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>> [Halisi kucheza]

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>> DAVID J. Malan: zote haki hii ni CS50
na hii ni mwanzo wa wiki tano.

3
00:00:16,630 --> 00:00:21,480
Hivyo leo, chini ya kiti yako matakia,
huwezi kupata kitu chochote.

4
00:00:21,480 --> 00:00:24,790
Lakini juu, unapaswa kupata hizi,
kidogo ishara ya shukrani yetu kwa ajili ya

5
00:00:24,790 --> 00:00:26,970
yote ya kazi kwamba kuweka
katika mchezo wa kumi na tano.

6
00:00:26,970 --> 00:00:30,290
Tu kuondoa mzunguko kidogo juu ya
chini na kuanza kucheza kwa

7
00:00:30,290 --> 00:00:31,680
salio ya darasa.

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00:00:31,680 --> 00:00:38,930
>> Hivyo kukumbuka kwamba, au kujua kwamba tatizo kuweka
nne, ambayo akatoka mwishoni mwa wiki hii,

9
00:00:38,930 --> 00:00:40,340
inahusisha kuandika mchezo mwingine.

10
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Lakini wakati huu inahusisha kutumia
halisi graphical user interface, si

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00:00:43,740 --> 00:00:46,310
textual interface kama
Mchezo wa kumi na tano ilikuwa.

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00:00:46,310 --> 00:00:50,210
Na mchezo kwamba liko mbele yenu,
kama wameweza bado kuonekana hii ya pili,

13
00:00:50,210 --> 00:00:52,310
inaonekana kitu kidogo kama hii.

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00:00:52,310 --> 00:00:55,170
Mimi nina kwenda katika terminal yangu
dirisha hapa katika GDB.

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00:00:55,170 --> 00:00:58,600
Na mimi nina kwenda mbele na kukimbia
wafanyakazi ufumbuzi, ambayo unaweza kupata

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00:00:58,600 --> 00:01:01,010
baada ya mbio update 50 kama kawaida.

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00:01:01,010 --> 00:01:04,090
>> Lakini mimi nina kwenda kuiweka katika kidogo
siri mode, kidogo Pasaka yai,

18
00:01:04,090 --> 00:01:08,480
kinachojulikana Mungu mode, na
kuweka Mungu katika argv1.

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00:01:08,480 --> 00:01:12,920
Na mimi na kufuata maelekezo yangu mwenyewe,
mbio katika yangu mwenyewe

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00:01:12,920 --> 00:01:14,220
tatizo kuweka directory.

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Hivyo sasa unaweza kuona toleo kamili
ya mchezo wa kuzuka.

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Kwa kweli, hii ni hakuna mikono mode.

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Hivyo ni kweli -

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wowed ingawa unaweza kuwa -

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pretty yasiyo na maana ya kutekeleza Mungu mode katika
Kuzuka, tofauti na mchezo wa kumi na tano,

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ambayo baadhi yenu wanaweza kuwa na kukabiliana
kwa ajili ya toleo hacker.

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>> Katika kuzuka Inatosha katika Mungu
mode tu kufanya nini,

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shirikishi na paddle?

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Tu kufanya hivyo sawa na chochote
nafasi ya usawa ni ya mpira.

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Na muda mrefu kama wewe kufanya hili katika lockstep
na mpira kusonga mchezo huu mapenzi

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kamwe, daima, milele miss ya mpira
na utasikia kushinda kila wakati.

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>> Lakini katika hacker toleo la wiki hii
kuna zaidi kuliko tu mode Mungu.

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Kuna idadi ya makala mengine.

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Kati yao, lasers.

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Ili kwamba kama wewe kweli kupata papara wewe
unaweza kuanza risasi chini matofali

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na wengine wachache.

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Na kwa wale ambao Ningependa
calibrate kiwango dhidi hacker

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00:02:04,560 --> 00:02:08,750
toleo, naona ya kuwa wiki hii
hacker toleo makusudi ni

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zaidi kidogo doable, kusema, zaidi ya Mungu
mode alikuwa pamoja na michezo ya kumi na tano.

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>> Hivyo kama wewe ni kuangalia kwa kunyoosha na
wewe ni kuangalia kwa ajili ya kujifurahisha baadhi ya ziada

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makala kufanya dive katika kama ya riba.

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Sasa zaidi kivitendo, napenda uhakika
nje jambo moja pia.

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GDB, ambayo baadhi yenu wanaweza kuwa bado
kuguswa binafsi, ambayo ni nzuri.

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Lakini sasa ni kweli muda wa kupata kutumika
kwa hii na starehe na chombo hiki

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sababu itakuwa kufanya maisha yako
rahisi sana, kwa kweli.

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>> Kwa hotuba Rob juu GDB wanandoa
ya wiki iliyopita, kukumbuka

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GDB kwamba ni debugger.

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Ni chombo kwamba inakuwezesha kuendesha yako
mpango lakini kukimbia hivyo hatua kwa hatua ya mstari,

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na mstari, ili uweze poke kote,
Basi utaona mambo yanayotokea, hivyo

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kwamba unaweza magazeti nje
maadili ya vigezo.

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Kwa kifupi, inakupa hivyo zaidi
nguvu zaidi kuliko printDef gani.

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>> Sasa admittedly, interface
ni pretty arcane.

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Nyeusi na nyeupe textual interface
kwa sehemu kubwa.

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amri ni kiasi fulani mgumu
kukumbuka mara ya kwanza.

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Lakini hata ingawa inaweza kuchukua wewe nusu
Saa, saa, ili kuweka kwamba upfront

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00:03:01,230 --> 00:03:02,940
uwekezaji wa muda ndani yake, imani yangu.

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Hakika na mwisho wa muhula wa itakuwa kuokoa
wewe utaratibu wa ukubwa zaidi

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muda zaidi ya hiyo.

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>> Hivyo mapema katika dive wiki in

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Na katika suala la kuzuka, tunajua kwamba wewe
anaweza kufanya hili kwa muda mrefu kama una

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kanuni ya usambazaji au kanuni yako mwenyewe
katika maendeleo katika saraka yako Pst4.

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Kujua kwamba unaweza kuendesha GDB / kuzuka..

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>> Hii ni kwenda kufungua
dirisha kama hii.

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Napenda kutoa mwenyewe zaidi
ya dirisha terminal.

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Na kisha nini mimi kwenda mbele
na kufanya, siyo tu kukimbia.

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Mimi nina kwenda kwanza kuweka hatua ya mapumziko
kukumbuka, ambayo inaruhusu pause

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utekelezaji katika mahali fulani.

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>> Tu kuweka mambo rahisi mimi naenda
kuvunja katika mstari mmoja tu kwa kuchapa

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namba moja.

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Hebu kweli re-wazi dirisha hili
kwa sababu ni kupata

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kidogo kidogo huko.

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Hivyo nini mimi sasa kwenda kufanya hapa ni
kama mimi kufungua terminal yangu dirisha.

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Haya, kuna sisi kwenda.

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>> Hivyo sasa kama mimi kurejea dropbox, Pst4
na kukimbia GDB. / kuzuka kuingia, taarifa

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Mimi nina kwenda kuvunja moja ya kuweka
hatua ya mapumziko katika mstari mmoja.

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Na sasa mimi nina kwenda
mbele na aina kukimbia.

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00:04:04,840 --> 00:04:07,370
Na wakati mimi kufanya, taarifa chochote
inaonekana kutokea.

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>> Hakuna hadi pop.

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Hakuna grafiki
user interface bado.

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Lakini hiyo ni kueleweka kwa sababu mimi nina
halisi katika mstari mmoja katika mpango wangu.

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Na taarifa kwamba nimepata haraka kupelekwa,
hasa sasa hadi 62, kwa sababu kila

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mambo ya wakati juu ya faili hii ni
mambo kama maoni na constants na

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uninteresting mambo kwa sasa.

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>> Hivyo sasa mimi nina ndani ya kuu,
inaonekana, katika mstari wa 62.

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Na hii ni usambazaji
kanuni, kukumbuka.

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Kama mimi kufungua hili kwa kwenda, vile vile,
ndani ya tone yangu sanduku directory katika Pst4,

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katika breakout.c.

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Na kama mimi kitabu chini na chini na chini,
na napenda kwenda mbele na kurejea kwenye

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line yangu namba.

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>> Nini mimi utaona, kama mimi kitabu chini ya
mstari 62, ni hasa mstari kwamba

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tumekuwa paused juu.

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Hivyo mstari huu hapa, 62, ni
ambapo sisi ni juu ya kuwa.

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Hivyo sasa katika GDB, kama mimi kwenda mbele na aina
sasa ijayo, kuingia itakavyo

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nitafanya kuwa mstari.

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Na voilà, tuna
kinachojulikana g dirisha.

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Kama usio wa kawaida na kile GWindow
ni, si kuwa na wasiwasi.

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spec kuanzisha wewe kwa hiyo, kama
vile idadi ya video walkthrough

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iliyoingia katika spec.

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>> Lakini sasa hebu kufanya hii
kidogo zaidi ya kuvutia.

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Hebu hoja hii dirisha juu ya
kwa upande kidogo.

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Napenda kufanya dirisha kidogo
kubwa hivyo siwezi kuona zaidi.

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>> Na sasa napenda kwenda mbele
na kufanya ijayo tena.

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Na kuna matofali yangu.

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Kama mimi aina ijayo tena
sasa naona mpira.

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Na kama mimi aina ijayo tena
sasa naona paddle.

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>> Na kwa bahati nzuri gedit hii si
kweli kushirikiana kwa kunionyeshea

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kila kitu nataka.

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Lakini sasa kama mimi kufanya ijayo tena,
ijayo tena, Mimi tu

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kutangaza baadhi ya vigezo.

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Na mimi unaweza magazeti yeyote
ya haya guys nje.

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Magazeti matofali, prints maisha.

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>> Na sasa kama mimi kuendelea kufanya
pili, taarifa kwamba mimi itakuwa

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ndani ya kitanzi kwamba.

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Lakini kanuni ni kwenda kutekeleza
hasa kama mimi kutarajia.

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Hivyo wakati mimi hit kazi hii, Subiri
kwa Click, ni kwenda kufanya

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ni halisi kwamba.

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Hivyo mimi walionekana wamepoteza kudhibiti
juu ya mpango.

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>> GDB si kutoa yangu mwingine wa haraka.

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Lakini si kuwa na wasiwasi.

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Kwenda kwa mchezo wangu, bonyeza mahali fulani.

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>> Na voilà, sasa ni kuendelea kwa line ya 86.

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Hivyo tena, ni mchango mkubwa sana, hatimaye,
kwa debugging matatizo.

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Kwa sababu unaweza literally hatua kupitia
kanuni yako, magazeti mambo ya nje na kiasi,

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kiasi, zaidi.

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Lakini kwa sasa, wale zana peke yake
lazima kupata pretty mbali.

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>> Hivyo sisi ni, bila shaka, kuchukua kuangalia
saa Graphics sasa, kwa ghafla.

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Na sasa dunia yetu anapata kidogo
ya kuvutia zaidi.

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Na unajua, pengine, kutoka kwa baadhi ya
videos online kwamba tuna hizi

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kaptula kwamba tumekuwa kuangalia
kama sehemu ya seti tatizo.

131
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>> Na wao tumekuwa risasi, kwa makusudi,
dhidi ya kuongezeka nyeupe.

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Na baadhi yao kuwa na mafundisho
Wenzake kuchora baadhi ya maandishi juu ya

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screen hiyo akaifunika
upande wao.

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Lakini bila shaka, hii si yote ambayo
kuvutia katika ulimwengu wa kweli.

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Hii ni ukumbi wa mihadhara wenye
kubwa nyeupe screen na kuongezeka.

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Na uzalishaji wetu wa ajabu timu aina
wa hufanya kila kitu kuangalia nzuri

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baada ya ukweli na mseto nje
au vichwa kitu

138
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sisi kufanya au hawataki.

139
00:06:37,840 --> 00:06:41,560
>> Sasa tu kuwahamasisha wiki hii na
kweli, ambapo unaweza kwenda, hatimaye,

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na sayansi ya kompyuta.

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Si tu baada ya tatizo kuweka nne.

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Lakini baada ya mwingine bila shaka au mzima
mtaala ni ajabu nini unaweza

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kufanya siku hizi katika suala la
graphics hasa.

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>> Baadhi yenu wanaweza kuona hii
inapita karibu online.

145
00:06:53,440 --> 00:06:56,240
Lakini nilifikiri Ningependa kuonyesha wewe, kwa ajili tu ya
dakika kadhaa, mtazamo wa kile

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00:06:56,240 --> 00:07:01,890
teknolojia ya kompyuta na nini CGI,
graphics kompyuta wanaweza kufanya siku hizi

147
00:07:01,890 --> 00:07:04,510
na wimbo ukoo
na labda movie.

