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>> [Music kucheza]

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>> DOUG LLOYD: Sawa.

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Tumekuwa kazi na integers,
tumekuwa kazi na wahusika,

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tumekuwa kazi ikifungwa,
mara mbili, masharti, na bools.

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Tumekuwa nimechoka pretty much wote
ya [inaudible] aina kwamba

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wamekuwa inapatikana kwa sisi wote pamoja.

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Lakini sasa tunataka kufanya kitu zaidi.

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Je, sisi kufanya hivyo?

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Je, sisi kuunda aina tofauti data?

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Tunaweza kufanya hivyo kwa kutumia miundo.

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Hivyo miundo kuruhusu sisi kuunganisha
vigezo ya aina tofauti

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katika moja, mpya kutofautiana aina,
ambayo tunaweza kuwapa aina ya jina lake mwenyewe.

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Hii ni kweli nguvu
Jambo kuwa na uwezo wa kufanya,

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kwa sababu tunaweza sasa kundi
mambo ya aina mbalimbali data

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pamoja kwamba kuwa na uhusiano mantiki.

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Tumekuwa na uwezo wa kufanya hivyo
na arrays aina ya, haki?

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Tunaweza kundi vigezo
ya data aina moja

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pamoja katika kitengo kubwa
ya kumbukumbu, safu.

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>> Lakini sisi hawajaweza kuchanganya
up data aina tofauti pamoja.

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Hatuwezi, kusema, jozi integer,
na tabia, na mara mbili zote

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katika kitu kimoja na
wito kwamba kitengo moja.

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Lakini pamoja na miundo, au
mara nyingi hujulikana kama structs,

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sisi kweli anaweza.

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Hivyo muundo ni aina
ya kama kutofautiana super.

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Ni kutofautiana kwamba ina
vigezo vingine ndani yake.

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Hivyo hapa ni mfano wa
muundo rahisi sana.

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Hii ni nini syntax bila kuangalia
kama kujenga muundo kwa ajili ya gari.

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Sasa, hebu kwenda kwa njia ya syntax hapa.

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Struct, hiyo ni
Keyword kwamba inaonyesha

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kwamba mimi nina kujenga aina mpya data hapa.

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Hasa, jina data aina ni
kwenda kuwa struct gari, kama tutaweza kuona.

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Lakini hii ni aina ya ncha
mbali na mkusanyaji kwamba hii

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kama kundi la vigezo kwamba ni kwenda
kuchukuliwa sehemu ya aina moja

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katika dakika.

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>> Magari, tu jina ya muundo.

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Tena, aina data hapa ni kwenda
kuwa struct gari, si tu gari.

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Lakini kama una different--
kama kujenga structs nyingi

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katika mpango huo, unahitaji
kutofautisha kati ya struct na struct.

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Hivyo struct gari, mimi mwenyewe ninazo sababu
struct mwanafunzi, kwa mfano,

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katika mpango huo.

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Ndani ya braces curly ni
wote wa kinachojulikana mashamba,

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au wanachama wa muundo.

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Kwa hiyo kile ni baadhi ya mambo
ambayo ni asili katika gari?

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Naam, ni kawaida ina mwaka, ina
jina mfano, na sahani leseni,

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odometer kwamba kwa kawaida ina
baadhi ya idadi ya maili juu yake,

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na labda ukubwa wa injini.

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Na kama unaweza kuona, mimi nina kuchanganya juu
integers na wahusika na mara mbili.

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Wao ni wote kwenda kuwa
sehemu ya huu mpya aina data.

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>> Mwisho, jambo la mwisho mimi haja ya kufanya,
usisahau huu semicolon kidogo

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mwishoni.

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Baada ya sisi kumaliza kufafanua muundo,
tunahitaji kuweka semicolon mwishoni.

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Ni kawaida sana syntactical
makosa, kwa sababu kwa kazi,

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Kwa mfano, ungekuwa tu na
wazi curly brace, karibu curly brace.

