,431
Naam, s na t ni wawili akizungumzia,
kama wewe, chunk kama hicho cha kumbukumbu.

767
00:34:04,431 --> 00:34:06,930
Na kusema ukweli, hii ni kupata
kweli uninteresting-- ukweli

768
00:34:06,930 --> 00:34:09,150
kwamba sisi ni kutumia anwani sifuri hapa.

769
00:34:09,150 --> 00:34:11,719
I mean, mimi si kweli huduma
ambapo mambo ni katika kumbukumbu.

770
00:34:11,719 --> 00:34:13,550
Pole mimi nina kufutwa kidogo sana.

771
00:34:13,550 --> 00:34:15,674
Lakini mimi si kweli huduma
ambapo mambo ni katika kumbukumbu.

772
00:34:15,674 --> 00:34:18,510
Na hivyo, kwa kweli kile
programmers huwa na kufikiri kuhusu

773
00:34:18,510 --> 00:34:21,080
ni kwamba wakati majadiliano juu ya
pepe, au pointer,

774
00:34:21,080 --> 00:34:22,679
anayejali ambapo ni katika kumbukumbu.

775
00:34:22,679 --> 00:34:24,989
Sijali kama ni katika
Byte moja au bilioni moja.

776
00:34:24,989 --> 00:34:27,920
I just huduma ya kwamba hii
kutofautiana ni ufanisi

777
00:34:27,920 --> 00:34:29,620
akionyesha kwamba chunk ya kumbukumbu.

778
00:34:29,620 --> 00:34:33,350
Na hivyo, tangu sasa, badala ya quibble
zaidi ya anwani kumbukumbu holela, hebu

779
00:34:33,350 --> 00:34:36,710
kuanza tu kuteka kuyatumia
kama kuyatumia, kama mishale.

780
00:34:36,710 --> 00:34:39,340
Kwa hiyo kile s na t kweli ni,
kwa mujibu wa mpango huu,

781
00:34:39,340 --> 00:34:42,130
kwa sababu ya jinsi mimi umba t,
ni vigezo mbili tu tofauti

782
00:34:42,130 --> 00:34:43,840
akionyesha chunk kama hicho cha kumbukumbu.

783
00:34:43,840 --> 00:34:45,215
Na sisi hawajali walipo.

784
00:34:45,215 --> 00:34:47,130
Hivyo tunaweza abstract mbali undani huo.

785
00:34:47,130 --> 00:34:48,780
>> Hivyo ni jinsi gani mimi kurekebisha hili?

786
00:34:48,780 --> 00:34:54,120
Kama nataka kuandika toleo la nakala
mpango huo kwa kweli nakala kamba

787
00:34:54,120 --> 00:34:56,840
na herufi tu
nakala, tu intuitively,

788
00:34:56,840 --> 00:34:59,766
nini got kuwa
kingo kwa ufumbuzi wetu?

789
00:34:59,766 --> 00:35:00,640
Watazamaji: [inaudible]

790
00:35:00,640 --> 00:35:01,420
DAVID J. Malan: Tunahitaji nini?

791
00:35:01,420 --> 00:35:01,820
Watazamaji: Chunk ya kumbukumbu.

792
00:35:01,820 --> 00:35:03,280
DAVID J. Malan: Tunahitaji
mwingine chunk ya kumbukumbu, sawa?

793
00:35:03,280 --> 00:35:05,360
Hatujui jinsi ya
kufanya hivyo bado, lazima.

794
00:35:05,360 --> 00:35:11,330
Lakini mimi aina ya haja hili kutokea hivyo
kwamba mama awali katika kesi ya chini

795
00:35:11,330 --> 00:35:14,170
mwisho juu katika kwamba chunk ya ziada ya kumbukumbu.

796
00:35:14,170 --> 00:35:19,770
Na kisha wakati mimi kubadili nakala, mimi
hawataki mabadiliko nakala hii hapa.

797
00:35:19,770 --> 00:35:26,020
Mimi badala wanataka kubadili tu hii
nakala ili awali ni kubadilika.

798
00:35:26,020 --> 00:35:27,980
>> Kwa hiyo, hebu angalia jinsi sisi tupate kufanya hivyo.

799
00:35:27,980 --> 00:35:31,800
Katika nakala-1, ambayo tayari
wamekuwa kuvuliwa maoni,

800
00:35:31,800 --> 00:35:33,250
lakini ni maoni online.

801
00:35:33,250 --> 00:35:36,710
Sisi badala kufanya following-- hizi
mistari ni sawa, kupata nami kamba

802
00:35:36,710 --> 00:35:38,340
na kuiita s.

803
00:35:38,340 --> 00:35:43,500
Lakini sasa hebu tuangalie moja ya yetu
tata lakini mwisho wa utata

804
00:35:43,500 --> 00:35:47,340
kwa muda, mstari 16 gani hasa huu.

805
00:35:47,340 --> 00:35:49,400
Hivyo kama comfy yako na
picha sisi tu drew--

806
00:35:49,400 --> 00:35:51,790
nipe chunk mpya ya kumbukumbu,
nakala kila kitu ndani yake,

807
00:35:51,790 --> 00:35:53,730
hebu angalia jinsi sisi kutafsiri kwamba kwa kificho.

808
00:35:53,730 --> 00:35:59,400
>> Hivyo mstari 16, upande wa kushoto,
char * t anitiaye sanduku hii zaidi ya hapa.

809
00:35:59,400 --> 00:36:00,230
Hayo ni yote ni gani.

810
00:36:00,230 --> 00:36:03,240
Upande wa kulia,
m alloc, au malloc,

811
00:36:03,240 --> 00:36:06,480
ni kumbukumbu mgao, super dhana tu,
njia cryptic ya kusema tu

812
00:36:06,480 --> 00:36:07,640
nipe chunk ya kumbukumbu.

813
00:36:07,640 --> 00:36:09,290
Kiasi gani kumbukumbu tunahitaji?

814
00:36:09,290 --> 00:36:10,910
Naam, ni aina ya usemi mkubwa.

815
00:36:10,910 --> 00:36:12,570
Lakini hebu angalia nini anasema hapa.

816
00:36:12,570 --> 00:36:15,940
Hivyo hii, bila shaka, ni kutoa
mimi kamba urefu wa s.

817
00:36:15,940 --> 00:36:19,094
Kwa hiyo, mama ni lazima kuwa nini?

818
00:36:19,094 --> 00:36:21,010
Hivyo mitatu tu, sawa?
mama ni herufi tatu.

819
00:36:21,010 --> 00:36:22,830
Huwezi kuhesabu
sifuri backslash wakati

820
00:36:22,830 --> 00:36:25,960
majadiliano juu ya urefu wa kamba ni
kweli binadamu inayoonekana barua.

821
00:36:25,960 --> 00:36:28,020
Hivyo mama, hivyo hii inatoa mimi 3.

822
00:36:28,020 --> 00:36:31,170
Lakini kusubiri dakika, mimi nina sasa akiongeza 1.