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00:07:04,510 --> 00:07:05,760
>> [MUSIC - Lana Del RAY,
"VIJANA NA BEAUTIFUL]

149
00:07:05,760 --> 00:10:50,270

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>> SPIKA 1: Ni kidogo tu
ajabu, pengine, tu jinsi

151
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omnipresent -

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00:10:52,857 --> 00:10:57,040
>> [Makofi]

153
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>> SPIKA 1: Mimi tu kupakuliwa.

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Lakini ni kweli kushangaza, nadhani, tu
jinsi omnipresent programu na kanuni na

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zana kama kweli hii ni.

156
00:11:04,230 --> 00:11:07,685
Hivyo kwamba ni ladha ya mwelekeo
ambayo unaweza kwenda.

157
00:11:07,685 --> 00:11:10,620
Oh, hakuna Appliance zaidi leo.

158
00:11:10,620 --> 00:11:14,640
Naam, hiyo ni kweli kutisha majira
kupewa uhakika Mimi tu walijaribu kufanya.

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00:11:14,640 --> 00:11:18,670
>> Haki ya wote, hivyo hebu kuzindua
Fusion tena.

160
00:11:18,670 --> 00:11:20,800
Unikumbushe baadaye.

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00:11:20,800 --> 00:11:24,190
Haki zote, na unapaswa kuwa got
email kama kando kama alivyofanya kupata

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00:11:24,190 --> 00:11:25,460
taarifa kama hiyo.

163
00:11:25,460 --> 00:11:29,940
Haki ya wote, hivyo kukumbuka kwamba wiki iliyopita
sisi kuanza peel nyuma hii

164
00:11:29,940 --> 00:11:31,380
baadaye inayojulikana kama kamba.

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00:11:31,380 --> 00:11:34,700
>> kamba anakumbuka data aina hiyo ni
alitangaza katika maktaba CS50.

166
00:11:34,700 --> 00:11:37,740
Na ni sehemu ya magurudumu mafunzo
ambayo sasa kuanza kuchukua mbali.

167
00:11:37,740 --> 00:11:41,280
Ilikuwa ni dhana muhimu mapema.

168
00:11:41,280 --> 00:11:43,750
Lakini sasa ni kwenda kupata zaidi
kuvutia na yenye nguvu zaidi ili

169
00:11:43,750 --> 00:11:48,330
kweli kuona kwamba chini ya Hood,
kamba ni kile tu, je, sisi alisema?

170
00:11:48,330 --> 00:11:50,500
>> Yeah, hivyo ni kinachojulikana Char *.

171
00:11:50,500 --> 00:11:53,860
Na * kuna inaashiria kwamba kuna
baadhi ya aina ya anuani ya kushiriki.

172
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Na hivyo wakati wewe kusema * Char wewe tu maana
kutofautiana ambao data aina ni

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pointer sasa.

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00:11:59,290 --> 00:12:01,770
ukweli kwamba kuna nyota kuna
tu ina maana kwamba wewe ni kutangaza

175
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kinachojulikana pointer.

176
00:12:03,020 --> 00:12:06,220
Na pointer kwamba ni kwenda inaonekana
kuhifadhi anwani ya, ya

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00:12:06,220 --> 00:12:07,810
Bila shaka, char.

178
00:12:07,810 --> 00:12:08,960
>> Sasa kwa nini hii mantiki?

179
00:12:08,960 --> 00:12:11,200
Naam, kile ni kamba
chini ya Hood?

180
00:12:11,200 --> 00:12:15,130
Naam, kwa baadhi ya wakati tumekuwa akisema
kwamba string chini ya Hood ni

181
00:12:15,130 --> 00:12:18,460
tu h-e-l-l-o, kwa mfano.

182
00:12:18,460 --> 00:12:21,585
>> Lakini tumekuwa kuongelea hili kama
kuwa, kimsingi, safu.

183
00:12:21,585 --> 00:12:25,410
Na safu ingekuwa basi kuangalia kidogo
zaidi kama hii, na kila moja ya haya

184
00:12:25,410 --> 00:12:26,460
kuchukua bite.

185
00:12:26,460 --> 00:12:28,710
Na kisha tumekuwa alisema kwamba kuna
kitu maalum nyuma hapa,

186
00:12:28,710 --> 00:12:31,270
backslash 0, au null Terminator.

187
00:12:31,270 --> 00:12:35,230
>> Hivyo muda wote huu, hii hapa
imekuwa kamba.

188
00:12:35,230 --> 00:12:38,320
Lakini kwa kweli, kamba ni
kweli anwani.

189
00:12:38,320 --> 00:12:43,210
Na anwani, kama tutaweza kuona, ni mara nyingi
prefixed na 0x na mkataba.

190
00:12:43,210 --> 00:12:44,540
Je 0x kuashiria?

191
00:12:44,540 --> 00:12:45,970
Je, mtu yeyote kujua?

192
00:12:45,970 --> 00:12:47,320
>> Hivyo ni njia tu hexadesimoli.

193
00:12:47,320 --> 00:12:52,360
Hivyo unaweza kukumbuka, kwa kweli, kutoka PST
1, naamini, moja ya joto-up

194
00:12:52,360 --> 00:12:55,740
maswali ya kweli kuulizwa kuhusu
hexadesimoli nukuu kwa kuongeza

195
00:12:55,740 --> 00:12:57,100
binary na decimal.

196
00:12:57,100 --> 00:13:00,460
Na motisha hapa ni kwamba
na hexadesimoli una 16

197
00:13:00,460 --> 00:13:01,770
maadili ovyo wako.

198
00:13:01,770 --> 00:13:07,900
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ikifuatiwa
na, b, c, d, e, f.

199
00:13:07,900 --> 00:13:10,430
>> Na kama wewe kuhesabu hadi wale wote,
kupata jumla ya 16.

200
00:13:10,430 --> 00:13:13,200
Hivyo hii ni tofauti na
decimal, ambapo tuna 10

201
00:13:13,200 --> 00:13:14,690
maadili, 0 kupitia tisa.

202
00:13:14,690 --> 00:13:17,750
Ni tofauti na kisha
ambapo sisi tu 0 na 1.

203
00:13:17,750 --> 00:13:21,450
>> Lakini mwisho wa siku unaweza tu
kuwakilisha nambari moja, lakini

204
00:13:21,450 --> 00:13:22,500
kwa njia tofauti.

205
00:13:22,500 --> 00:13:25,840
Na hexadesimoli ni ya kawaida kwa sababu kama
zinageuka - na tutaweza kuona hii

206
00:13:25,840 --> 00:13:28,790
baadaye katika shaka - hata wakati sisi kupata
na mtandao wa programu katika mazingira ya

207
00:13:28,790 --> 00:13:32,100
HTML na namba ya Michezo,
hexadesimoli ni nzuri.

208
00:13:32,100 --> 00:13:36,390
Kwa sababu kila tarakimu, zamu nje,
inawakilisha bits wanne kikamilifu.

209
00:13:36,390 --> 00:13:39,280
Hivyo ni aina tu ya mistari up nicely
kama tutaweza hatimaye kuona.

210
00:13:39,280 --> 00:13:44,720
Hivyo hii inaweza kuwa Ox123 au kitu
kama kwamba, denoting anuani 123

211
00:13:44,720 --> 00:13:47,050
mahali fulani ndani ya yangu
kompyuta kumbukumbu.

212
00:13:47,050 --> 00:13:50,600
>> Lakini bila shaka, baadhi ya matatizo yanajitokeza
sababu ya hii msingi

213
00:13:50,600 --> 00:13:51,520
utekelezaji.

214
00:13:51,520 --> 00:13:55,930
Na kukumbuka kwamba mimi alichukua kumchoma katika
utekelezaji wa kazi kama hii -

215
00:13:55,930 --> 00:14:00,260
kulinganisha dash 0 dot c wiki iliyopita, kwamba
hata kama inaonekana kama ilikuwa

216
00:14:00,260 --> 00:14:04,270
kulia, ni tu hakuwa na kulinganisha
mbili masharti usahihi.

217
00:14:04,270 --> 00:14:07,470
>> Nimekuwa kutupwa mbali kuu, na nimekuwa kutupwa
mbali maoni tu kulenga katika juu ya

218
00:14:07,470 --> 00:14:08,970
kificho kwamba ni wa maslahi hapa.

219
00:14:08,970 --> 00:14:10,660
Na ni katika nyekundu kwa sababu ni Buggy.

220
00:14:10,660 --> 00:14:11,670
Kwa sababu gani?

221
00:14:11,670 --> 00:14:15,890
>> Naam, kuna wakati mimi juu alitangaza
kamba, nini ilikuwa kweli kinachoendelea

222
00:14:15,890 --> 00:14:17,260
chini ya Hood?

223
00:14:17,260 --> 00:14:19,530
Naam, napenda kwenda juu kwa
screen hapa na kuteka kwamba.

224
00:14:19,530 --> 00:14:23,230
Hivyo mimi alitangaza, tena,
kamba s GetString.

225
00:14:23,230 --> 00:14:26,640
>> Hivyo nina kwenda mbele sasa na
kuteka s kwa nini ni kweli ni.

226
00:14:26,640 --> 00:14:28,590
Ni kwenda kuwa mraba hapa.

227
00:14:28,590 --> 00:14:30,490
Na mimi nina kwenda kudai
kwamba hiyo ni 32 bits.

228
00:14:30,490 --> 00:14:32,890
Angalau ni kawaida ni,
angalau juu CS50

229
00:14:32,890 --> 00:14:34,520
appliance katika mengi ya kompyuta.

230
00:14:34,520 --> 00:14:35,980
Mimi nina kwenda kwa simu yake ya.

231
00:14:35,980 --> 00:14:39,070
>> Lakini sasa kukumbuka kuwa sisi
kuitwa GetString.

232
00:14:39,070 --> 00:14:41,430
Hivyo GetString anarudi,
bila shaka, kamba.

233
00:14:41,430 --> 00:14:45,790
Kama aina user katika h-e-l-l-o kuingia
kamba hujambo anapata akarudi.

234
00:14:45,790 --> 00:14:51,010
Na kamba kwamba, kama sisi tu alisema, mwisho
hadi mahali fulani katika kumbukumbu ya kompyuta yako

235
00:14:51,010 --> 00:14:53,240
na 0 backslash mwishoni.

236
00:14:53,240 --> 00:14:56,650
Mimi itabidi kuteka hii kama safu - au
contiguous block ya wahusika -

237
00:14:56,650 --> 00:14:58,330
kwamba ni kweli ni.

238
00:14:58,330 --> 00:15:01,790
>> Na sasa, ni nini GetString
kweli kurudi?

239
00:15:01,790 --> 00:15:04,340
Nini GetString wamekuwa kurudi
yote ya wakati huu?

240
00:15:04,340 --> 00:15:07,520
Naam, sisi kusema, katika wiki kabla,
kuirudisha kamba.

241
00:15:07,520 --> 00:15:10,250
Lakini zaidi ya kitaalam, ni nini
GetString kurudi inaonekana?

242
00:15:10,250 --> 00:15:11,610
>> Watazamaji: anwani.

243
00:15:11,610 --> 00:15:12,600
>> SPIKA 1: anwani.

244
00:15:12,600 --> 00:15:16,630
Hasa kuirudisha anwani ya
bite kwanza kabisa, chochote ni.

245
00:15:16,630 --> 00:15:18,830
Mimi tu kuendelea kutumia moja, mbili, tatu
kwa sababu ni rahisi.

246
00:15:18,830 --> 00:15:21,380
>> Kuirudisha anuani ya kwanza
tabia katika kamba.

247
00:15:21,380 --> 00:15:23,510
Na sisi alisema wiki iliyopita kuwa
kwamba ni wa kutosha.

248
00:15:23,510 --> 00:15:26,710
Kwa sababu tunaweza daima kufikiri ambapo
mwisho wa kamba tu kwa

249
00:15:26,710 --> 00:15:30,150
iterating juu yake, labda, na kwa
kitanzi au kitanzi wakati au kitu kama

250
00:15:30,150 --> 00:15:34,990
kwamba, kuangalia tu kwa "backslash 0",
maalum sentinel tabia.

251
00:15:34,990 --> 00:15:37,220
>> Na kisha sisi kujua kwamba kamba
hutokea kwa kuwa ya urefu -

252
00:15:37,220 --> 00:15:37,980
katika kesi hii -

253
00:15:37,980 --> 00:15:38,670
tano.

254
00:15:38,670 --> 00:15:43,800
Basi kitaalam nini GetString gani
ni kuirudisha Ox123 katika kesi hii.

255
00:15:43,800 --> 00:15:53,670
Na utaalamu nini basi kinachotokea ni
kwamba sisi kuhifadhi, ndani ya s, Ox123.

256
00:15:53,670 --> 00:15:56,460
Mwisho wa siku, hata kama hii
ni dhana mpya, kuyatumia, wao ni

257
00:15:56,460 --> 00:15:57,350
tu vigezo.

258
00:15:57,350 --> 00:16:00,440
Lakini wao kutokea kwa kuhifadhi bits kwamba
pamoja kuwakilisha anwani.

259
00:16:00,440 --> 00:16:03,700
Basi kitaalam yote wao anapata
kuhifadhiwa katika s ni Ox123.