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Huwezi kuweka semicolon katika
Mwishoni mwa kazi ufafanuzi.

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Hii inaonekana kama kazi
ufafanuzi, lakini siyo,

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na hivyo semicolon huko
ni tu kukumbusha kuwa wewe

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haja ya kuiweka huko, kwa sababu
compiler mapenzi vinginevyo si

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kujua nini cha kufanya na hayo.

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Ni kosa la kawaida sana
kwa ajali kufanya

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wakati wewe ni kwanza kufafanua miundo.

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>> SAWA.

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Hivyo sisi kwa kawaida kufafanua miundo yetu
katika sana juu ya mipango yetu

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kwa sababu wao ni pengine ni kwenda
kutumiwa na kazi nyingi.

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Hatutaki kufafanua
struct ndani ya kazi,

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kwa sababu basi tunaweza only--
wigo wa mfumo wa kweli

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tu ipo ndani ya kazi hiyo.

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Tunatarajia pengine wanataka kufafanua muundo
ili tuweze kutumia katika kazi nyingi,

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au labda katika mbalimbali
mafaili ambayo ni amefungwa pamoja

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kujenga mpango wetu moja.

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Wakati mwingine pia badala
ya kufafanua muundo

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juu sana ambapo wewe kuweka yako
chupa pamoja na na chupa yako amefafanua,

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kwa mfano, unaweza kuziweka katika
tofauti mafaili nukta h, ambayo wewe kisha

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chupa ni pamoja na wewe mwenyewe.

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>> Hivyo tuna miundo, lakini sasa
tunahitaji kupata ndani mwao.

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Je, sisi kupata ndani ya
muundo wa upatikanaji

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wale ndogo vigezo, vigezo wale
ambazo zipo ndani ya mfumo wa?

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Naam, tuna kitu kinachoitwa
dot operator, ambayo inaruhusu sisi

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kupata mashamba ya muundo.

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Hivyo kwa mfano, hebu sema nimekuwa alitangaza
data zangu muundo aina fulani

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juu ya mpango wangu, au labda katika
dot h faili kwamba nimepata chupa pamoja.

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Kama mimi basi unataka kujenga mpya
kutofautiana wa aina hiyo data, naweza kusema,

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struct gari, gari langu, semicolon.

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Tu kama mimi naweza kusema int
x, au kamba jina semicolon.

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>> Aina ya data hapa ni struct gari,
jina la kutofautiana ni gari langu,

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na kisha naweza kutumia nukta operator kwa
kupata maeneo mbalimbali ya gari langu.

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Hivyo naweza kusema gari langu
dot mwaka ni sawa na 2011.

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Hiyo ni kikamilifu faini.

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Mwaka, kama unakumbuka, ilipewa kama
integer uwanja ndani ya hii gari struct

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Aina ya data.

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Hivyo yoyote kutofautiana wa data struct gari
aina, kama vile gari langu, naweza kusema gari langu

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dot mwaka ni sawa na na kisha kuwapa
ni baadhi ya thamani integer, 2011.

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My gari nukta sahani ni sawa na CS50.

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Kadi nukta yangu odometer
sawa 50,505 semicolon.

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Wote wa wale watu
kikamilifu faini na kwamba

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jinsi sisi kupata
mashamba ya muundo.

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Miundo, ingawa, hawana haja
kutengenezwa juu ya stack.

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Tu kama kutofautiana nyingine yoyote, sisi
Unaweza dynamically kutenga yao.

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Kama tuna mpango kwamba huenda
kuwa kuzalisha miundo wengi,

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hatujui ni wangapi
sisi ni kwenda haja,

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basi tunahitaji dynamically
kutenga miundo hiyo

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kama mpango wetu ni mbio.

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Na hivyo kama tunakwenda kupata
mashamba ya muundo katika mazingira ya hapo,

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kukumbuka kwamba tunahitaji kwanza dereference
pointer muundo,

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na kisha mara moja sisi dereference
pointer, kisha tuweze kupata mashamba.