823
00:36:31,170 --> 00:36:34,861
Kwa nini mimi kweli wanataka
kutenga 4 ka na si tu 3?

824
00:36:34,861 --> 00:36:35,360
Yeah?

825
00:36:35,360 --> 00:36:36,910
>> Watazamaji: Kwa thamani mwangalizi?

826
00:36:36,910 --> 00:36:38,951
>> DAVID J. Malan: Hasa,
kwa kuwa thamani mwangalizi.

827
00:36:38,951 --> 00:36:40,840
Kwa backslash sifuri,
Mimi haja 4 ka jumla.

828
00:36:40,840 --> 00:36:42,870
Kwa hiyo mimi haja urefu
ya kamba pamoja na 1.

829
00:36:42,870 --> 00:36:45,400
Na kisha tu kwa measure-- nzuri
hata kama juu ya mfumo huu,

830
00:36:45,400 --> 00:36:49,390
ni daima itakuwa 1-- mimi kusema
kuzidisha hili kwa ukubwa wa Char.

831
00:36:49,390 --> 00:36:51,552
Zamu nje sizeof ni
operator katika C kwamba

832
00:36:51,552 --> 00:36:53,260
tu atakwambia
idadi ya ka hiyo ni

833
00:36:53,260 --> 00:36:54,700
inahitajika kwa ajili ya aina fulani data.

834
00:36:54,700 --> 00:36:57,740
Haifanyi kazi kwa arrays,
kawaida, wakati mwingine ni gani.

835
00:36:57,740 --> 00:36:59,210
Lakini katika kesi ujumla, hakuna.

836
00:36:59,210 --> 00:37:02,330
Lakini itakuwa kuniambia jinsi wengi ka
char ni, ambayo zamu nje daima 1.

837
00:37:02,330 --> 00:37:04,080
Hivyo hii ni kama kuzidisha na 1.

838
00:37:04,080 --> 00:37:05,900
>> Hivyo super cryptic kuangalia mstari wa kanuni.

839
00:37:05,900 --> 00:37:09,320
Lakini wote ni gani ni anatoa
mimi chunk ya kumbukumbu.

840
00:37:09,320 --> 00:37:13,590
Lakini je, ni wanaonekana kuwa kuiga
chochote katika kumbukumbu?

841
00:37:13,590 --> 00:37:14,560
Bado.

842
00:37:14,560 --> 00:37:22,040
Na hivyo kile mimi kwenye mstari 22, na
23, 24, 25, vizuri, mimi tu kufanya hivyo.

843
00:37:22,040 --> 00:37:23,760
Na hii ni aina ya
umri wa mambo shule sasa.

844
00:37:23,760 --> 00:37:26,010
Hii ni kama pset 2, ambapo
wewe ni kusonga tu mambo

845
00:37:26,010 --> 00:37:28,620
kuzunguka katika kumbukumbu, au tuseme katika masharti.

846
00:37:28,620 --> 00:37:31,920
>> Hivyo mimi nina iterating kutoka 0 kwa
urefu wa kamba s.

847
00:37:31,920 --> 00:37:37,820
Na mimi nina kuiga tabia i-th
katika s katika i-th tabia katika t.

848
00:37:37,820 --> 00:37:41,820
Na kwa sababu mimi, programu, alifanya
uhakika na kutenga ka hasa kama wengi

849
00:37:41,820 --> 00:37:44,600
kama nahitaji, ni kamili
moja kwa moja uhusiano.

850
00:37:44,600 --> 00:37:47,060
Na mimi nakala mama katika
Herufi za chini kwa mwezi mmoja.

851
00:37:47,060 --> 00:37:50,170
Na kisha mwisho, mimi kufanya mstari huu.

852
00:37:50,170 --> 00:37:54,637
Na hivyo athari ni tu
capitalize t hii hapa.

853
00:37:54,637 --> 00:37:56,470
Hivyo mengi ya kunyonya, lakini
kama wewe tu kufikiria

854
00:37:56,470 --> 00:37:58,220
nini kweli kinachoendelea
chini ya Hood

855
00:37:58,220 --> 00:38:00,880
ni kusonga tu hizi
ka kote, yote

856
00:38:00,880 --> 00:38:06,617
inahitajika ili kutatua tatizo hili ni
tu kutupa hii chunk ya kumbukumbu.

857
00:38:06,617 --> 00:38:08,450
Sasa katika hatari ya
balaa, napenda kuonyesha

858
00:38:08,450 --> 00:38:13,200
mfano mmoja mwingine hiyo ni karibu
kufanana, isipokuwa kwa hii moja

859
00:38:13,200 --> 00:38:14,350
mstari wa kanuni.

860
00:38:14,350 --> 00:38:18,870
Hivyo hii ni hacker toleo la
ya mpango huu, kama wewe.

861
00:38:18,870 --> 00:38:21,050
Lakini hebu tu distill
ndani nini kinaendelea.

862
00:38:21,050 --> 00:38:28,920
Mstari 24 kutumika kwa kuwa t hii
mabano i anapata s mabano i.

863
00:38:28,920 --> 00:38:33,370
Sasa, mimi nina kubadilisha hii kwa
mengi zaidi cryptic nyota t

864
00:38:33,370 --> 00:38:36,280
pamoja na 1 ni sawa na nyota s pamoja na 1.

865
00:38:36,280 --> 00:38:38,702
>> Hivyo nini kinatokea na kwa nini
tuna tabia nyota?

866
00:38:38,702 --> 00:38:41,410
Tumeona nyota kabla, na
ni kuwa kutumika kwa njia tofauti hapa.

867
00:38:41,410 --> 00:38:45,490
Sisi hapo awali aliona * Char, sasa mimi nina kuona
a nyota mwanzoni, na hiyo ni sawa.

868
00:38:45,490 --> 00:38:48,190
Kwa sababu ni zamu nje sisi
unaweza aina ya infer tu

869
00:38:48,190 --> 00:38:50,280
kutoka kwa wale kwanza
kanuni nini kinaendelea.

870
00:38:50,280 --> 00:38:53,860
Hivyo tu kuwa wazi, ni nini s?

871
00:38:53,860 --> 00:38:55,052
Wiki iliyopita, ilikuwa kamba.

872
00:38:55,052 --> 00:38:56,260
Hiyo haina inatosha tena.

873
00:38:56,260 --> 00:38:57,690
S ni kitu gani, hasa?

874
00:38:57,690 --> 00:38:58,590
>> Watazamaji: [inaudible]

875
00:38:58,590 --> 00:38:59,881
>> DAVID J. Malan: Ni pointer.

876
00:38:59,881 --> 00:39:02,610
Ni pepe ya
tabia ya kwanza sisi typed katika.

877
00:39:02,610 --> 00:39:04,780
OK, ni nini t?