260
00:16:03,700 --> 00:16:04,680
>> Lakini sisi kama binadamu -

261
00:16:04,680 --> 00:16:06,020
ikiwa ni pamoja na kuendelea leo -

262
00:16:06,020 --> 00:16:09,290
ni kweli si kwenda huduma, kwa kawaida,
nini anwani halisi ni

263
00:16:09,290 --> 00:16:10,520
baadhi ya chunk ya kumbukumbu.

264
00:16:10,520 --> 00:16:14,040
Ni tu kwa kiwango cha chini cha kina ili
kuwa kielimu kuvutia.

265
00:16:14,040 --> 00:16:15,440
Hivyo nina kwenda kwa kamba hii.

266
00:16:15,440 --> 00:16:19,810
Na badala yake, zaidi ya kiwango cha juu, tu kusema
kwamba wakati sisi ni kuzungumza juu ya kuyatumia

267
00:16:19,810 --> 00:16:22,170
Mimi naenda tu kuteka zaidi
user-kirafiki mshale kwamba zinaonyesha

268
00:16:22,170 --> 00:16:26,060
huo wazo na ikisiri mbali
maelezo ya yale halisi

269
00:16:26,060 --> 00:16:27,700
anuani ya msingi ni.

270
00:16:27,700 --> 00:16:33,290
>> Sasa kama sisi kurudi nyuma kwa kificho, ni nini
kilichotokea wiki iliyopita kama tuna kamba t

271
00:16:33,290 --> 00:16:34,510
sawa GetString?

272
00:16:34,510 --> 00:16:38,630
Naam, kama mimi tena, aina katika hujambo
wakati huu mimi nina kwenda kupata

273
00:16:38,630 --> 00:16:40,460
mwingine chunk ya kumbukumbu.

274
00:16:40,460 --> 00:16:44,820
h-e-l-l-o backslash 0.

275
00:16:44,820 --> 00:16:48,320
>> Lakini kwa sababu mimi kuitwa GetString
mara ya pili -

276
00:16:48,320 --> 00:16:51,100
na ninajua hii kutoka kuangalia
chanzo kanuni kwa GetString - hata

277
00:16:51,100 --> 00:16:54,350
ingawa ni kubahatisha kwamba hujambo mara
typed katika mara mbili, GetString si

278
00:16:54,350 --> 00:16:55,890
kwenda kujaribu kuongeza
na kuwa na wajanja.

279
00:16:55,890 --> 00:16:58,550
Ni tu kwenda kupata mwingine chunk ya
kumbukumbu kutoka kwa kompyuta, ambayo ni

280
00:16:58,550 --> 00:16:59,640
kwenda kuwa katika anuani mwingine.

281
00:16:59,640 --> 00:17:02,330
Hebu kiholela tu kusema 456.

282
00:17:02,330 --> 00:17:04,079
>> Na kisha nini ni kwenda na kurudi?

283
00:17:04,079 --> 00:17:08,030
Ni kwenda na kurudi 456
na kuhifadhi katika t.

284
00:17:08,030 --> 00:17:12,010
Hivyo kweli ni nini kinachoendelea, juu ya
upande wa mkono wa kushoto ni mimi na mwingine chunk

285
00:17:12,010 --> 00:17:14,260
ya kumbukumbu, 32 bits kawaida.

286
00:17:14,260 --> 00:17:16,720
Na huko ni kwenda Ox456.

287
00:17:16,720 --> 00:17:20,140
Lakini tena, Mimi si nia katika haya
hasa idadi tena.

288
00:17:20,140 --> 00:17:23,069
Mimi tu kwenda abstractly
kuteka ni kama mshale.

289
00:17:23,069 --> 00:17:25,202
>> Hivyo hii ni sasa maelezo mpya.

290
00:17:25,202 --> 00:17:28,735
Lakini ni sawa kamili wazo kwamba
yakitokea wakati huu wote.

291
00:17:28,735 --> 00:17:33,150
Na hivyo sababu basi, kwamba hii ya kwanza
toleo la kulinganisha mara Buggy

292
00:17:33,150 --> 00:17:34,480
wiki ya mwisho ni kwa nini?

293
00:17:34,480 --> 00:17:38,000
Wakati wa kufanya kama s ni sawa sawa na
t ni wewe kweli

294
00:17:38,000 --> 00:17:40,550
chini ya Hood kulinganisha?

295
00:17:40,550 --> 00:17:41,910
>> Wewe ni kulinganisha anwani.

296
00:17:41,910 --> 00:17:47,950
Na tu shirikishi, kwa uwazi, Ox123
si kwenda Ox456 sawa.

297
00:17:47,950 --> 00:17:49,380
Wale idadi, wale bits
ni tu tofauti.

298
00:17:49,380 --> 00:17:53,220
>> Na hivyo mara kwa mara, wiki iliyopita alisema
unapoandika mambo mbalimbali, hata kama

299
00:17:53,220 --> 00:17:55,360
maneno walikuwa verbatim sawa.

300
00:17:55,360 --> 00:17:58,770
Hivyo sisi kurekebisha hii.

301
00:17:58,770 --> 00:18:00,120
Katika suala layman, nini ilikuwa fix?

302
00:18:00,120 --> 00:18:02,110
>> Watazamaji: Matumizi ya kazi.

303
00:18:02,110 --> 00:18:02,870
>> SPIKA 1: Matumizi ya kazi.

304
00:18:02,870 --> 00:18:05,190
Au nyota ni dhahiri wanaohusika,
lakini kutumia kazi ya kufanya nini?

305
00:18:05,190 --> 00:18:05,962
>> Watazamaji: Ili kulinganisha masharti.

306
00:18:05,962 --> 00:18:07,390
>> SPIKA 1: Ili kulinganisha masharti.

307
00:18:07,390 --> 00:18:11,030
Hivyo tatizo la msingi hapa ilikuwa
kwamba nilikuwa tu kuzingatia

308
00:18:11,030 --> 00:18:15,870
ubora wa masharti ya kuelezwa na
kulinganisha ya anwani zao.

309
00:18:15,870 --> 00:18:18,540
Na ni wazi kwamba tu bubu sasa kwa mara nyingine
wewe kuelewa nini kinaendelea

310
00:18:18,540 --> 00:18:19,510
chini ya Hood.

311
00:18:19,510 --> 00:18:23,270
Kwa kweli kulinganisha masharti ili kuona kama
wao ni sawa katika njia ambayo binadamu

312
00:18:23,270 --> 00:18:26,680
bila kuzingatia masharti mbili kuwa sawa
tunahitaji kulinganisha yao tabia kwa

313
00:18:26,680 --> 00:18:28,070
tabia kwa ajili ya tabia.

314
00:18:28,070 --> 00:18:30,020
>> Sasa mimi naweza kuwa na kufanyika
hii sana tediously.

315
00:18:30,020 --> 00:18:32,240
Lakini familiarly, tuko
kutumia kwa kitanzi.

316
00:18:32,240 --> 00:18:36,050
Na tu kulinganisha s bracket
i dhidi ya t mabano i.

317
00:18:36,050 --> 00:18:39,590
s mabano i pamoja na 1 dhidi ya t bracket
i pamoja na 1, na kadhalika, ndani ya

318
00:18:39,590 --> 00:18:40,580
baadhi ya aina ya kitanzi.

319
00:18:40,580 --> 00:18:44,950
Na kama mimi doa wahusika yoyote mbili ambazo
tofauti, au kama mimi kutambua kwamba ooh, s ni

320
00:18:44,950 --> 00:18:48,410
mfupi kuliko t au muda mrefu zaidi ya t
Naweza mara moja kusema uongo,

321
00:18:48,410 --> 00:18:49,390
wao siyo sawa.

322
00:18:49,390 --> 00:18:55,370
>> Lakini kama mimi kupata njia ya s na t na kusema
sawa, sawa, sawa, sawa, sawa, mwisho wa

323
00:18:55,370 --> 00:18:58,520
wote masharti, naweza kusema
kweli, ni sawa.

324
00:18:58,520 --> 00:19:01,040
Naam, nashiriki, miaka iliyopita mtu
aliandika kwamba kanuni kwa ajili yetu.

325
00:19:01,040 --> 00:19:03,790
>> Na wao kuitwa ni StrComp
kwa kamba kulinganisha.

326
00:19:03,790 --> 00:19:11,900
Na hata kama ni kidogo counter
angavu, StrComp anarudi 0 kama wale

327
00:19:11,900 --> 00:19:14,520
mbili masharti, s na t ni sawa.

328
00:19:14,520 --> 00:19:18,090
Lakini kuirudisha thamani hasi kama s
waje mbele t alphabetically au

329
00:19:18,090 --> 00:19:20,610
chanya thamani ikiwa ni lazima kuja
baada ya t alphabetically.

330
00:19:20,610 --> 00:19:24,030
>> Hivyo kama wewe milele unataka kutatua kitu,
zinageuka kuwa StrComp ni muhimu.

331
00:19:24,030 --> 00:19:26,660
Sababu haina tu kusema
ndiyo au hapana, sawa au la.

332
00:19:26,660 --> 00:19:30,440
Ni anakupa hisia ya kuagiza
kama nguvu kamusi.

333
00:19:30,440 --> 00:19:33,770
Hivyo StrComp, s comma t sawa
sawa na njia 0 kwamba

334
00:19:33,770 --> 00:19:35,200
masharti ni kweli sawa.

335
00:19:35,200 --> 00:19:38,680
Kwa sababu mtu aliandika kazi huu
miaka iliyopita labda kutumika kwa kitanzi

336
00:19:38,680 --> 00:19:42,840
au kitanzi wakati au kitu kama hicho
kuunganisha tena juu ya wahusika

337
00:19:42,840 --> 00:19:45,270
na tena na tena.

338
00:19:45,270 --> 00:19:47,300
>> Lakini tatizo mbili akaondoka hapa.

339
00:19:47,300 --> 00:19:48,750
Hii ilikuwa copy0.c.

340
00:19:48,750 --> 00:19:51,680
Na mbili katika nyekundu ni
sababu ni kiujanja.

341
00:19:51,680 --> 00:19:52,800
Na nini sisi kufanya hapa?

342
00:19:52,800 --> 00:19:54,310
Naam, kwanza mimi kuitwa GetString.

343
00:19:54,310 --> 00:19:56,255
Na mimi kuhifadhiwa thamani ya kurudi katika s.

344
00:19:56,255 --> 00:20:00,260
Hivyo kwamba ni pretty kiasi sawa kama
hii sehemu ya juu ya picha.

345
00:20:00,260 --> 00:20:01,490
>> Lakini nini inakuja baada ya kwamba?

346
00:20:01,490 --> 00:20:04,980
Naam, napenda kwenda mbele na kujikwamua
ya kundi zima la hii.

347
00:20:04,980 --> 00:20:09,650
Tutaweza rewind katika wakati ambapo sisi tu
na s, ambayo sasa ni thabiti na

348
00:20:09,650 --> 00:20:10,940
mstari mmoja hadi huko.

349
00:20:10,940 --> 00:20:11,400
>> Mimi kuangalia.

350
00:20:11,400 --> 00:20:13,450
Kama s ni sawa sawa na 0.

351
00:20:13,450 --> 00:20:18,670
Sasa, haraka upande kumbuka, wakati
wapate kurudi GetString 0?

352
00:20:18,670 --> 00:20:19,580
Kuna si kumbukumbu ya kutosha.

353
00:20:19,580 --> 00:20:19,880
Haki?

354
00:20:19,880 --> 00:20:22,310
>> Ni nadra kwamba hii kinaenda kutokea,
hakika kwenye kompyuta hiyo ni

355
00:20:22,310 --> 00:20:24,740
got mamia ya megs au
hata gigs ya RAM.

356
00:20:24,740 --> 00:20:27,080
Lakini inaweza, katika nadharia, kurudi
0, hasa kama

357
00:20:27,080 --> 00:20:28,080
mtumiaji hana kushirikiana.

358
00:20:28,080 --> 00:20:31,640
Kuna njia ya kujifanya kama una si
inputted kitu na hila

359
00:20:31,640 --> 00:20:34,100
GetString katika kurudi
0 ufanisi.

360
00:20:34,100 --> 00:20:35,470
>> Hivyo ni kwenda kuangalia kwa ajili hiyo.

361
00:20:35,470 --> 00:20:39,430
Kwa sababu kama mtu wa kwenu wameanza
kupata, tayari, makosa segmentation -

362
00:20:39,430 --> 00:20:42,280
ambayo ina pengine imekuwa chanzo
ya kuchanganyikiwa baadhi ya -

363
00:20:42,280 --> 00:20:46,150
wale ni karibu daima matokeo
ya kumbukumbu-kuhusiana makosa.

364
00:20:46,150 --> 00:20:50,440
Namna fulani wewe messed up kwa kuzingatia
pointer, hata kama hukujua

365
00:20:50,440 --> 00:20:51,530
kulikuwa pointer.