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Kama sisi tu
pointer kwa muundo,

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hatuwezi tu kusema pointer dot shamba
jina na kupata kile sisi ni kuangalia kwa.

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Kuna hatua za ziada ya dereferencing.

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Basi hebu kusema kwamba
badala ya previous--

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kama mfano uliopita,
badala ya kutangaza ni

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juu ya stack, struct gari, yangu
gari, semicolon, nasema struct gari,

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nyota, pointer
struct gari aitwaye gari langu,

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sawa malloc ukubwa wa struct gari.

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Ukubwa wa tutaweza kufikiri jinsi wengi
ka mpya aina yako data unachukua.

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Wewe si lazima tu haja ya kutumia
ukubwa wa, upana, int, au Char, au yoyote

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ya kujengwa katika aina ya data.

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Compiler ni smart kutosha
kufikiri ka wangapi

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wanatakiwa na muundo yako mpya.

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Hivyo mimi malloc mwenyewe kitengo cha kumbukumbu
kubwa ya kutosha kushikilia struct gari,

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na mimi kupata pointer nyuma
kwa kuwa block ya kumbukumbu,

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na kwamba pointer ni kwa ajili ya gari langu.

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>> Sasa, kama nataka kupata
mashamba ya gari langu,

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Mimi kwanza dereference gari langu kwa kutumia
dereference operator, nyota

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kwamba tumeona kutoka kuyatumia
video, na kisha baada ya mimi dereference,

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kisha naweza kutumia nukta operator kwa
kupata maeneo mbalimbali ya gari langu.

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Nyota gari langu nukta mwaka ni sawa na 2011.

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Ambalo litakuwa na athari
tunataka katika kesi hii,

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kwa sababu tumekuwa dynamically
zilizotengwa gari langu.

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>> Hiyo ni aina ya annoying, ingawa, sawa?

130
00:06:43,610 --> 00:06:44,818
Kuna mchakato wa hatua 2 sasa.

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Sasa tuna dereference--
tuna nyota operator,

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na tuna nukta operator.

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Na kama unaweza kutarajia, kwa sababu
C programmers upendo njia fupi

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kufanya mambo, kuna
njia fupi kwa kufanya hivyo.

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Kuna operator mwingine aitwaye mshale,
ambayo inafanya mchakato huu rahisi sana.

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Njia mshale kazi ni
kwanza dereferences

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pointer upande wa kushoto
upande wa operator,

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na kisha, baada ya dereferenced
pointer upande wa kushoto,

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ni wanapata uwanja juu ya haki.

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Na hivyo awali tulikuwa na aina hii
ya nyota gari langu dot mambo haya yote,

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kama kuna mengi kinachoendelea huko.

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Lakini nini tunaweza badala kufanya ni Haya
gari mshale wangu mwaka ni sawa na 2011.

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>> Tena nini kinatokea hapa?

144
00:07:23,580 --> 00:07:25,720
Kwanza, mimi nina dereferencing gari langu.

145
00:07:25,720 --> 00:07:27,810
Ambayo tena, ni pointer hapa.

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Kisha, baada ya
dereferenced gari langu, mimi

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Basi unaweza kupata mashamba
mwaka, sahani, na odometer

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tu kama mimi naweza kabla ya kuwa na kwanza
kutumika nyota dereference gari langu,

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na nukta ya kupata shamba.

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Hivyo unaweza kuwa na miundo, wewe
unaweza kuwa na kuyatumia kwa miundo,

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na una njia za upatikanaji
mashamba ya miundo hiyo,

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00:07:48,360 --> 00:07:52,600
kama una kuyatumia kwa
nao au vigezo wenyewe.

153
00:07:52,600 --> 00:07:57,640
Dot au mshale, kutegemea
jinsi kutofautiana ilitangazwa.

154
00:07:57,640 --> 00:08:00,510
Mimi nina Doug Lloyd, hii ni CS50.

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