878
00:39:04,780 --> 00:39:05,660
>> Watazamaji: [inaudible]

879
00:39:05,660 --> 00:39:07,950
>> DAVID J. Malan:
anuani ya Byte kwanza

880
00:39:07,950 --> 00:39:10,490
katika t, kwamba chunk ya kumbukumbu reallocated.

881
00:39:10,490 --> 00:39:14,720
Hivyo ni zinageuka kuwa wakati sisi
iterate kutoka 0 hadi kwenye kamba

882
00:39:14,720 --> 00:39:17,424
length-- kwanza kabisa, i
kuanza mbali katika 0, kwa sababu

883
00:39:17,424 --> 00:39:18,840
ya hii umri wa shule ya kitanzi kitu.

884
00:39:18,840 --> 00:39:22,400
Hivyo tu kwa unyenyekevu, hebu
kudhani kuwa mstari wa kwanza wa kanuni

885
00:39:22,400 --> 00:39:23,760
ni kweli tu hii, haki.

886
00:39:23,760 --> 00:39:26,080
Kama i ni sifuri, na kuongeza sifuri
na kitu labda

887
00:39:26,080 --> 00:39:27,540
si kwenda kuwa na athari.

888
00:39:27,540 --> 00:39:28,560
>> Kwa hiyo kile ni maneno yako?

889
00:39:28,560 --> 00:39:31,600
Ni zinageuka kuwa nyota
operator katika mazingira haya

890
00:39:31,600 --> 00:39:33,700
ni dereference
operator, ambayo ni tu

891
00:39:33,700 --> 00:39:37,530
njia dhana ya kusema kwenda
kwa anwani ifuatayo.

892
00:39:37,530 --> 00:39:42,080
Hivyo kama s ni ya kwanza anuani
tabia katika hii chunk ya kumbukumbu,

893
00:39:42,080 --> 00:39:43,630
* s njia kwenda huko.

894
00:39:43,630 --> 00:39:45,630
Na kwa sababu tumekuwa inayotolewa
picha kwa njia hii,

895
00:39:45,630 --> 00:39:47,430
unaweza kupitisha
kufuatia mfano wa akili.

896
00:39:47,430 --> 00:39:51,030
Kama hii ni s, na kusema * s, s *
aina ya kama chutes na ladders,

897
00:39:51,030 --> 00:39:54,540
kama unakumbuka mchezo kutoka utotoni,
ni kama kufuata mshale na kwenda

898
00:39:54,540 --> 00:39:55,570
kwa mahali.

899
00:39:55,570 --> 00:39:57,080
>> * t ni kitu kimoja.

900
00:39:57,080 --> 00:39:59,855
Hivyo kuanza hapa, kwenda chunk wake.

901
00:39:59,855 --> 00:40:03,350
Siwezi tu kuteka juu ya
screen hii kwa njia hiyo.

902
00:40:03,350 --> 00:40:05,560
* t maana ya kwenda hapa.

903
00:40:05,560 --> 00:40:08,830
Na kisha, kwa kitanzi ni
akisema hoja tabia hii hapa,

904
00:40:08,830 --> 00:40:11,330
hoja tabia hii hapa,
hoja tabia hii hapa.

905
00:40:11,330 --> 00:40:12,890
Lakini jinsi gani mimi kufanya hivyo incrementation?

906
00:40:12,890 --> 00:40:15,430
Mimi haja ya kuondoa nini mimi tu kufutwa.

907
00:40:15,430 --> 00:40:18,140
Hii ni nini ujumla aitwaye
pointer arithmetic, ambayo

908
00:40:18,140 --> 00:40:20,040
ina maana hesabu na anwani.

909
00:40:20,040 --> 00:40:22,460
>> Kama, katika hii kwa kitanzi,
Mimi kuendelea incrementing i,

910
00:40:22,460 --> 00:40:26,880
na s ni anwani na t ni
mitaani, kama mimi tu kuendelea kuongeza 1,

911
00:40:26,880 --> 00:40:31,406
kwamba tu ina maana kusonga mbele,
na mbele, na mbele katika kumbukumbu.

912
00:40:31,406 --> 00:40:34,030
Ni kama Oxford Street,
mitaani kwamba jengo CS ni juu ya.

913
00:40:34,030 --> 00:40:36,490
Majengo CS ni saa 33 Oxford Street.

914
00:40:36,490 --> 00:40:39,870
Hivyo kama ungekuwa kufanya 33
Oxford Street pamoja na 1,

915
00:40:39,870 --> 00:40:42,870
ambayo huleta wewe kwa 34 Oxford
Mitaani, basi 35 Oxford Street,

916
00:40:42,870 --> 00:40:46,380
kisha 36 Oxford Street, chochote wale
majengo kwa kweli ni - kama zipo.

917
00:40:46,380 --> 00:40:50,540
Na hivyo, kwamba ni yote sisi ni kufanya
hapa na pointer hesabu.

918
00:40:50,540 --> 00:40:53,820
>> Hivyo ni njia super arcane
ya kuonyesha sisi wenyewe.

919
00:40:53,820 --> 00:40:56,160
Lakini yote yale yanayotokea
chini ya Hood

920
00:40:56,160 --> 00:40:59,330
ni kufuatia tu anwani hizi,
kama zifuatazo ramani, kama wewe,

921
00:40:59,330 --> 00:41:02,692
au kufuatia mishale kama
tumekuwa inayotolewa kwenye screen.

922
00:41:02,692 --> 00:41:04,910
OK, mengi Digest.

923
00:41:04,910 --> 00:41:10,410
Swali lolote juu ya syntax, dhana,
kuyatumia, malloc, au kama.

924
00:41:10,410 --> 00:41:11,480
Naam, hapa kwanza.

925
00:41:11,480 --> 00:41:13,755
>> Watazamaji: Hivyo ambapo kwamba
anasema * t sawa na toupper * t,

926
00:41:13,755 --> 00:41:15,575
ni kwamba kwenda capitalize
zote herufi au just--

927
00:41:15,575 --> 00:41:17,283
>> DAVID J. Malan: Ah,
mzuri swali.

928
00:41:17,283 --> 00:41:19,805
Hivyo katika mstari huu hapa, 31,
hii ni kwenda capitalize

929
00:41:19,805 --> 00:41:21,430
barua ya kwanza au yote ya barua.

930
00:41:21,430 --> 00:41:23,460
Basi hebu kujibu kwamba kwa kwenda
nyuma ya kanuni kwanza.

931
00:41:23,460 --> 00:41:26,168
Na kanuni za kwanza hapa nina maana
tu kwenda ufafanuzi msingi

932
00:41:26,168 --> 00:41:27,000
ya nini wanaohusika.

933
00:41:27,000 --> 00:41:29,770
Hivyo toupper ni kazi
kwamba herufi Char.

934
00:41:29,770 --> 00:41:30,530
Hayo ni yote.

935
00:41:30,530 --> 00:41:36,740
* t ina maana kwenda first--
kwenda anuani katika t.