366
00:20:51,530 --> 00:20:55,260
Hivyo unaweza kuwa ikiwa segmentation
makosa kama mapema wiki moja kutumia

367
00:20:55,260 --> 00:21:02,100
kitu kama kwa kitanzi au wakati
kitanzi na safu na kwenda mbali mno

368
00:21:02,100 --> 00:21:05,900
zamani ya mipaka ya safu baadhi ya kwamba
wewe alitangaza, katika wiki mbili katika

369
00:21:05,900 --> 00:21:06,690
fulani.

370
00:21:06,690 --> 00:21:09,220
>> Unaweza wamefanya hivyo hata katika tatizo
kuweka nne na kuzuka.

371
00:21:09,220 --> 00:21:12,910
Hata ingawa pengine hawajaona
yoyote nyota katika kanuni ya usambazaji kwa

372
00:21:12,910 --> 00:21:17,410
Kuzuka, zinageuka kuwa wale GRect
na GOval na wengine vile mambo,

373
00:21:17,410 --> 00:21:19,650
wale ni kweli kuyatumia
chini ya Hood.

374
00:21:19,650 --> 00:21:23,430
>> Lakini Stanford, kama sisi, aina ya ngozi
kwamba kina angalau kwa ajili ya maktaba

375
00:21:23,430 --> 00:21:26,540
madhumuni, kiasi kama sisi kufanya
kwa kamba na * Char.

376
00:21:26,540 --> 00:21:30,060
Lakini GRect na GOval na wale wote
mambo nyie ni au watakuwa kutumia

377
00:21:30,060 --> 00:21:32,630
wiki hii ni hatimaye
kumbukumbu anwani.

378
00:21:32,630 --> 00:21:33,650
Wewe si tu kujua.

379
00:21:33,650 --> 00:21:37,240
>> Hivyo si ajabu basi, pengine,
kwamba waweza safari juu ya baadhi ya

380
00:21:37,240 --> 00:21:38,580
segmentation makosa.

381
00:21:38,580 --> 00:21:41,290
Lakini nini kuvutia hapa sasa,
kama baada ya sisi kuangalia kwa 0 sisi kufanya

382
00:21:41,290 --> 00:21:43,460
kamba t anapata s.

383
00:21:43,460 --> 00:21:44,690
Naam, napenda kutangaza t.

384
00:21:44,690 --> 00:21:47,730
Mimi nina kwenda kuteka ni kama mraba,
32 bits, simu yake t.

385
00:21:47,730 --> 00:21:49,740
Na kisha mimi naenda kufanya anapata s.

386
00:21:49,740 --> 00:21:51,130
>> Naam, hiyo ina maana gani?

387
00:21:51,130 --> 00:21:53,280
Naam, ni ngumu kidogo kufikiri
kuhusu hilo picha ya busara.

388
00:21:53,280 --> 00:21:55,025
Lakini hebu fikiria kuhusu
nini ndani ya x?

389
00:21:55,025 --> 00:21:59,430
Nini halisi ndani ya kutofautiana hii?

390
00:21:59,430 --> 00:22:01,500
Ox123 thamani.

391
00:22:01,500 --> 00:22:05,815
>> Hivyo wakati mimi kusema kamba t anapata s, kwamba tu
likiwa na maana ya kuchukua idadi

392
00:22:05,815 --> 00:22:10,070
katika s, ambayo ni Ox123 na kuiweka Ox123.

393
00:22:10,070 --> 00:22:13,740
Au pictorially, kama mimi aina ya kufikirika
mbali na undani kwamba ina

394
00:22:13,740 --> 00:22:16,600
athari za literally kufanya
hili pia.

395
00:22:16,600 --> 00:22:22,110
>> Hivyo sasa, kufikiri nyuma wiki iliyopita wakati
sisi tuliendelea kibepari T. mimi

396
00:22:22,110 --> 00:22:23,800
alifanya T mabano 0.

397
00:22:23,800 --> 00:22:27,150
Naam, T mabano 0, hata kama ni
pointer, unaweza kutibu kama ingawa

398
00:22:27,150 --> 00:22:29,220
ni safu, na mraba
bracket nukuu.

399
00:22:29,220 --> 00:22:31,550
>> Hivyo ambapo ni T mabano 0?

400
00:22:31,550 --> 00:22:32,990
Naam, ni h.

401
00:22:32,990 --> 00:22:36,800
Na hivyo wakati sisi kutumia kwamba mstari wa kanuni,
mbili ya juu, ambayo ni kwa kuwa type.h c

402
00:22:36,800 --> 00:22:38,460
header faili, hiyo ambapo
ni alitangaza.

403
00:22:38,460 --> 00:22:44,410
Wewe ni kuyafanyia hii H. Lakini ya
Bila shaka, hiyo ni sawa kamili h kwamba

404
00:22:44,410 --> 00:22:46,540
ndani ya s, hivyo kusema.

405
00:22:46,540 --> 00:22:51,930
Na hivyo sasa una iliyopita au
mtaji wote wawili awali na

406
00:22:51,930 --> 00:22:53,120
kinachojulikana nakala.

407
00:22:53,120 --> 00:22:56,620
Sababu hukutaka kufanya nakala katika
njia ambayo binadamu wanataka iwe.

408
00:22:56,620 --> 00:22:59,710
>> Hivyo kile ilikuwa fix hapa,
katika wiki ya mwisho copy1.c?

409
00:22:59,710 --> 00:23:03,070

410
00:23:03,070 --> 00:23:05,580
Kazi, hivyo tunaweza kweli
nakala kamba.

411
00:23:05,580 --> 00:23:08,700
Na kimsingi, nini tunahitaji
kufanya ili nakala kamba?

412
00:23:08,700 --> 00:23:12,070
>> Naam, katika toleo hili kijani hapa mimi nina
kwenda kufanya ni haki ya chini ya kiwango.

413
00:23:12,070 --> 00:23:14,260
Ni kweli kuna kazi
waweze kusaidia kwa hili.

414
00:23:14,260 --> 00:23:17,710
Lakini moja ya msingi zaidi, na wengi
moja ukoo, angalau, hivi karibuni kuwa

415
00:23:17,710 --> 00:23:19,600
familiar kwetu, ni yafuatayo -

416
00:23:19,600 --> 00:23:21,910
hivyo moja juu ya mstari wa kwanza
wa kanuni katika kijani sasa.

417
00:23:21,910 --> 00:23:23,970
>> Mimi tu rewrote s kama * Char.

418
00:23:23,970 --> 00:23:25,250
Hakuna kazi
tofauti huko.

419
00:23:25,250 --> 00:23:28,790
Mimi tu akatupa mbali na maktaba CS50
Mimi nina wito yake ni nini, * Char.

420
00:23:28,790 --> 00:23:31,640
>> Sasa dot, dot, dot, kwa sababu kulikuwa
baadhi ya kuangalia kosa si kwamba

421
00:23:31,640 --> 00:23:33,200
kuvutia kwa majadiliano juu tena.

422
00:23:33,200 --> 00:23:34,710
Hivyo sasa ni alitangaza t.

423
00:23:34,710 --> 00:23:35,780
Hiyo pia ni * Char.

424
00:23:35,780 --> 00:23:38,280
Hivyo nilitoa mraba kidogo juu ya
screen kama kabla.

425
00:23:38,280 --> 00:23:41,870
>> Lakini juu ya upande wa kulia, malloc,
sisi alisema ni kumbukumbu kutenga.

426
00:23:41,870 --> 00:23:44,130
Hivyo kutenga baadhi ya chunk ya kumbukumbu.

427
00:23:44,130 --> 00:23:48,830
Na jinsi ka wengi kufanya sisi kweli
wanataka kutenga, nini ni kuonekana?

428
00:23:48,830 --> 00:23:50,340
>> Naam, urefu wa kamba ya s.

429
00:23:50,340 --> 00:23:52,310
Hivyo kama ni hujambo kwamba
kwenda kuwa tano.

430
00:23:52,310 --> 00:23:53,950
Tutaweza kusema h-e-l-l-o.

431
00:23:53,950 --> 00:23:55,090
Hivyo tano ka.

432
00:23:55,090 --> 00:23:57,960
>> Lakini basi pamoja na 1, kwa nini 1?

433
00:23:57,960 --> 00:23:58,830
Tabia 0.

434
00:23:58,830 --> 00:24:03,640
Kama hatuwezi kuondoka chumba kwa guy hii sisi
ili kujenga hali ya ajali

435
00:24:03,640 --> 00:24:05,600
ambapo kamba ni h-e-l-l-o.

436
00:24:05,600 --> 00:24:08,470
Na kisha wakati ujao GetString ni
kuitwa na mimi aina katika, kwa mfano,

437
00:24:08,470 --> 00:24:14,020
Daudi, D-a-v-i-d, kompyuta ni kwenda
kufikiri kwamba s ni kweli

438
00:24:14,020 --> 00:24:18,900
h-e-l-l-o-d-a-v-i-d sababu kuna
hakuna kuvunja katika kati ya maneno hayo.

439
00:24:18,900 --> 00:24:19,810
>> Hivyo tunahitaji kuwa mapumziko.

440
00:24:19,810 --> 00:24:20,720
Hivyo hatutaki tano.

441
00:24:20,720 --> 00:24:22,100
Tunataka ka sita.

442
00:24:22,100 --> 00:24:23,110
>> Na ka mimi kusema.

443
00:24:23,110 --> 00:24:25,220
Lakini ni kweli wakati ukubwa wa Char.

444
00:24:25,220 --> 00:24:28,040
Kitaalam Char ni karibu
daima Byte moja.

445
00:24:28,040 --> 00:24:31,030
>> Lakini tu kufanya kanuni zetu portable,
hivyo kusema, hivyo kwamba ni kazi ya

446
00:24:31,030 --> 00:24:33,750
tofauti kompyuta hata kama walivyotarajiwa
kuwa tofauti kidogo chini ya

447
00:24:33,750 --> 00:24:36,590
Hood, mimi nina kwenda generically
wanasema ukubwa wa Char ili

448
00:24:36,590 --> 00:24:37,660
kanuni yangu daima kazi.

449
00:24:37,660 --> 00:24:40,610
Na mimi hawana recompile tu
kwa sababu mimi kuboresha kompyuta yangu au kutumia

450
00:24:40,610 --> 00:24:42,140
baadhi ya jukwaa tofauti.

451
00:24:42,140 --> 00:24:45,300
>> Hivyo mimi nimepata 6 ukubwa wa mara
Char, ambayo hufanyika kuwa 1.

452
00:24:45,300 --> 00:24:47,440
Ili malloc njia inaweza
nipe ka sita.

453
00:24:47,440 --> 00:24:49,140
Nini ni kwamba kweli kufanya?

454
00:24:49,140 --> 00:24:52,810
Vizuri, basi mimi unaendelea nyuma katika muda hapa
ambapo sisi ni katika hadithi.

455
00:24:52,810 --> 00:24:57,620
>> Hivyo kama mimi kurejea hapa, nimekuwa alitangaza
* Char kuitwa t.

456
00:24:57,620 --> 00:25:00,280
Nimekuwa sasa inaitwa malloc kwa ka sita.

457
00:25:00,280 --> 00:25:06,400
Na sasa mimi nina kwenda kuteka wale sita
ka tu kama safu ya awali.

458
00:25:06,400 --> 00:25:10,570
Lakini mimi kwa kweli hawajui nini
ndani ya safu hii.

459
00:25:10,570 --> 00:25:14,640
>> Kama wewe kutenga kumbukumbu zinageuka kuwa
huwezi kuamini kwamba kuna baadhi ya

460
00:25:14,640 --> 00:25:15,810
inayojulikana thamani huko.

461
00:25:15,810 --> 00:25:18,400
Wangeweza kutumiwa na kitu
mwingine, baadhi ya kazi nyingine, baadhi ya wengine

462
00:25:18,400 --> 00:25:19,630
mstari wa kanuni kwamba aliandika.

463
00:25:19,630 --> 00:25:22,870
Hivyo tutaweza ujumla kuwaita hawa takataka
maadili na kuteka yao, pengine, kama

464
00:25:22,870 --> 00:25:26,170
alama ya kuuliza, tu kuonyesha kwamba sisi
sijui nini ni kweli huko.

465
00:25:26,170 --> 00:25:30,390
Na kwamba hakuna mpango mkubwa ya muda mrefu kama sisi
ni smart kutosha overwrite wale

466
00:25:30,390 --> 00:25:34,550
taka maadili na namba au
chars kwamba sisi huduma ya juu.

467
00:25:34,550 --> 00:25:36,340
>> Hivyo katika kesi hii je, Mimi naenda kufanya nini?

468
00:25:36,340 --> 00:25:38,670
Naam, line yangu ya maadili ya
ijayo, nina nne.

469
00:25:38,670 --> 00:25:41,350
int i kupata 0, n anapata
urefu wa kamba s.

470
00:25:41,350 --> 00:25:42,750
Hivyo familiar kwa kitanzi.

471
00:25:42,750 --> 00:25:45,875
Mimi ni chini ya au sawa na n,
ambayo kwa kawaida ni juu.

