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DOUG LLOYD: Hivyo kama wewe wameweza
kuonekana video wetu juu ya miundo,

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tayari kujua kwamba tuna
uwezo wa kufafanua aina yetu wenyewe data.

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Lakini kama wameweza miundo kutumika, unajua
kwamba wakati mwingine kutumia wale aina ya data

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kweli anaweza kuwa ni kidogo
mbaya kwa sababu sisi

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una kutumia struct keyword
wakati sisi ni kufanya kazi na them--

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struct gari au struct mwanafunzi.

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Kwamba mengi ya aina
kama sisi tu wanataka kuwa na

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kitu rahisi, kama muundo.

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Tunataka have-- tunataka
kuwa na uwezo wa kufanya kazi na mambo

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zaidi kidogo shorthand njia,
kama int au Char, kitu mengi

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rahisi zaidi kwa aina.

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>> Kwa bahati nzuri, kuna
njia ya kufanya hivyo katika C,

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na kitu kinachoitwa typedef, ambayo ni
njia ya kujenga shorthand au kuandikwa upya

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majina ya aina ya data.

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Unaweza kuandika upya data
aina ambazo tayari zipo,

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au unaweza kuandika aina data yako mwenyewe.

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>> Jambo la kwanza kufanya ni wewe
kufafanua aina katika njia ya kawaida,

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na kisha wewe tu vinginevyo hayo kwa kitu
else-- typedef jina la zamani jina jipya.

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Pretty moja kwa moja, sawa?

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Hivyo tunaweza typedef kwa mfano,
data zilizopo tayari

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aina ya unsigned Char kama Byte.

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Na kisha, kuanzia sasa, baada tumekuwa
alifanya aina hii definition-- tena,

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ambayo ni kawaida kwenda kuwa juu
ya nukta yetu mafaili C, au katika nukta H faili

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tofauti, tunaweza tu
kutumia kuuma kila mahali

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tunataka wametumia unsigned Char.

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Hiyo ni mengi mfupi na aina.

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>> Katika maktaba CS50, sisi kufanya Haya
sisi typedef nyota Char kama kamba.

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Kwa sababu sisi yanayotumika
mbali wazo la kuyatumia.

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Na ukweli kwamba kamba ni kweli
pointer character-- kwanza

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safu ya wahusika,
kwa sababu ni tu

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hivyo utata kupata kichwa yako karibu
that-- lakini kwa kweli hiyo ni nini cha kufanya.

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Na mstari wa kanuni kweli lipo
katika CS50 nukta H typedef Char kamba nyota,

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tu kufanya kwamba kidogo kidogo
mbaya kwa kuwa na kushughulika na.

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Tayari wameweza kuona pengine
kidogo ya thamani hapa,

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lakini typedef inakuwa kubwa
wakati pamoja na miundo,

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kama mimi alluded mapema.

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Miundo na mbili neno aina jina.

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Na ili waweze kuwa kweli annoying
kujenga vigezo ya aina hiyo,

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au [inaudible] ya struct kitu, yako
mistari unaweza tu kupata kweli, kweli kwa muda mrefu.

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Na hivyo unaweza kutumia typedef kuja
na kitu mengi mfupi.

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>> Hivyo kama mimi kufafanua gari kama ifuatavyo, nina
tafsiri yangu ya car-- struct gari,

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na kisha kufungua curly brace, kila
mashamba ya muundo yangu,

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karibu curly brace, nusu colon--
baada nimekuwa inavyoelezwa aina yangu data,

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Siwezi typedef struct
gari kama gari kusisitiza t.

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Na kisha wakati mimi tumefanya kwamba, sasa kila
wakati mimi ingekuwa vinginevyo kutumika struct

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gari, naweza tu kutumia gari kusisitiza t.

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Kwamba mengi mfupi wa njia ya
kueleza wazo hili la mfumo huu

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kwamba mimi tu kuundwa.

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>> Vinginevyo, kwa sababu miundo
ni hivyo kawaida kutumika katika typedef,

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kuna a-- unaweza kweli kufafanua
aina katika kati ya mwanzo na mwisho.

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Hivyo muundo wa typedef tena ni
Kwa kawaida typedef, jina la zamani, jina jipya,

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ambapo majina tayari
aina kwamba umeunda.

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Lakini unaweza kweli kufafanua muundo
haki ya katikati ya typedef

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badala ya kuwa na kufafanua
ni tofauti, na kisha

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kufanya typedef yake.

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Na kwamba bila kuangalia kama
Haya typedef struct gari,

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wazi curly brace, mapato yote ya shamba yako
ufafanuzi, karibu curly brace, gari t.

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Hivyo jina la zamani ni mambo ambayo yote katika
nyekundu, wewe ni kufafanua tu muundo

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na kumtaja hiyo kwa wakati huo.

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Na kisha jina jipya
ni gari kusisitiza t.

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Na hivyo kama sisi kuanza kutumia
hii katika kanuni, awali mimi

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anaweza kuwa alisema, struct
gari MyCar nusu ya matumbo.

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Vizuri sina kufanya hivyo tena.

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Sasa kwa kuwa nimekuwa kutumika typedef, mimi
unaweza tu kusema gari kusisitiza t, MyCar.

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Kwamba mengi mfupi wa njia
kufanya hivyo, na kwa kweli, ni

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kwenda kuwa mengi zaidi
rahisi, hasa

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kama wewe kuanza kutumia miundo
mengi zaidi katika kanuni yako.

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>> Mimi nina Doug Lloyd.

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Hii ni CS50.

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