936
00:41:36,740 --> 00:41:40,350
Hivyo, katika picha, kama hii ni chunk
ya kumbukumbu sisi zilizotengwa kwa malloc,

937
00:41:40,350 --> 00:41:43,310
na hii ni t, t * ina maana kwenda hapa.

938
00:41:43,310 --> 00:41:46,710
>> Wakati huo huo, wewe ni kupita
kwamba thamani, lowercase m

939
00:41:46,710 --> 00:41:50,040
kwa toupper, wewe ni kupata nyuma
mji mkuu M, ambapo ni wewe kuweka?

940
00:41:50,040 --> 00:41:52,410
Wewe ni kuweka katika eneo hilo hilo.

941
00:41:52,410 --> 00:41:55,540
Na hivyo kwa kuwa mantiki ya wale
ufafanuzi wa msingi ni tu

942
00:41:55,540 --> 00:41:58,792
kuyafanyia barua ya kwanza
isipokuwa iterate kwa i au a

943
00:41:58,792 --> 00:42:02,000
kwa kitanzi au kitanzi wakati, si kwenda
kufanya kitu chochote zaidi ya kuuliza hilo.

944
00:42:02,000 --> 00:42:02,583
Nzuri swali.

945
00:42:02,583 --> 00:42:03,237
Yeah?

946
00:42:03,237 --> 00:42:05,369
>> Watazamaji: Kwa nini unatumia
dereference njia badala ya

947
00:42:05,369 --> 00:42:05,979
safu?

948
00:42:05,979 --> 00:42:07,395
>> DAVID J. Malan: Ah, nzuri swali.

949
00:42:07,395 --> 00:42:10,672
Kwa nini wewe kutumia dereference
Njia badala ya mbinu safu?

950
00:42:10,672 --> 00:42:12,130
Hakuna sababu maalum, kuwa waaminifu.

951
00:42:12,130 --> 00:42:15,290
Na, kwa kweli, kwa hili
namna ya mfano wa kulia,

952
00:42:15,290 --> 00:42:17,556
Mimi akisema maamuzi tu
Mpango ngumu zaidi,

953
00:42:17,556 --> 00:42:19,680
macho zaidi ni glazing juu,
Watu kuangalia nje

954
00:42:19,680 --> 00:42:22,830
kwa sababu hii inaonekana super arcane, lakini
hata kama ni kufanya kitu kimoja.

955
00:42:22,830 --> 00:42:26,695
Na hivyo, kusema ukweli, hii ni
ufumbuzi usiokuwa kuibua tata

956
00:42:26,695 --> 00:42:27,320
tatizo.

957
00:42:27,320 --> 00:42:29,580
>> Bado kubuni nzuri,
tano kati ya watano kwa kubuni,

958
00:42:29,580 --> 00:42:33,140
kama ni katika mabano
nukuu au pointer nukuu.

959
00:42:33,140 --> 00:42:36,299
But-- hasa wakati tunapata
baadaye katika mwendo katika pset 5

960
00:42:36,299 --> 00:42:39,340
wakati sisi kutekeleza kwamba kamusi kwamba
Nimekuwa zilizotajwa michache ya times--

961
00:42:39,340 --> 00:42:42,300
tutaweza kweli huduma ya juu
anwani kumbukumbu kiwango cha chini

962
00:42:42,300 --> 00:42:44,140
kwamba sisi kweli kuelewa
nini kinaendelea.

963
00:42:44,140 --> 00:42:48,300
>> Lakini, kwa sasa, ni zamu nje kwamba hii
mstari wa kanuni mabano mraba hapa

964
00:42:48,300 --> 00:42:49,900
si kweli zipo.

965
00:42:49,900 --> 00:42:52,230
Wao ni kile kinachoitwa
sukari kisintaksia, ambayo

966
00:42:52,230 --> 00:42:58,390
ni njia tu weirdly baridi ya kusema
compiler waongofu mabano mraba kuwa

967
00:42:58,390 --> 00:43:00,420
kwamba kujieleza hisabati.

968
00:43:00,420 --> 00:43:02,660
Hivyo ni mkataba wa binadamu
kuwa na uwezo wa kuandika tu

969
00:43:02,660 --> 00:43:04,220
sana user-kirafiki mabano haya.

970
00:43:04,220 --> 00:43:06,850
Lakini nini compiler, Clang,
ni kweli kufanya wakati wowote

971
00:43:06,850 --> 00:43:10,970
kuandika nini yalionyesha katika mstari
24, chini ya Hood ni kweli

972
00:43:10,970 --> 00:43:12,330
kuwageuza kwa hili.

973
00:43:12,330 --> 00:43:16,200
Ni tu zaidi utamu kama binadamu
kusoma na kuandika kificho kama mstari 24.

974
00:43:16,200 --> 00:43:18,530
Lakini hatimaye wale
magurudumu mafunzo pia kufika mbali

975
00:43:18,530 --> 00:43:21,780
wakati wenyewe faraja ya mtu anapata nguvu.

976
00:43:21,780 --> 00:43:27,240
>> Haki wote, hivyo basi kukumbuka kwamba hii
ilikuwa ni aina ya tatizo kubwa

977
00:43:27,240 --> 00:43:27,807
sisi mbio katika.

978
00:43:27,807 --> 00:43:30,640
Na hiyo ndiyo umesababisha zima huu
mazungumzo damn kuhusu kuyatumia,

979
00:43:30,640 --> 00:43:32,340
na anwani, na kuiga mambo.

980
00:43:32,340 --> 00:43:35,410
Ilikuwa ni kwa sababu sisi tripped juu
kijinga, kijinga suala hili, ambapo

981
00:43:35,410 --> 00:43:38,830
Mimi kutekelezwa logically-- na Lauren
hapa kwenye demo na maji ya machungwa

982
00:43:38,830 --> 00:43:43,770
katika milk-- kikamilifu
kazi algorithmically sahihi

983
00:43:43,770 --> 00:43:47,010
kwa swapping vigezo mbili '
maadili, lakini jambo damn

984
00:43:47,010 --> 00:43:50,550
hawakuwa na yoyote ya kuendelea, au
kudumu, na athari kwenye kanuni yangu.

985
00:43:50,550 --> 00:43:51,820
>> Na kwa nini ilikuwa hivyo?

986
00:43:51,820 --> 00:43:54,650
Kwa kifupi, kwa nini hili
utekelezaji wa wabadilishane

987
00:43:54,650 --> 00:43:58,740
mantiki sahihi, lakini ina athari hakuna
juu ya vigezo kwamba ni kupita hiyo,

988
00:43:58,740 --> 00:44:01,119
kama x na y kwa kuu?

989
00:44:01,119 --> 00:44:02,410
Ilikuwa kiini cha suala gani?

990
00:44:02,410 --> 00:44:02,909
Yeah?

991
00:44:02,909 --> 00:44:05,532
Watazamaji: Kwa sababu kutofautiana alifanya
nakala za kutofautiana katika kupitisha

992
00:44:05,532 --> 00:44:06,240
kupitia kazi.