472
00:25:45,875 --> 00:25:47,500
>> Lakini wakati huu ni makusudi.

473
00:25:47,500 --> 00:25:51,890
I + +, na kisha mimi tu kufanya
t mabano i anapata s.

474
00:25:51,890 --> 00:25:56,320
Kwa sababu picha yangu inaonekana kama hii katika
wakati huu, kuhifadhiwa katika t ni

475
00:25:56,320 --> 00:25:59,530
anuani ya chunk kwamba random ya kumbukumbu
ambao maadili ni haijulikani.

476
00:25:59,530 --> 00:26:03,030
Lakini kwa haraka kama mimi kufanya t bracket
0 kwamba unaweka mimi hapa.

477
00:26:03,030 --> 00:26:07,430
>> Na nini mwisho juu kupata inayotolewa huko?

478
00:26:07,430 --> 00:26:08,740
Sisi kuishia kuweka h.

479
00:26:08,740 --> 00:26:11,170
Kwa sababu hiyo ni nini saa s mabano 0.

480
00:26:11,170 --> 00:26:14,300
Na kisha kitu kimoja kwa ajili
e, na l, na l, na o.

481
00:26:14,300 --> 00:26:17,930
>> n, kwa nini mimi kwenda juu kupitia
sawa na n?

482
00:26:17,930 --> 00:26:19,200
Sababu ya tabia 0.

483
00:26:19,200 --> 00:26:23,580
Hivyo tu kuwa wazi, basi, kama mimi kwa kweli
kufuta chochote haya ya takataka

484
00:26:23,580 --> 00:26:28,870
maadili ni kweli na kisha kuteka katika
kile kutarajia, hii ni s mabano 1, 2,

485
00:26:28,870 --> 00:26:32,440
3, 4, pamoja na hiyo trailing
tabia mpya.

486
00:26:32,440 --> 00:26:36,080
>> Na hivyo sasa kama sisi iliendelea zamani dot,
dot, dot katika toleo hili sahihi

487
00:26:36,080 --> 00:26:41,930
na mtaji t mabano 0 napenda, ya
Bila shaka, kuwa kuyafanyia tu hii

488
00:26:41,930 --> 00:26:47,050
guy hapa, ambayo conceptually,
ilikuwa hatimaye lengo.

489
00:26:47,050 --> 00:26:48,040
Hivyo kwamba ni pointer wote ni.

490
00:26:48,040 --> 00:26:51,430
>> Na tumekuwa kutumia yao kwa muda wa wiki
sasa katika mazingira ya masharti.

491
00:26:51,430 --> 00:26:53,530
Lakini chini ya Hood wao uko
kidogo ngumu zaidi.

492
00:26:53,530 --> 00:26:57,520
Lakini kama unafikiri juu yao katika hii
fomu mchoro napendekeza kwamba wao ni

493
00:26:57,520 --> 00:27:01,720
pengine si inatisha kwamba wote kama wao
wapate kwanza kuonekana katika mtazamo wa kwanza,

494
00:27:01,720 --> 00:27:04,730
hasa kwa vile syntax mpya.

495
00:27:04,730 --> 00:27:07,290
Maswali yoyote juu ya kuyatumia,
masharti, au chars?

496
00:27:07,290 --> 00:27:07,580
Yeah?

497
00:27:07,580 --> 00:27:09,252
>> Watazamaji: Je, unaweza kurudi nyuma
kwa [inaudible]?

498
00:27:09,252 --> 00:27:10,502
>> SPIKA 1: Uhakika.

499
00:27:10,502 --> 00:27:14,058

500
00:27:14,058 --> 00:27:19,525
>> Watazamaji: Hivyo jinsi ya kuja katika sana yako ya mwisho
mstari, huna t * Mpya

501
00:27:19,525 --> 00:27:21,513
na s * katika mstari?

502
00:27:21,513 --> 00:27:23,004
Je, si una kumbukumbu -

503
00:27:23,004 --> 00:27:24,640
>> SPIKA 1: Ah, swali zuri.

504
00:27:24,640 --> 00:27:26,800
Kwa nini si mimi kuwa t * na * s?

505
00:27:26,800 --> 00:27:30,340
Sababu kwa ufupi, wiki iliyopita, kama katika yetu
wabadilishane kazi, mimi kusema kwamba wakati

506
00:27:30,340 --> 00:27:33,350
nimepata pointer njia
ambayo wewe kwenda huko kama tulivyofanya

507
00:27:33,350 --> 00:27:36,590
kimwili juu ya hatua, ilikuwa kwa kweli
kutumia operator nyota.

508
00:27:36,590 --> 00:27:40,570
>> Ni zinageuka kuwa hii mabano mraba-
nukuu ni nini Tutamwita kisintaksia

509
00:27:40,570 --> 00:27:44,190
sukari, ambayo ni njia tu sexy ya
akisema shorthand ni nukuu kwa

510
00:27:44,190 --> 00:27:45,950
nini hasa ni kuelezea.

511
00:27:45,950 --> 00:27:49,385
Lakini ni kidogo Intuitive zaidi.

512
00:27:49,385 --> 00:27:53,510
Na katika hatari ya kufanya hii wanaonekana zaidi
ngumu kuliko mahitaji kwa kuwa,

513
00:27:53,510 --> 00:27:56,990
nini kweli kinachoendelea hapa
ni yafuatayo -

514
00:27:56,990 --> 00:28:01,450
Kama mimi kusema * t kwamba maana ya kwenda
anuani ya kuhifadhiwa katika t.

515
00:28:01,450 --> 00:28:04,350
>> Hivyo literally, kama t ni hifadhi ya
anuani ya kwamba h

516
00:28:04,350 --> 00:28:07,300
awali, t * njia kwenda hapa.

517
00:28:07,300 --> 00:28:10,730
Sasa, je, t mabano 0 maana?

518
00:28:10,730 --> 00:28:11,560
Huo halisi kitu.

519
00:28:11,560 --> 00:28:13,510
Ni tu zaidi kidogo ya mtumiaji
kirafiki kuandika.

520
00:28:13,510 --> 00:28:14,430
>> Lakini nina kufanyika bado.

521
00:28:14,430 --> 00:28:17,800
Siwezi kusema tu t * anapata * s.

522
00:28:17,800 --> 00:28:19,440
Kwa sababu gani mimi kuwa kufanya, basi?

523
00:28:19,440 --> 00:28:22,950
Ningependa kuwa na kuweka h, h, h, h, h
katika jambo zima.

524
00:28:22,950 --> 00:28:22,995
Haki?

525
00:28:22,995 --> 00:28:26,020
>> Kwa sababu * t ni kwenda anuani katika t.

526
00:28:26,020 --> 00:28:27,580
Lakini sisi ni ndani ya kitanzi.

527
00:28:27,580 --> 00:28:32,150
Na thamani gani mimi incrementing,
bila shaka, juu ya kila iteration?

528
00:28:32,150 --> 00:28:32,690
i.

529
00:28:32,690 --> 00:28:34,590
>> Lakini kuna nafasi
hapa, sawa?

530
00:28:34,590 --> 00:28:37,870
Hata ingawa hii anahisi kama ni kupata
kidogo kisasa zaidi

531
00:28:37,870 --> 00:28:40,730
kuliko nukuu mraba-bracket
tumekuwa kutumika kwa muda -

532
00:28:40,730 --> 00:28:43,840
basi mimi tengua h wangu mabadiliko huko -

533
00:28:43,840 --> 00:28:48,870
hata ingawa hii sasa ni kupata kidogo
fancier, wazo msingi, kama t *

534
00:28:48,870 --> 00:28:53,630
maana hapa na t * ni tu
kwenda anuani katika t.

535
00:28:53,630 --> 00:28:54,990
>> Lakini kile ambacho kilikuwa anwani katika t?

536
00:28:54,990 --> 00:28:56,850
idadi sisi kuendelea kutumia?

537
00:28:56,850 --> 00:29:00,540
Kama Ox456, hebu kuleta kwamba nyuma
tu kwa ajili ya majadiliano.

538
00:29:00,540 --> 00:29:05,380
Naam, kama nataka kupata saa e katika
t kamba, mimi tu wanataka kwenda,

539
00:29:05,380 --> 00:29:06,460
kimsingi, 456.

540
00:29:06,460 --> 00:29:09,230
>> Au tuseme, 457.

541
00:29:09,230 --> 00:29:10,590
Mimi tu haja ya kuongeza moja.

542
00:29:10,590 --> 00:29:11,790
Lakini siwezi kufanya hivyo, haki?

543
00:29:11,790 --> 00:29:14,680
Kwa sababu t, hata kama mimi kuendelea kuchora
sasa kama mshale, ni tu

544
00:29:14,680 --> 00:29:16,570
posta, Ox456.

545
00:29:16,570 --> 00:29:21,400
Na kama mimi kuongeza moja kwamba, au zaidi
kwa ujumla, kama mimi kuongeza mimi kwa kuwa naweza

546
00:29:21,400 --> 00:29:24,350
kweli kupata hasa ambapo nataka.

547
00:29:24,350 --> 00:29:26,260
Hivyo kama mimi kwa kweli kufanya hili -

548
00:29:26,260 --> 00:29:28,970
na hii ni nini sasa inaitwa
pointer hesabu -

549
00:29:28,970 --> 00:29:30,375
Naweza kuondoa mstari huu.

550
00:29:30,375 --> 00:29:33,550
Ambayo ni, kusema ukweli, nadhani wazi na
zaidi kidogo ya mtumiaji wa kirafiki kusoma.

551
00:29:33,550 --> 00:29:35,970
Lakini hii ni si chini ya sahihi.

552
00:29:35,970 --> 00:29:38,570
>> Line hii ya maadili ya sasa ni kutumia
pointer hesabu.

553
00:29:38,570 --> 00:29:40,920
Ni kusema kwenda
kufuatia anwani -

554
00:29:40,920 --> 00:29:44,670
chochote mwanzo wa t ni, ambayo
ni t plus i, ambayo awali

555
00:29:44,670 --> 00:29:45,730
ni 0, ambayo ni kubwa.

556
00:29:45,730 --> 00:29:49,280
Sababu hiyo ina maana ya mwanzo wa t
pamoja na 1, plus 2, pamoja na 3, na kadhalika.

557
00:29:49,280 --> 00:29:51,030
Na mpango huo na s.

558
00:29:51,030 --> 00:29:52,750
>> Hivyo kisintaksia sukari kwa ajili hii.

559
00:29:52,750 --> 00:29:55,900
Lakini kuelewa nini kweli kinachoendelea
chini ya Hood, napenda kusema,

560
00:29:55,900 --> 00:29:57,410
ni kweli ni muhimu katika yenyewe.

561
00:29:57,410 --> 00:30:00,620
Sababu ina maana sasa kuna si
mengi zaidi uchawi kwenda kwenye

562
00:30:00,620 --> 00:30:01,620
chini ya Hood.

563
00:30:01,620 --> 00:30:03,920
Kuna si kwenda kuwa wengi zaidi
tabaka kwamba tunaweza peel nyuma kwa ajili yenu.

564
00:30:03,920 --> 00:30:04,810
Hii ni c.

565
00:30:04,810 --> 00:30:06,410
Na hii ni programu.

566
00:30:06,410 --> 00:30:08,002
Nzuri kwa kweli swali.

567
00:30:08,002 --> 00:30:11,570
>> Haki wote, hivyo hii ni kwamba Buggy
mpango mimi alikuwa akimaanisha mapema.

568
00:30:11,570 --> 00:30:12,650
wabadilishane ilikuwa kiujanja.

569
00:30:12,650 --> 00:30:14,070
Kama hawakuwa wanaonekana kazi.

570
00:30:14,070 --> 00:30:17,390
Kukumbuka kuwa tu kama maziwa na
maji ya machungwa - ambayo mimi kuanza

571
00:30:17,390 --> 00:30:18,660
kunywa maandamano ya leo.

572
00:30:18,660 --> 00:30:22,220
Hivyo tu kama na maji ya machungwa na
maziwa, hatukuwa na kutumia

573
00:30:22,220 --> 00:30:26,200
muda kutofautiana, TMP, kushikilia
muda ili kwamba tunaweza kisha

574
00:30:26,200 --> 00:30:28,820
mabadiliko ya thamani yake na kisha update b.

575
00:30:28,820 --> 00:30:32,870
>> Lakini kazi hii, sisi alisema, au hii
mpango ambapo kazi hii ilikuwa

576
00:30:32,870 --> 00:30:35,670
imeandikwa ilikuwa na makosa na dosari kubwa, kwa nini?

577
00:30:35,670 --> 00:30:38,870

578
00:30:38,870 --> 00:30:39,090
Ndiyo?

579
00:30:39,090 --> 00:30:42,471
>> Watazamaji: [inaudible].

580
00:30:42,471 --> 00:30:44,940
>> SPIKA 1: Hasa, wakati
wewe piga wabadilishane -

581
00:30:44,940 --> 00:30:47,820
au zaidi kwa ujumla, wakati wewe
kuwaita zaidi ya kazi yoyote -

582
00:30:47,820 --> 00:30:51,210
kama hoja ya kazi kwamba ni
mali, hivyo kusema, ints na chars

583
00:30:51,210 --> 00:30:56,740
na mara mbili na ikifungwa, mambo bila
nyota, wewe ni kupita katika nakala ya

584
00:30:56,740 --> 00:30:57,540
Hoja.

585
00:30:57,540 --> 00:31:01,580
Hivyo kama alikuwa 1 x na y alikuwa 2, ni kwenda
kuwa 1 na b ni kwenda kuwa 2.

586
00:31:01,580 --> 00:31:05,250
Lakini wao wanaenda kuwa tofauti chunks
ya bits, chunks tofauti ya

587
00:31:05,250 --> 00:31:07,540
kumbukumbu kwamba kutokea kwa kuwa hifadhi ya
kufanana maadili.

588
00:31:07,540 --> 00:31:12,160
>> Hivyo kanuni hii ni super kamili
saa swapping b na.

589
00:31:12,160 --> 00:31:13,850
Siyo nzuri katika swapping -

590
00:31:13,850 --> 00:31:15,290
katika mfano wa mwisho wa wiki -

591
00:31:15,290 --> 00:31:16,390
x na y.

592
00:31:16,390 --> 00:31:18,780
Sababu tena, wao ni
katika upeo vibaya.

593
00:31:18,780 --> 00:31:21,310
>> Sasa, jinsi gani sisi kwenda kuhusu fixing hili?

594
00:31:21,310 --> 00:31:23,140
Tulikuwa na kufanya kazi
kuangalia uglier kidogo.

595
00:31:23,140 --> 00:31:25,250
Lakini tena, fikiria nini
hii ina maana tu.

596
00:31:25,250 --> 00:31:27,840

597
00:31:27,840 --> 00:31:31,500
>> Na kweli, basi mimi, kwa ajili ya msimamo,
kubadili jambo moja hivyo ni sawa na

598
00:31:31,500 --> 00:31:33,200
nini sisi tu alifanya.

599
00:31:33,200 --> 00:31:35,690
Kama nilivyoeleza wiki iliyopita, haina
jambo ambapo unaendelea.

600
00:31:35,690 --> 00:31:38,120
Kwa kweli, kwa kawaida bila kuweka
nyota karibu na jina kutofautiana.

601
00:31:38,120 --> 00:31:40,750
Lakini nadhani ingekuwa rahisi kidogo
kufikiria * karibu na

602
00:31:40,750 --> 00:31:44,910
data aina kama maana ni pointer
kwa int katika kesi hii.

603
00:31:44,910 --> 00:31:46,270
>> Hivyo kile mimi nafanya nini hapa?

604
00:31:46,270 --> 00:31:49,590
Mimi kusema wala kunipa int
ikifuatiwa na int mwingine,

605
00:31:49,590 --> 00:31:50,810
wito wao na b.

606
00:31:50,810 --> 00:31:52,460
Nipe anwani ya int.

607
00:31:52,460 --> 00:31:53,960
Nipe anwani ya int mwingine.

608
00:31:53,960 --> 00:31:56,330
Kuwaita wale unashughulikia b na.

609
00:31:56,330 --> 00:32:00,860
>> Na kisha kwa kutumia nukuu * chini
chini, kwenda kwa kila moja ya anwani wale

610
00:32:00,860 --> 00:32:05,290
kama zinahitajika ama kupata
au kuweka thamani yake.

611
00:32:05,290 --> 00:32:07,400
Lakini kuna ubaguzi hapa.

612
00:32:07,400 --> 00:32:11,130
Kwa nini mimi si kuwa * karibu na TMP?

613
00:32:11,130 --> 00:32:15,070
Kwa nini mimi si kufanya hivyo, kwa mfano?

614
00:32:15,070 --> 00:32:19,370
Ni anahisi kama mimi lazima tu kwenda wote
nje na kusahihisha jambo zima.

615
00:32:19,370 --> 00:32:19,752
Yeah?

616
00:32:19,752 --> 00:32:21,002
>> Watazamaji: [inaudible].

617
00:32:21,002 --> 00:32:23,280

618
00:32:23,280 --> 00:32:25,480
>> SPIKA 1: Mimi si alitangaza
TMP kama kamba.

619
00:32:25,480 --> 00:32:28,830

620
00:32:28,830 --> 00:32:34,950
Hivyo hii itakuwa kutangaza, katika kesi hii,
TMP kuwa anuani ya int.

621
00:32:34,950 --> 00:32:37,380
Lakini si kwamba kabisa nini nataka,
kwa michache ya sababu.

622
00:32:37,380 --> 00:32:38,616
>> Watazamaji: Wewe hawataki kubadilishana nao.

623
00:32:38,616 --> 00:32:41,800
>> SPIKA 1: Hasa, Sitaki wabadilishane
kitu chochote na TMP. TMP ni tu

624
00:32:41,800 --> 00:32:42,790
wiki moja ya mambo ya ajabu.

625
00:32:42,790 --> 00:32:45,150
Yote nataka ni kutofautiana
kuhifadhi baadhi ya simu.

626
00:32:45,150 --> 00:32:47,330
Mimi wala hata huduma kuhusu anwani za
katika wakati huu.

627
00:32:47,330 --> 00:32:50,530
>> Mimi haja tu bits 32 au
hivyo kuhifadhi int.

628
00:32:50,530 --> 00:32:56,690
Na mimi nataka kuweka katika bits wale 32
chochote si katika, hivyo kusema, lakini

629
00:32:56,690 --> 00:33:01,260
ni nini, tu kuwa sahihi zaidi.

630
00:33:01,260 --> 00:33:06,420
Kwa sababu kama ni anwani, * maana
kwenda huko na kupata thamani 1.

631
00:33:06,420 --> 00:33:10,560
Kwa mfano, katika mfano wa wiki iliyopita
au katika kesi ya b, kupata thamani ya 2.

632
00:33:10,560 --> 00:33:11,750
>> Basi nini kweli kinachoendelea?

633
00:33:11,750 --> 00:33:15,070
Basi mimi kuchora picha hapa kwamba mapenzi
tu tease mbali sehemu ya leo.

634
00:33:15,070 --> 00:33:18,580
Lakini hii itaendelea kuonekana
kwa muda kabisa.

635
00:33:18,580 --> 00:33:22,430
>> Hii, mimi kudai, ni nini kompyuta yako
kumbukumbu inaonekana kama wakati kukimbia

636
00:33:22,430 --> 00:33:24,060
mpango, mpango wowote.

637
00:33:24,060 --> 00:33:28,340
Wakati kukimbia mpango saa ya juu sana
ya RAM ya kompyuta yako - hivyo kufikiria

638
00:33:28,340 --> 00:33:33,530
hii mstatili, kweli, kama yako
RAM ya kompyuta au kumbukumbu, kila 101

639
00:33:33,530 --> 00:33:36,920
bilioni ka yake, kila bilioni mbili
ka, kila gigabytes mbili ya mambo yake,

640
00:33:36,920 --> 00:33:39,910
chochote wingi una ni,
hebu kuteka ni kama mstatili.

641
00:33:39,910 --> 00:33:43,260
Na mimi kudai kwamba wakati wewe kukimbia na mpango
kama Microsoft Word au Chrome

642
00:33:43,260 --> 00:33:49,220
au kitu kama hicho, bits kwamba
Microsoft au kwamba Google aliandika -

643
00:33:49,220 --> 00:33:50,910
katika kesi ya programu hizo -

644
00:33:50,910 --> 00:33:54,490
ni kubeba katika kumbukumbu ya kompyuta yako
ambapo wanaweza kuuawa zaidi

645
00:33:54,490 --> 00:33:57,520
haraka na kulishwa ndani ya CPU, ambayo
ni akili ya kompyuta.

646
00:33:57,520 --> 00:34:00,940
>> Na katika TAM wao ni kuhifadhiwa katika sana
juu ya mpango wako, hivyo kusema.

647
00:34:00,940 --> 00:34:03,300
Kwa maneno mengine, kama hii ni chunk ya
kumbukumbu, wakati wewe bonyeza mara mbili

648
00:34:03,300 --> 00:34:05,740
Microsoft Word, bits kuja
mbali ya gari ngumu.

649
00:34:05,740 --> 00:34:06,680
Wao kupata kubeba katika RAM.

650
00:34:06,680 --> 00:34:10,330
Na tutaweza kikumbo yao hadi saa ya juu sana
ya hii Mstatili conceptually.

651
00:34:10,330 --> 00:34:13,010
>> Naam, mapumziko ya kumbukumbu yako ni
kutumika kwa ajili ya mambo mbalimbali.

652
00:34:13,010 --> 00:34:16,460
Saa ya juu sana, unaweza kuona initialize
data na uninitialize data.

653
00:34:16,460 --> 00:34:20,500
Hii ina nini, kwa sehemu kubwa, na
constants au vigezo kimataifa

654
00:34:20,500 --> 00:34:21,340
kwamba kuwa na maadili.

655
00:34:21,340 --> 00:34:22,980
Lakini zaidi juu ya wale wakati mwingine.

656
00:34:22,980 --> 00:34:25,150
>> Basi una chungu, ambayo
tutaweza kuja nyuma.

657
00:34:25,150 --> 00:34:28,420
Lakini chini ni sehemu hiyo ni
hasa germane hivi sasa.

658
00:34:28,420 --> 00:34:30,210
Ni stack kinachojulikana.

659
00:34:30,210 --> 00:34:33,850
Hivyo tu kama katika ukumbi yoyote zaidi D hapa
chuo, una sania wale

660
00:34:33,850 --> 00:34:37,210
tu stack juu ya kila mmoja juu ambayo
unaweza kuweka chakula na mengineyo.

661
00:34:37,210 --> 00:34:40,139
stack katika mfumo wa kompyuta
ni sawa sana.

662
00:34:40,139 --> 00:34:42,679
Ila wakati tray, kama sisi kutumia katika
dining hall, bila shaka, ni maana

663
00:34:42,679 --> 00:34:45,710
kubeba mambo sania
au muafaka -

664
00:34:45,710 --> 00:34:49,469
kama tutaweza kuwaita - katika ya kompyuta
kumbukumbu ni kutumika kushikilia

665
00:34:49,469 --> 00:34:51,610
vigezo na maadili.

666
00:34:51,610 --> 00:34:53,929
>> Hivyo kile kweli unaendelea
chini ya Hood?

667
00:34:53,929 --> 00:34:55,820
Vizuri, basi mimi flip juu
screen hapa.

668
00:34:55,820 --> 00:34:58,370
Na hebu mkazo tu kwa
chini sehemu kwa muda.

669
00:34:58,370 --> 00:35:02,770
Kama hii ni sehemu ya chini ya yangu
kumbukumbu ya kompyuta zinageuka wakati mimi

670
00:35:02,770 --> 00:35:05,350
piga kazi kuu -
ambayo hufanyika, kusema ukweli,

671
00:35:05,350 --> 00:35:06,950
moja kwa moja kwa ajili yangu -

672
00:35:06,950 --> 00:35:10,510
Mimi kupata chunk ya kumbukumbu katika
chini ya RAM yangu hivyo kusema.

673
00:35:10,510 --> 00:35:13,390
Na hii ni wapi kuu ni
vigezo mitaa kwenda.

674
00:35:13,390 --> 00:35:16,770
Ni ambapo argc na argv labda
kwenda, na vigezo yoyote mimi

675
00:35:16,770 --> 00:35:18,170
kutangaza ndani ya kuu.

676
00:35:18,170 --> 00:35:20,260
Wao kuishia chini
ya RAM ya kompyuta yangu.

677
00:35:20,260 --> 00:35:25,040
>> Sasa tuseme kwamba wito kuu kazi
kama wabadilishane, kama ilivyokuwa wiki iliyopita?

678
00:35:25,040 --> 00:35:30,620
Naam, sisi kimsingi kuweka tray mpya,
mpya sura, kwenye chunk yangu ya kumbukumbu.

679
00:35:30,620 --> 00:35:34,160
Na mimi nina kwenda kuelezea hii kama
mali ya kazi ya kubadilishana.

680
00:35:34,160 --> 00:35:35,770
>> Sasa nini ndani ya kubadilishana?

681
00:35:35,770 --> 00:35:39,240
Vizuri, kwa kuzingatia mpango wa wiki iliyopita na
mmoja sisi tu kuona Excerpt kutoka,

682
00:35:39,240 --> 00:35:46,590
ndani ya sura ya kubadilishana, au juu ya kubadilishana ya
tray, ni nini vigezo?

683
00:35:46,590 --> 00:35:47,970
Naam, na b.

684
00:35:47,970 --> 00:35:51,850
Kwa sababu wale walikuwa hoja yake ya ndani,
pamoja na wa tatu, TMP.

685
00:35:51,850 --> 00:35:54,470
Hivyo kweli, mimi naweza kuteka hii
kidogo zaidi cleanly.

686
00:35:54,470 --> 00:35:56,680
Hebu kwenda mbele na kuondoa studio.