993
00:44:06,240 --> 00:44:09,060
>> DAVID J. Malan: Hasa, wakati kupita
vigezo katika kazi, au hoja

994
00:44:09,060 --> 00:44:11,030
ndani ya kazi, wao uko
wanapita nakala, ambayo

995
00:44:11,030 --> 00:44:14,770
ina maana unaweza kupata kufanana kuangalia
mfano wa bits kwa wote x na y,

996
00:44:14,770 --> 00:44:15,955
aitwaye hapa a na b.

997
00:44:15,955 --> 00:44:18,080
Na unaweza kufanya kitu chochote
unataka na nakala hizo,

998
00:44:18,080 --> 00:44:20,657
lakini wao wanaenda kuwa hakuna
athari juu ya wito kazi.

999
00:44:20,657 --> 00:44:22,990
Na, kwa kweli, tulianzisha kwamba
picha kwenye screen, kukumbuka

1000
00:44:22,990 --> 00:44:25,520
Mara ya mwisho, ambapo kama wewe
kweli wanafikiri kuhusu nini

1001
00:44:25,520 --> 00:44:28,570
kinachoendelea chini hood-- kama
hii ni kumbukumbu ya kompyuta yako,

1002
00:44:28,570 --> 00:44:31,650
na chini hapa ni chunk ya
kumbukumbu inatumiwa kwa kuu,

1003
00:44:31,650 --> 00:44:34,020
hii ni chunk ya
kumbukumbu inatumiwa kwa wabadilishane,

1004
00:44:34,020 --> 00:44:37,090
na hivyo hata kama ana kuu
vigezo mbili, x na y,

1005
00:44:37,090 --> 00:44:41,840
wabadilishane wanaweza kuwa kufanana kuangalia
maadili, wote wawili ambao ni 1 na 2,

1006
00:44:41,840 --> 00:44:44,520
lakini wao ni kabisa
chunks mbalimbali za kumbukumbu.

1007
00:44:44,520 --> 00:44:46,130
>> Kwa hiyo, tunahitaji ufumbuzi wa hili.

1008
00:44:46,130 --> 00:44:51,580
Na kusema ukweli, inaweza kuonekana kwamba sisi sasa
na ufumbuzi wa tatizo hili, haki.

1009
00:44:51,580 --> 00:44:55,760
Kama sisi sasa wana uwezo wa
kuendesha mambo kwa njia ya anwani

1010
00:44:55,760 --> 00:44:59,310
na, aina ya chutes na ladders
style, kufuata mishale hizi

1011
00:44:59,310 --> 00:45:02,820
na kwenda popote tunataka
katika kumbukumbu, hawakuweza sisi

1012
00:45:02,820 --> 00:45:06,220
kutatua tatizo hili kwa
kupita kutoka kuu wabadilishane

1013
00:45:06,220 --> 00:45:09,650
si maadili tunataka
wabadilishane, lakini tu intuitively

1014
00:45:09,650 --> 00:45:11,630
nini inaweza sisi kupita wabadilishane badala yake?

1015
00:45:11,630 --> 00:45:12,620
>> [INTERPOSING SAUTI]

1016
00:45:12,620 --> 00:45:15,244
>> DAVID J. Malan: Kwa nini si sisi tu
kuupitisha anwani, sawa?

1017
00:45:15,244 --> 00:45:17,470
Mbona sisi kutoa wabadilishane a
hazina ramani, kama wewe,

1018
00:45:17,470 --> 00:45:20,950
ambayo inaongoza kwa
maadili halisi x na y.

1019
00:45:20,950 --> 00:45:24,340
Hebu wabadilishane, kweli mabadiliko
wale bits awali, badala ya

1020
00:45:24,340 --> 00:45:26,797
tu kupita nakala za vipande.

1021
00:45:26,797 --> 00:45:29,130
Na hivyo, kwa kweli, kwamba ni nini
kwenda kuwa ufumbuzi.

1022
00:45:29,130 --> 00:45:31,899
Hii toleo hapa ni
wazi mbaya na kiujanja.

1023
00:45:31,899 --> 00:45:35,190
Na sasa, katika mtazamo wa kwanza, ni tu inaonekana
kama sisi aliongeza rundo la nyota nasibu

1024
00:45:35,190 --> 00:45:37,106
na shilingi vidole wetu
kuwa itakuwa kukusanya.

1025
00:45:37,106 --> 00:45:38,460
Lakini, ingekuwa sasa kukusanya.

1026
00:45:38,460 --> 00:45:40,090
>> Lakini hebu angalia maana ya mambo haya.

1027
00:45:40,090 --> 00:45:43,990
Na, kwa bahati mbaya, waandishi wa
C inaweza wamechagua alama nyingine

1028
00:45:43,990 --> 00:45:46,380
kufanya hii ndogo
wazi, lakini nyota operator

1029
00:45:46,380 --> 00:45:48,610
ina maana tofauti katika
mazingira mawili tofauti.

1030
00:45:48,610 --> 00:45:50,890
Na tumeona zote mbili,
lakini hebu kutofautisha.

1031
00:45:50,890 --> 00:45:55,310
>> Hivyo hadi saa juu huko,
wakati mimi yamebadilika a na b

1032
00:45:55,310 --> 00:46:00,470
asiwe int katika mbaya
toleo int nyota, a na b,

1033
00:46:00,470 --> 00:46:01,740
hapo awali, walikuwa integers.

1034
00:46:01,740 --> 00:46:05,752
Na b ni nini sasa katika
nzuri, kijani toleo la?

1035
00:46:05,752 --> 00:46:06,900
Wao ni anwani.

1036
00:46:06,900 --> 00:46:09,610
Anwani ya nini, kuwa wazi?

1037
00:46:09,610 --> 00:46:10,770
Anwani ya integers.

1038
00:46:10,770 --> 00:46:12,520
Hivyo ukweli kwamba mimi nina
akisema int nyota njia

1039
00:46:12,520 --> 00:46:15,440
hii ni pepe ya
integer, hasa.

1040
00:46:15,440 --> 00:46:19,120
>> Hivyo sasa taarifa katika mstari wa kanuni,
kitu kingine imebadilika mno.

1041
00:46:19,120 --> 00:46:22,770
TMP anakaa huo, kwa sababu
ni tu integer muda,

1042
00:46:22,770 --> 00:46:24,110
hakuna kumbukumbu uchawi hapo.

1043
00:46:24,110 --> 00:46:26,370
Lakini sasa mahitaji nyota.

1044
00:46:26,370 --> 00:46:28,560
Na, kwa kweli, kila
kutaja wengine wa na b,

1045
00:46:28,560 --> 00:46:31,780
taarifa kwamba yote hiyo ni
kubadilisha kutoka nyekundu na kijani

1046
00:46:31,780 --> 00:46:34,209
ni kwamba mimi nina prefixing
vigezo wale wenye nyota.

1047
00:46:34,209 --> 00:46:35,750
Kwa sababu mimi sitaki nakala na b.