687
00:35:56,680 --> 00:35:58,520
Na napenda kudai kwamba unajua nini?

688
00:35:58,520 --> 00:36:00,560
>> pengine ni kwenda kuishia hapa.

689
00:36:00,560 --> 00:36:02,160
B ni kwenda kuishia hapa.

690
00:36:02,160 --> 00:36:03,810
Na TMP ni kwenda kuishia hapa.

691
00:36:03,810 --> 00:36:05,160
Sasa, kuagiza nguvu
kuwa tofauti kidogo.

692
00:36:05,160 --> 00:36:06,840
Lakini conceptually hii ni wazo.

693
00:36:06,840 --> 00:36:11,490
>> Na tu kwa pamoja, hii ni nini
Tutamwita sura ya kubadilishana, au

694
00:36:11,490 --> 00:36:12,136
messi tray.

695
00:36:12,136 --> 00:36:13,150
Na mpango huo na kuu.

696
00:36:13,150 --> 00:36:14,040
Lakini mimi si redraw kwamba.

697
00:36:14,040 --> 00:36:17,810
Lakini hilo ambapo argc na argv na yoyote
ya vigezo yake ya ndani kama x na y

698
00:36:17,810 --> 00:36:18,940
wapate kuwa kama vile.

699
00:36:18,940 --> 00:36:22,170
>> Hivyo sasa kufikiria nini kweli kinachotokea
wakati wewe piga wabadilishane.

700
00:36:22,170 --> 00:36:26,370
Wakati wewe piga wabadilishane, utekelezaji wa kanuni kama
hii, wewe ni kupita katika, katika

701
00:36:26,370 --> 00:36:30,670
Buggy toleo, b na
kama nakala za x na y.

702
00:36:30,670 --> 00:36:34,300
Hivyo kama mimi sasa kuteka hii
juu ya screen -

703
00:36:34,300 --> 00:36:36,700
got kupata bora katika hili -

704
00:36:36,700 --> 00:36:40,850
hivyo hadithi mimi alikuwa anawaambia kwa mwenyewe
alikuwa katika toleo hili Buggy, wakati sisi

705
00:36:40,850 --> 00:36:46,130
kuwaita wabadilishane kupita katika literally na b
kama integers, nini kweli kinachotokea?

706
00:36:46,130 --> 00:36:48,250
>> Vizuri, nini kweli kinachotokea ni hii.

707
00:36:48,250 --> 00:36:52,850
Hebu kwenda mbele na kuondoa tu
wazi juu ya baadhi ya nafasi hapa.

708
00:36:52,850 --> 00:36:54,720
Hivyo hii ni kumbukumbu ya kompyuta yangu.

709
00:36:54,720 --> 00:36:57,510
>> Hivyo kama mimi, kwa mfano -

710
00:36:57,510 --> 00:36:58,910
kweli hebu kufanya hivyo kwa njia hii -

711
00:36:58,910 --> 00:37:02,690
kama mimi kudai kwamba hii ni x, hifadhi
thamani 1 tu kama wiki iliyopita.

712
00:37:02,690 --> 00:37:05,930
Na hii ni y, kuhifadhi thamani
2 tu kama wiki iliyopita.

713
00:37:05,930 --> 00:37:11,370
Na hii ni kuu, wakati mimi wito wabadilishane,
hivyo kutoa mwenyewe upatikanaji na

714
00:37:11,370 --> 00:37:15,150
b na TMP, mimi nina kwenda kudai kwamba
hii ni na hii ni 1.

715
00:37:15,150 --> 00:37:16,080
>> Hii ni b.

716
00:37:16,080 --> 00:37:17,010
Hii ni 2.

717
00:37:17,010 --> 00:37:18,370
Hii inaitwa TMP.

718
00:37:18,370 --> 00:37:23,360
>> Na awali, ina baadhi ya thamani ya takataka
mpaka mimi kweli kuhifadhi ndani yake,

719
00:37:23,360 --> 00:37:24,450
ambayo ni 1.

720
00:37:24,450 --> 00:37:28,320
Kisha mimi kwenda mbele na mabadiliko ya
kuwa nini?

721
00:37:28,320 --> 00:37:29,720
B ya thamani.

722
00:37:29,720 --> 00:37:31,980
>> Na hivyo sasa mimi mbili hapa.

723
00:37:31,980 --> 00:37:34,050
Na kisha sisi alisema b anapata TMP.

724
00:37:34,050 --> 00:37:37,670
Tena, tu kama sanity kuangalia, ya tatu
mstari wa kanuni hapa tu hii

725
00:37:37,670 --> 00:37:39,440
moja, b anapata TMP.

726
00:37:39,440 --> 00:37:41,730
>> Na hivyo mwishowe, nini mimi?

727
00:37:41,730 --> 00:37:46,800
Mimi kwenda mbele na kubadili b kuwa chochote
thamani ya TMP ni, ambayo ni 1.

728
00:37:46,800 --> 00:37:48,390
Mimi wala kugusa TMP tena.

729
00:37:48,390 --> 00:37:54,100
>> Lakini sasa, tatizo ni haraka kama wabadilishane
anarudi, kwa sababu si kuwapatia

730
00:37:54,100 --> 00:37:57,540
nyuma baadhi ya thamani, kuna hakuna kurudi
kauli ya wazi katika hilo.

731
00:37:57,540 --> 00:37:59,080
Nini hasa kinatokea?

732
00:37:59,080 --> 00:38:03,480
Naam, kimsingi kumbukumbu hii yote -

733
00:38:03,480 --> 00:38:07,410
OK, inaonekana Raba anapenda
moja tu ya kidole wakati huo -

734
00:38:07,410 --> 00:38:08,180
tu kutoweka.

735
00:38:08,180 --> 00:38:10,070
>> Sasa katika hali halisi si
kwenda mahali popote.

736
00:38:10,070 --> 00:38:11,810
Lakini unaweza kufikiria ni
sasa kama alama ya kuuliza.

737
00:38:11,810 --> 00:38:14,040
Sababu ni tena
kweli katika matumizi.

738
00:38:14,040 --> 00:38:17,470
Na hakuna kitu inafanywa na maadili hayo.

739
00:38:17,470 --> 00:38:21,920
>> Hivyo katika kesi ya toleo la kijani la
kanuni hii, nini badala yake ni kuwa

740
00:38:21,920 --> 00:38:24,640
kupita katika wabadilishane?

741
00:38:24,640 --> 00:38:25,770
Basi anwani.

742
00:38:25,770 --> 00:38:28,520
Basi anwani ya x na
anuani ya y.

743
00:38:28,520 --> 00:38:35,790
Hivyo kama sisi re-kuwaambia hadithi hii moja ya mwisho
muda, na mimi kwa kweli kuteka wabadilishane tena,

744
00:38:35,790 --> 00:38:44,620
lakini pamoja na kuyatumia, hii kuwa, hii
kuwa b, na hii TMP kuwa, ni nini

745
00:38:44,620 --> 00:38:49,080
kweli kuhifadhiwa katika katika hii ya kijani
toleo la kanuni yangu ambapo mimi nina kupita

746
00:38:49,080 --> 00:38:52,110
katika anwani?

747
00:38:52,110 --> 00:38:53,780
>> Ni kwenda kuwa pointer x.

748
00:38:53,780 --> 00:38:54,890
Ili niweze kuteka mshale.

749
00:38:54,890 --> 00:38:57,310
Lakini hebu kutumia holela huo
mfano kama kabla.

750
00:38:57,310 --> 00:39:01,220
Hebu kusema kwamba hii ni
kitu kama Ox123.

751
00:39:01,220 --> 00:39:04,970
Na hii ni kwenda kuwa Ox127 kwa sababu
ni wanne ka mbali kwa sababu ni

752
00:39:04,970 --> 00:39:07,370
int, hivyo Ox127.

753
00:39:07,370 --> 00:39:09,080
>> Na tena, mimi kuchukua uhuru wa baadhi ya
pamoja na namba.

754
00:39:09,080 --> 00:39:11,430
Wao ni ndogo sana kuliko wao ingekuwa
kweli kuwa na utaratibu tofauti.

755
00:39:11,430 --> 00:39:14,350
Lakini hiyo ni jinsi gani picha
sasa ni tofauti.

756
00:39:14,350 --> 00:39:19,060
>> Lakini wakati mimi kutumia kanuni hii ya kijani
na mimi TMP int kupata *.

757
00:39:19,060 --> 00:39:25,010
* Njia ya kufanya yafuatayo, kuchukua
kushughulikia kwamba katika na kwenda kwa hiyo,

758
00:39:25,010 --> 00:39:26,190
ambayo ni 1.

759
00:39:26,190 --> 00:39:28,480
Na kwamba ni nini mimi kisha kuweka katika TMP.

760
00:39:28,480 --> 00:39:32,480
Wakati huo huo, katika mstari wa pili wa kanuni
hapa, * anapata b, hiyo ina maana gani?

761
00:39:32,480 --> 00:39:36,910
>> Naam, *, hivyo kwenda hapa anapata * b,
ambayo ina maana ya kwenda huko.

762
00:39:36,910 --> 00:39:39,310
Na kwamba maana ya kuweka thamani na pale.

763
00:39:39,310 --> 00:39:43,670
Hatimaye, mstari wa mwisho wa kanuni
tu alisema * b anapata TMP.

764
00:39:43,670 --> 00:39:48,900
>> Hivyo anasema b kwenda huko na overwrite ni pamoja na
TMP ambayo, katika kesi hii, ni kwenda

765
00:39:48,900 --> 00:39:51,520
kuwa, tena, 1.

766
00:39:51,520 --> 00:39:54,920
Na hii ni kwa nini toleo la kijani la
kanuni zetu matendo, ambapo nyekundu

767
00:39:54,920 --> 00:39:56,010
toleo kamwe alifanya.

768
00:39:56,010 --> 00:39:59,020
Ni wote tu majipu chini jinsi
kumbukumbu ni kusimamiwa na ambapo ni

769
00:39:59,020 --> 00:40:02,580
kweli kuwekwa katika yako
kompyuta RAM.

770
00:40:02,580 --> 00:40:07,270
Na kwa sasa, hiyo ni moja ya mambo
kwamba stack ni kuwa kutumika kwa ajili ya.

771
00:40:07,270 --> 00:40:09,225
>> Maswali juu ya mpangilio?

772
00:40:09,225 --> 00:40:10,380
Juu ya kuyatumia?

773
00:40:10,380 --> 00:40:11,630
Au juu ya kubadilishana?

774
00:40:11,630 --> 00:40:13,740

775
00:40:13,740 --> 00:40:17,043
>> Haki ya wote, hivyo malloc, kukumbuka,
walifanya kitu kama hiki.

776
00:40:17,043 --> 00:40:18,260
Hii ilikuwa ni super rahisi mfano.

777
00:40:18,260 --> 00:40:20,550
Na hii ilikuwa ni moja kwamba Binky
ilianzisha kwetu, angalau kabisa

778
00:40:20,550 --> 00:40:21,870
haraka, mwisho wa darasa.

779
00:40:21,870 --> 00:40:24,480
Dammit, kuna sisi kwenda tena.

780
00:40:24,480 --> 00:40:28,780
>> Hivyo kukumbuka kwamba hii ilikuwa mfano kwamba
Binky ilianzisha kwetu, angalau

781
00:40:28,780 --> 00:40:30,360
kiasi fulani haraka mwisho wa darasa.

782
00:40:30,360 --> 00:40:33,640
Na hapa sisi kutumika malloc kweli
kwa mara ya pili.

783
00:40:33,640 --> 00:40:37,330
Kwa sababu mara ya kwanza sisi kutumika kwa
kujenga RAM kutosha, kutenga RAM kutosha

784
00:40:37,330 --> 00:40:38,340
kuhifadhi kamba.

785
00:40:38,340 --> 00:40:40,250
>> Wakati huu naendelea Binky ni rahisi.

786
00:40:40,250 --> 00:40:42,465
Hivyo ni kuhifadhi tu
int, inaonekana.

787
00:40:42,465 --> 00:40:43,510
Na kwamba kabisa faini.

788
00:40:43,510 --> 00:40:46,560
Ni weird kidogo, kusema ukweli, kwa
kutumia malloc kutenga moja int.

789
00:40:46,560 --> 00:40:50,650
Lakini hatua ya claymation Nick alikuwa
kweli tu kuwaambia hadithi ya kile

790
00:40:50,650 --> 00:40:53,830
kinatokea au haina kutokea wakati
wewe kuwatendea kumbukumbu.

791
00:40:53,830 --> 00:40:56,520
>> Hivyo katika kesi hii, mpango huu
alifanya mambo machache.

792
00:40:56,520 --> 00:41:01,580
Katika kesi ya kwanza hapa, inatangaza
pointer kuitwa x kwa int.

793
00:41:01,580 --> 00:41:04,480
Ni kisha anatangaza pointer
kuitwa y int.

794
00:41:04,480 --> 00:41:06,150
Ni kisha maduka katika x, nini?

795
00:41:06,150 --> 00:41:07,110
Mtu mwingine sasa.