1048
00:46:35,750 --> 00:46:40,350
Kwa sababu kama mimi tu nakala na b na wabadilishane
a na b, je, Mimi kwa kweli swapping?

1049
00:46:40,350 --> 00:46:43,760
Anwani Tu, nataka wabadilishane
nini katika wale anwani.

1050
00:46:43,760 --> 00:46:44,860
Nataka kwenda huko.

1051
00:46:44,860 --> 00:46:48,000
Na hivyo nyota operator
ndani ya kazi yangu,

1052
00:46:48,000 --> 00:46:51,700
si ndani ya orodha parameter,
maana wewe kwenda wale anwani

1053
00:46:51,700 --> 00:46:54,490
na kweli mabadiliko maadili hayo.

1054
00:46:54,490 --> 00:46:56,500
>> Kwa hiyo kile anafanya picha
sasa kuangalia kama badala yake.

1055
00:46:56,500 --> 00:47:03,250
Naam, kama badala mimi nina kupita
katika kwa na b si 1 na 2--

1056
00:47:03,250 --> 00:47:05,790
Mimi kwa kweli haja ya kuongeza
mengine ufafanuzi moja hapa.

1057
00:47:05,790 --> 00:47:09,030
Hivyo kudhani kuwa chunk hii
ya kumbukumbu ni katika eneo 10.

1058
00:47:09,030 --> 00:47:12,960
>> Hii ni katika eneo 11, lakini hii
ni kidogo ya kurahisisha,

1059
00:47:12,960 --> 00:47:18,900
Mimi sasa una maamuzi mawili kufanya mimi kupita x
na y au gani mimi kupita anwani zao?

1060
00:47:18,900 --> 00:47:22,500
Kama mimi kupita anwani zao
kama hii, mimi tu

1061
00:47:22,500 --> 00:47:25,390
sasa haja ya kutekeleza
wabadilishane kwa kificho kijani

1062
00:47:25,390 --> 00:47:29,080
hivyo kwamba wakati anaona na wakati
anaona b, haina nakala tu na b

1063
00:47:29,080 --> 00:47:30,540
na hoja maziwa na maji ya machungwa.

1064
00:47:30,540 --> 00:47:32,664
Maziwa na juisi ya machungwa
mfano sasa umekwisha,

1065
00:47:32,664 --> 00:47:35,060
kwa sababu wale ni vikombe
ya ramani maji na si.

1066
00:47:35,060 --> 00:47:37,750
Sisi badala haja ya kwenda
kushughulikia 10 na sisi

1067
00:47:37,750 --> 00:47:42,420
haja ya kwenda kushughulikia 11, na
kisha kufanya kwamba swapping mantiki.

1068
00:47:42,420 --> 00:47:45,580
>> Hivyo mantiki ni sawa, lakini
tunahitaji njia tofauti kidogo

1069
00:47:45,580 --> 00:47:47,160
ya kupata vigezo hizo.

1070
00:47:47,160 --> 00:47:52,400
Na hivyo katika mwisho, nini
mpango ina kuangalia kama ni hii.

1071
00:47:52,400 --> 00:47:56,610
Katika swap.c literally kunakiliwa
na pasted toleo la kijani.

1072
00:47:56,610 --> 00:47:58,450
Lakini mimi haja ya kufanya mabadiliko moja.

1073
00:47:58,450 --> 00:48:00,180
Siyo kutosha tu kubadili wabadilishane.

1074
00:48:00,180 --> 00:48:03,830
Nini mstari mwingine wa kanuni
nahitaji kubadilika?

1075
00:48:03,830 --> 00:48:04,330
Yeah?

1076
00:48:04,330 --> 00:48:05,770
>> Watazamaji: wapi inachukua hoja.

1077
00:48:05,770 --> 00:48:07,603
>> DAVID J. Malan: wapi
inachukua hoja yake.

1078
00:48:07,603 --> 00:48:09,985
Hivyo kama mimi kitabu juu ya kuu, mimi
Huwezi tu kupita katika x na y,

1079
00:48:09,985 --> 00:48:12,820
na, mimi ahadi, jana
kipande cha syntax mpya leo.

1080
00:48:12,820 --> 00:48:17,200
Mimi haja ya kupita katika x na si
y lakini pepe ya x na y.

1081
00:48:17,200 --> 00:48:20,400
Na zinageuka, alama
kwamba waandishi wa C waliamua

1082
00:48:20,400 --> 00:48:23,860
ni kama matumizi ampersand hapa, si kwa
kuchanganyikiwa na bitwise ampersand,

1083
00:48:23,860 --> 00:48:27,130
kama matumizi ampersand
hapa na ampersand hapa,

1084
00:48:27,130 --> 00:48:29,570
hii takwimu za nje kwa ajili yenu,
nini pepe ya x,

1085
00:48:29,570 --> 00:48:31,740
labda ni 10, nini
anuani ya y, labda ni

1086
00:48:31,740 --> 00:48:35,400
11, na hupita wale walio katika badala yake.

1087
00:48:35,400 --> 00:48:37,210
>> Hivyo mengi ya kunyonya wote mara moja.

1088
00:48:37,210 --> 00:48:40,190
Lakini hebu angalia sasa haraka katika
iliyobaki dakika nne wetu

1089
00:48:40,190 --> 00:48:42,150
ambapo mambo yanaweza kwenda kombo.

1090
00:48:42,150 --> 00:48:45,120
Na kama kando, kwa kweli
Mimi alichukua picha hii,

1091
00:48:45,120 --> 00:48:46,920
TF alichukua picha hii mwaka mmoja au miwili iliyopita.

1092
00:48:46,920 --> 00:48:49,190
Hivyo hii ni kona nyuma
ya Eliot Dining Hall.

1093
00:48:49,190 --> 00:48:52,310
Kuyatumia ni labda gumu
mada hiyo sisi cover katika CS50.

1094
00:48:52,310 --> 00:48:54,810
Hivyo kama wewe kuwa na wasiwasi aina
ya mteremko ni kama labda ni

1095
00:48:54,810 --> 00:48:56,770
zaidi ya magongo fimbo
kama hii, kutambua

1096
00:48:56,770 --> 00:49:00,160
sisi ni aina ya inakaribia kilele katika
suala la utata wa dhana.

1097
00:49:00,160 --> 00:49:02,300
>> Na mimi kuleta hii
picha, kwa sababu Naapa

1098
00:49:02,300 --> 00:49:05,920
mungu, katika kuanguka 1996, wakati mimi alichukua
CS50 na mafundisho mwenzangu,

1099
00:49:05,920 --> 00:49:09,620
Nishat Mehta, Yesu akakaa yangu chini katika
kona ya Eliot D. Hall juu ya chakula cha mchana,

1100
00:49:09,620 --> 00:49:12,330
au cha jioni, au kitu kujaribu
kunisaidia kuelewa kuyatumia.

1101
00:49:12,330 --> 00:49:16,520
Na hii ni mahali ambapo mimi nilikuwa wiki baada ya
kuletwa katika hotuba wakati

1102
00:49:16,520 --> 00:49:18,170
Mimi hatimaye kueleweka kuyatumia.

1103
00:49:18,170 --> 00:49:20,590
Na mimi nina matumaini kwamba hii
mapenzi click mbali mapema kwa ajili yenu.

1104
00:49:20,590 --> 00:49:23,540
Lakini kutambua hili kabisa miongoni mwa
mada ya kisasa zaidi

1105
00:49:23,540 --> 00:49:24,420
tumekuwa inaonekana katika.

1106
00:49:24,420 --> 00:49:25,819
Lakini ni miongoni mwa nguvu zaidi.

1107
00:49:25,819 --> 00:49:28,860
Na wakati kupata hilo, ni kweli wote
tu kwenda hatimaye kuja pamoja.

1108
00:49:28,860 --> 00:49:31,460
Hivyo mapumziko uhakika hana
haja ya kuzama yote katika leo.

1109
00:49:31,460 --> 00:49:32,980
>> Hivyo hapa ni mpango wa mwisho
tunakwenda kuangalia.

1110
00:49:32,980 --> 00:49:35,605
Na tunakwenda kuishia na
Dakika haraka tatu ya claymation

1111
00:49:35,605 --> 00:49:37,030
yaliyotolewa na rafiki yetu, Nick Parlante.

1112
00:49:37,030 --> 00:49:41,440
Hapa ni mpango, kwamba juu ya mbili juu
mistari inatangaza x kutofautiana na y.

1113
00:49:41,440 --> 00:49:44,780
Wote wawili ambao ni anwani za
integers, AKA kuyatumia.

1114
00:49:44,780 --> 00:49:48,125
Sisi kisha kutenga kutosha
kumbukumbu kuhifadhi int

1115
00:49:48,125 --> 00:49:51,344
na kuhifadhi anwani
ya kwamba kumbukumbu katika x.

1116
00:49:51,344 --> 00:49:53,260
Hivyo, ni rahisi hata
kuliko mfano kabla.

1117
00:49:53,260 --> 00:49:56,100
Nipe ka nne ya kumbukumbu,
hiyo ni ukubwa wa int,

1118
00:49:56,100 --> 00:49:58,000
na kuweka anwani hiyo katika x.

1119
00:49:58,000 --> 00:50:01,070
Hii ina maana hapa mstari
kwenda anuani katika x

1120
00:50:01,070 --> 00:50:05,270
na kuweka maana ya
maisha, namba 42 hapo.

1121
00:50:05,270 --> 00:50:07,710
Lakini mstari huu wasiwasi mimi.

1122
00:50:07,710 --> 00:50:12,620
Nyota y ina maana kwenda anuani katika y,
na kuweka idadi unlucky 13 huko.

1123
00:50:12,620 --> 00:50:15,780
Kwa nini ni hatari, katika hatua hii
katika story-- japo kwa kasi aliiambia

1124
00:50:15,780 --> 00:50:17,980
katika dakika wetu waning
here-- kwa nini ni mbaya

1125
00:50:17,980 --> 00:50:19,660
kwangu kusema, kwenda anuani katika y?

1126
00:50:19,660 --> 00:50:21,077
>> Watazamaji: Una si [inaudible].

1127
00:50:21,077 --> 00:50:22,910
DAVID J. Malan: Mimi sina
kuweka chochote katika y.

1128
00:50:22,910 --> 00:50:25,520
Kwa hiyo kile ni thamani ya y,
katika hatua hii ya hadithi?

1129
00:50:25,520 --> 00:50:26,570
Sisi hatuna wazo.

1130
00:50:26,570 --> 00:50:29,190
Ni baadhi ya thamani ya takataka
na wala haina Binky kujua.

1131
00:50:29,190 --> 00:50:32,532
Kama tunaweza kuishia juu ya kumbuka hii.

1132
00:50:32,532 --> 00:50:34,832
>> [VIDEO avspelning]

1133
00:50:34,832 --> 00:50:36,500
>> -Hey, Binky, kuamka.

1134
00:50:36,500 --> 00:50:39,140
Ni wakati wa pointer na furaha.

1135
00:50:39,140 --> 00:50:40,210
>> -Nini Hiyo?

1136
00:50:40,210 --> 00:50:41,690
Kujifunza kuhusu kuyatumia?

1137
00:50:41,690 --> 00:50:43,570
Loo, goody.

1138
00:50:43,570 --> 00:50:46,600
>> -Naam, Kupata kuanza, mimi nadhani tuko
kwenda haja ya kuyatumia wanandoa.

1139
00:50:46,600 --> 00:50:47,380
>> -SAWA.

1140
00:50:47,380 --> 00:50:51,120
Kanuni hii inatenga kuyatumia mbili
ambayo inaweza kumweka kwa integers.

1141
00:50:51,120 --> 00:50:53,557
>> -OK, Vizuri naona
kuyatumia mbili, lakini wao

1142
00:50:53,557 --> 00:50:55,140
hawaonekani kuwa akizungumzia chochote.

1143
00:50:55,140 --> 00:50:55,970
>> -yaani Ni haki.

1144
00:50:55,970 --> 00:50:58,100
Awali kuyatumia
hawana uhakika na kitu chochote.

1145
00:50:58,100 --> 00:51:00,950
Mambo wao kumweka kwa watu
aitwaye pointees na kuweka yao juu

1146
00:51:00,950 --> 00:51:02,330
ni hatua tofauti.

1147
00:51:02,330 --> 00:51:03,210
>> -Oh, Haki, haki.

1148
00:51:03,210 --> 00:51:03,940
Nilijua kuwa.

1149
00:51:03,940 --> 00:51:05,730
Pointees ni tofauti.

1150
00:51:05,730 --> 00:51:08,310
Hivyo ni jinsi gani kutenga pointee?

1151
00:51:08,310 --> 00:51:11,960
>> -OK, Vizuri hii kutenga kificho
mpya integer pointee,

1152
00:51:11,960 --> 00:51:15,050
na seti sehemu hii x kwa uhakika na hilo.

1153
00:51:15,050 --> 00:51:16,240
>> -Hey, Kwamba inaonekana zaidi.

1154
00:51:16,240 --> 00:51:17,743
Hivyo kufanya hivyo kufanya kitu.

1155
00:51:17,743 --> 00:51:23,580
>> -OK, Mimi itabidi dereference pointer x kwa
kuhifadhi idadi 42 katika pointee wake.

1156
00:51:23,580 --> 00:51:27,130
Kwa hila hii, mimi itabidi yangu
uchawi wand ya dereferencing.

1157
00:51:27,130 --> 00:51:30,200
>> -Wako Uchawi wand ya dereferencing?

1158
00:51:30,200 --> 00:51:32,310
Uh, kwamba, hiyo ni kubwa.

1159
00:51:32,310 --> 00:51:34,270
>> -Hii Ni nini kificho inaonekana kama.

1160
00:51:34,270 --> 00:51:35,970
Mimi itabidi kuanzisha idadi and--

1161
00:51:35,970 --> 00:51:37,070
>> [POP SOUND]

1162
00:51:37,070 --> 00:51:39,140
>> -Hey, Angalia kuna unaendelea.

1163
00:51:39,140 --> 00:51:43,980
Hivyo, kufanya dereference juu ya x ifuatavyo
mshale wa kupata pointee wake.

1164
00:51:43,980 --> 00:51:46,150
Katika kesi hiyo, kuhifadhi 42 katika huko.

1165
00:51:46,150 --> 00:51:50,700
Hey, jaribu kutumia kuhifadhi idadi
13 kupitia pointer mengine, y.

1166
00:51:50,700 --> 00:51:51,840
>> -SAWA.

1167
00:51:51,840 --> 00:51:56,270
Mimi itabidi kwenda juu hapa y,
na kupata namba 13 seti up.

1168
00:51:56,270 --> 00:52:00,380
Na kisha kuchukua wand ya
dereferencing na just--

1169
00:52:00,380 --> 00:52:01,646
>> [Buzzer SOUND]

1170
00:52:01,646 --> 00:52:04,080
>> -Oh, Hey kwamba hakuwa na kazi.

1171
00:52:04,080 --> 00:52:06,470
Kusema, uh, Binky, sijui
kufikiri dereferencing

1172
00:52:06,470 --> 00:52:10,850
y ni wazo nzuri, kwa sababu kuweka
up pointee ni hatua tofauti.

1173
00:52:10,850 --> 00:52:12,480
Na sidhani kama sisi milele alifanya hivyo.

1174
00:52:12,480 --> 00:52:14,620
>> -Hmm, Hatua nzuri.

1175
00:52:14,620 --> 00:52:19,810
>> -Yeah, Sisi zilizotengwa pointer, y, lakini
sisi kamwe kuweka kwa uhakika na pointee.

1176
00:52:19,810 --> 00:52:21,590
>> -Hmm, Mwangalifu sana.

1177
00:52:21,590 --> 00:52:23,215
-Hey, Wewe kutafuta nzuri huko, Binky.

1178
00:52:23,215 --> 00:52:26,390
Je, unaweza kurekebisha ili y pointi
kwa pointee sawa na x.

1179
00:52:26,390 --> 00:52:29,290
>> -Sure, Mimi kutumia wand uchawi wangu
ya pointer zoezi.

1180
00:52:29,290 --> 00:52:31,970
>> -Je Kwamba kwenda kuwa
tatizo, kama kabla?

1181
00:52:31,970 --> 00:52:33,790
>> -Hakuna, Hii ​​haina kugusa pointees.

1182
00:52:33,790 --> 00:52:35,840
Ni tu mabadiliko pointer moja
kwa uhakika na huo thing--

1183
00:52:35,840 --> 00:52:36,465
>> [Sauti popping]

1184
00:52:36,465 --> 00:52:37,450
--as mwingine.

1185
00:52:37,450 --> 00:52:38,440
>> -Oh, Naona.

1186
00:52:38,440 --> 00:52:41,200
Sasa y pointi kwenye sehemu moja kama x.

1187
00:52:41,200 --> 00:52:42,950
Hivyo, ngoja, sasa y ni fasta.

1188
00:52:42,950 --> 00:52:44,110
Ina pointee.

1189
00:52:44,110 --> 00:52:47,779
Hivyo unaweza kujaribu wand ya
dereferencing tena kwa kutuma 13 juu.

1190
00:52:47,779 --> 00:52:51,110
>> -Oh, Sawa, hapa unaendelea.

1191
00:52:51,110 --> 00:52:52,330
>> -Hey, Kuangalia kwamba.

1192
00:52:52,330 --> 00:52:53,570
Sasa dereferencing kazi juu y.

1193
00:52:53,570 --> 00:52:57,900
Na kwa sababu kuyatumia wanashiriki
kwamba pointee moja, wao wote kuona 13.

1194
00:52:57,900 --> 00:52:59,952
>> -Yeah, Kushirikiana, uh, chochote.

1195
00:52:59,952 --> 00:53:01,535
Hivyo, ni sisi kwenda kubadili maeneo sasa?

1196
00:53:01,535 --> 00:53:03,730
>> -Oh, Angalia tuko nje ya muda.

1197
00:53:03,730 --> 00:53:04,660
>> -But--

1198
00:53:04,660 --> 00:53:06,520
>> -Tu kumbuka tatu sheria pointer.

1199
00:53:06,520 --> 00:53:09,550
Namba 1, muundo wa msingi
ni kwamba una pointer,

1200
00:53:09,550 --> 00:53:11,630
na inaelekeza juu ya pointee kwa.

1201
00:53:11,630 --> 00:53:13,740
Lakini pointer na
pointee ni tofauti.

1202
00:53:13,740 --> 00:53:15,620
Na makosa ya kawaida
ni kuanzisha pointer

1203
00:53:15,620 --> 00:53:18,000
lakini kusahau kuwapa pointee.

1204
00:53:18,000 --> 00:53:21,170
>> Idadi 2, pointer dereferencing
kuanza saa pointer

1205
00:53:21,170 --> 00:53:24,020
na ifuatavyo mshale wake juu ya
kupata pointee wake.

1206
00:53:24,020 --> 00:53:27,815
Kama sisi wote kujua, hii kazi tu kama kuna
ni pointee, ambayo aina ya anapata nyuma

1207
00:53:27,815 --> 00:53:29,260
kutawala namba 1.

1208
00:53:29,260 --> 00:53:31,990
>> Namba 3, pointer
zoezi inachukua moja pointer

1209
00:53:31,990 --> 00:53:35,330
na mabadiliko hayo kwa uhakika na
pointee sawa kama pointer mwingine.

1210
00:53:35,330 --> 00:53:37,150
Kwa hiyo baada ya zoezi,
kuyatumia mbili

1211
00:53:37,150 --> 00:53:40,927
uhakika na pointee huo,
wakati mwingine kwamba wito kugawana.

1212
00:53:40,927 --> 00:53:42,510
Na kwamba wote kuna hiyo, kwa kweli.

1213
00:53:42,510 --> 00:53:43,130
Bye-bye sasa.

1214
00:53:43,130 --> 00:53:43,475
>> [Mwisho avspelning]

1215
00:53:43,475 --> 00:53:44,830
>> DAVID J. Malan: Hiyo ni kwa CS50.

1216
00:53:44,830 --> 00:53:46,246
Shukrani kwa Profesa Nick Parlante.

1217
00:53:46,246 --> 00:53:47,730
Tutaweza kuona wewe wiki ijayo.

1218
00:53:47,730 --> 00:53:51,706

1219
00:53:51,706 --> 00:53:56,435
>> [ELECTRONIC Music kucheza]

1220
00:53:56,435 --> 00:57:22,775