796
00:41:07,110 --> 00:41:09,685
Nini anapata kuhifadhiwa katika x kulingana na
mstari wa tatu wa mpango huu?

797
00:41:09,685 --> 00:41:12,380
>> Watazamaji: [inaudible].

798
00:41:12,380 --> 00:41:14,130
>> SPIKA 1: Naam, si kabisa
ka, kwa kusema.

799
00:41:14,130 --> 00:41:16,760
Kuwa sahihi zaidi sasa.

800
00:41:16,760 --> 00:41:18,325
Nini anapata kuhifadhiwa katika x?

801
00:41:18,325 --> 00:41:21,000

802
00:41:21,000 --> 00:41:22,060
anwani, nadhani habari hiyo.

803
00:41:22,060 --> 00:41:23,570
>> Hivyo nini malloc kurudi?

804
00:41:23,570 --> 00:41:26,030
malloc behaviorally kutenga
chunk ya kumbukumbu.

805
00:41:26,030 --> 00:41:27,850
Lakini jinsi gani kukupa huduma hiyo?

806
00:41:27,850 --> 00:41:29,460
Kuirudisha nini?

807
00:41:29,460 --> 00:41:32,000
anuani ya Byte kwanza
katika chunk ya kumbukumbu.

808
00:41:32,000 --> 00:41:33,020
>> Sasa, hii ni super rahisi.

809
00:41:33,020 --> 00:41:35,380
Ni moja tu Byte, ambayo ina maana ya
kushughulikia sisi ni kupata nyuma ni

810
00:41:35,380 --> 00:41:37,300
anuani ya jambo zima.

811
00:41:37,300 --> 00:41:42,070
Hivyo kuhifadhiwa katika x basi, ni anwani
ya kwamba chunk ya kumbukumbu.

812
00:41:42,070 --> 00:41:43,400
Wakati huo huo, nini kinatokea ijayo?

813
00:41:43,400 --> 00:41:45,890
Hivyo kweli, hebu kwenda mbele na
kuteka hii kwa haraka nje ya kweli.

814
00:41:45,890 --> 00:41:52,490
>> Hivyo kama sisi kwenda juu ya screen hapa na
sisi kucheza hii nje int * x na y * int

815
00:41:52,490 --> 00:41:53,740
ni kwenda kufanya nini kwa ajili yangu?

816
00:41:53,740 --> 00:41:58,280
Mimi kudai kwamba ni tu kwenda kufanya
kitu kama hiki na kuiita x, na

817
00:41:58,280 --> 00:42:00,010
hii na kuiita y.

818
00:42:00,010 --> 00:42:03,110
Wakati huo huo, mstari wa tatu wa kanuni ni
kwenda kutenga ukubwa wa int,

819
00:42:03,110 --> 00:42:06,160
ambayo hutokea kwa kuwa - pole kama nilivyosema
moja kabla ya mimi maana moja int -

820
00:42:06,160 --> 00:42:08,280
wanne ka kwenye kompyuta ya kawaida.

821
00:42:08,280 --> 00:42:09,720
Angalau na appliance CS50.

822
00:42:09,720 --> 00:42:11,490
>> Hivyo hii ni ya kwenda kutenga
yake, ambaye anajua?

823
00:42:11,490 --> 00:42:12,800
Mahali fulani nje hapa.

824
00:42:12,800 --> 00:42:15,780
Na hii ni kuhifadhiwa katika baadhi ya
anuani ya ng'ombe, ambaye anajua?

825
00:42:15,780 --> 00:42:18,330
Lakini nini kinaendelea kupata akarudi
ni kwamba anwani.

826
00:42:18,330 --> 00:42:22,270
Lakini tutaweza kuteka hii pictorially
kama tu mshale kama hiyo.

827
00:42:22,270 --> 00:42:25,430
>> Sasa katika mstari wa pili * x anapata 42.

828
00:42:25,430 --> 00:42:29,400
Je * x maana katika suala layman?

829
00:42:29,400 --> 00:42:30,040
Tu kwenda huko.

830
00:42:30,040 --> 00:42:30,960
Kwenda kwa anwani hiyo.

831
00:42:30,960 --> 00:42:35,900
Au kwa maneno mengine, kufuata
mshale na kuweka 42 huko.

832
00:42:35,900 --> 00:42:38,140
Lakini basi kitu mbaya kilichotokea
kwa Binky, haki?

833
00:42:38,140 --> 00:42:43,950
>> Kumbuka kwamba line tano hapa, * y anapata
13, kwa kweli idadi ukorofi,

834
00:42:43,950 --> 00:42:44,760
alifanya nini kwa ajili yetu?

835
00:42:44,760 --> 00:42:47,320
Naam, * y njia kwenda huko.

836
00:42:47,320 --> 00:42:50,460
Naam, hii haijawahi kutolewa
thamani bado, haki?

837
00:42:50,460 --> 00:42:54,090
kanuni hana y kuwa
initialized na kitu chochote.

838
00:42:54,090 --> 00:42:56,120
Tulikuwa x kuwa initialized
na anwani.

839
00:42:56,120 --> 00:42:57,640
Lakini y ilitangazwa juu juu.

840
00:42:57,640 --> 00:43:00,250
Lakini basi semicolon, hakuna thamani
ilikuwa kweli kuweka ndani yake.

841
00:43:00,250 --> 00:43:02,330
Hivyo ni haki ya kuita hii
thamani ya takataka.

842
00:43:02,330 --> 00:43:03,430
Nani anajua nini huko?

843
00:43:03,430 --> 00:43:07,160
Ni mabaki ya vipande kwamba walikuwa kutumika
na baadhi ya mstari wa kanuni katika uliopita

844
00:43:07,160 --> 00:43:08,300
wangu wa mpango.

845
00:43:08,300 --> 00:43:13,250
>> Hivyo kama mimi kusema kwenda huko, hii ni kama,
Mimi sijui ambapo mshale hii ni

846
00:43:13,250 --> 00:43:14,490
kwenda kuishia.

847
00:43:14,490 --> 00:43:17,720
Na kwamba wakati wewe kawaida
kupata kosa segmentation.

848
00:43:17,720 --> 00:43:22,430
Kama ajali dereference, hivyo
kuzungumza, au kwenda anuani si kwamba

849
00:43:22,430 --> 00:43:25,400
kweli anwani halali,
mambo mabaya kutokea.

850
00:43:25,400 --> 00:43:27,550
>> Na kwamba ni nini hasa kilichotokea
kufikiri Binky.

851
00:43:27,550 --> 00:43:31,060
Hivyo kukumbuka kwamba hadithi kwamba Nick alikuwa
kuwaambia hapa ilikuwa wazo moja kama nini

852
00:43:31,060 --> 00:43:34,050
Nimekuwa inayotolewa na udanganyifu wa
chaki ubaoni huko.

853
00:43:34,050 --> 00:43:35,960
X na y ni alitangaza.

854
00:43:35,960 --> 00:43:39,690
>> Kisha sisi zilizotengwa ukubwa wa
int na kuhifadhiwa katika x.

855
00:43:39,690 --> 00:43:42,130
Kisha mstari unaofuata tulivyofanya * x.

856
00:43:42,130 --> 00:43:46,070
Hii ilikuwa ni Nick uchawi wand
ya dereferencing.

857
00:43:46,070 --> 00:43:49,780
Kwamba kuweka 42 katika kumbukumbu
alisema na x.

858
00:43:49,780 --> 00:43:51,600
>> Lakini hii ni ambapo mambo
akaenda horribly vibaya.

859
00:43:51,600 --> 00:43:51,820
Haki?

860
00:43:51,820 --> 00:43:53,550
Sisi alijaribu y dereference.

861
00:43:53,550 --> 00:43:55,620
Lakini y alikuwa na baadhi ya thamani bogus, haki?

862
00:43:55,620 --> 00:43:57,720
>> Kwamba mshale katika chini upande wa kushoto
kona, si

863
00:43:57,720 --> 00:43:58,950
kweli akizungumzia kitu.

864
00:43:58,950 --> 00:44:01,520
Ni aina ya kufanya kile Mimi
alivyofanya hapa kwenye bodi.

865
00:44:01,520 --> 00:44:05,900
Hivyo mambo mabaya kutokea, segmentation
kosa, au Binky kosa, katika kesi hii.

866
00:44:05,900 --> 00:44:10,800
>> Lakini kama sisi kisha kurekebisha kwamba kwa kufanya x
anapata y jinsi gani mabadiliko ya hadithi?

867
00:44:10,800 --> 00:44:15,760
Naam, kama mimi kufanya x anapata y, hiyo ni
ufanisi sawa na kusema

868
00:44:15,760 --> 00:44:19,235
chochote hii ni, ng'ombe-kitu
ni kwenda kuwa sawa hapa,

869
00:44:19,235 --> 00:44:20,080
Ng'ombe-kitu.

870
00:44:20,080 --> 00:44:22,970
Au pictorially tutaweza kuteka mshale.

871
00:44:22,970 --> 00:44:25,530
>> Hivyo hapa juu ya bodi na Binky,
na line ya pili ya

872
00:44:25,530 --> 00:44:28,350
kanuni, * y ina maana kwenda huko.

873
00:44:28,350 --> 00:44:29,400
Ambapo ni huko?

874
00:44:29,400 --> 00:44:30,820
Maana yake ni zaidi ya hapa.

875
00:44:30,820 --> 00:44:36,050
>> Na wakati sisi update kwamba kuwa 13
tu kwenda na inahusisha

876
00:44:36,050 --> 00:44:39,470
kuandika 13 hapa sasa.

877
00:44:39,470 --> 00:44:44,130
Hivyo labda kabisa
moja kwa moja katika mtazamo wa kwanza.

878
00:44:44,130 --> 00:44:47,740
Lakini kwa kurejea na kutumia jargon huo
kwamba Binky ilikuwa kutumia hapa, hivyo

879
00:44:47,740 --> 00:44:50,485
mbili ya kwanza kutenga kuyatumia,
x na y, lakini si pointees.

880
00:44:50,485 --> 00:44:54,750
Na pointees si
ujumla kutumika mrefu.

881
00:44:54,750 --> 00:44:56,120
Lakini pointer kabisa ni.

882
00:44:56,120 --> 00:44:59,200
Lakini ni nini kuwa alisema
saa katika utaratibu wa majina Binky ya.

883
00:44:59,200 --> 00:45:01,660
>> Line hii ya pili, bila shaka,
kutenga pointee int.

884
00:45:01,660 --> 00:45:04,840
Hivyo chunk ya kumbukumbu - kama nilitoa zaidi juu ya
upande wa kulia hapo - na kuweka

885
00:45:04,840 --> 00:45:06,470
x sawa kwa uhakika na hilo.

886
00:45:06,470 --> 00:45:11,350
Hii x dereferences kuhifadhi 42 katika
kumbukumbu kwamba ni akionyesha.

887
00:45:11,350 --> 00:45:13,380
Na kisha hii, bila shaka,
ilikuwa kitu mbaya.

888
00:45:13,380 --> 00:45:15,600
Kwa sababu y hakuwa akizungumzia
katika kitu bado.

889
00:45:15,600 --> 00:45:16,530
Hii kunasa yake.

890
00:45:16,530 --> 00:45:18,240
Hivyo hii ni bado Buggy mpango.

891
00:45:18,240 --> 00:45:21,580
Tu kwa sababu sisi ni unavuma kupitia
kanuni ya mstari kwa mstari na kusema, oh vizuri,

892
00:45:21,580 --> 00:45:22,690
basi ni ajali huko.

893
00:45:22,690 --> 00:45:23,420
Hiyo ni kitu mbaya.

894
00:45:23,420 --> 00:45:26,790
Tabia mbaya ni mpango tu kwenda
mimba kabisa katika mstari huo.

895
00:45:26,790 --> 00:45:30,550
Lakini kama ungekuwa na kuondoa kugonga
kujipanga na badala yake na mawili ya mwisho

896
00:45:30,550 --> 00:45:32,470
mistari kuna hawawajui -

897
00:45:32,470 --> 00:45:35,310
kutumia pointer kazi - y
kwa uhakika na x kama t uhakika.

898
00:45:35,310 --> 00:45:39,280
Na kisha wewe dereference
y katika njia salama sana.

899
00:45:39,280 --> 00:45:41,520
>> Hivyo ambapo gani hii kuondoka sisi?

900
00:45:41,520 --> 00:45:45,350
Naam, zinageuka kuwa chini ya Hood
katika maktaba CS50, kuyatumia ni

901
00:45:45,350 --> 00:45:46,320
kutumika katika.

902
00:45:46,320 --> 00:45:48,910
Na tutaweza kweli kuanza peel
nyuma kwamba safu kabla ya muda mrefu.

903
00:45:48,910 --> 00:45:51,740
Lakini ni zamu pia, kujieleza kwamba
baadhi yenu wanaweza kuwa na mazoea na,

904
00:45:51,740 --> 00:45:54,580
hasa wale vizuri zaidi,
ni kweli kwamba ya maarufu sana

905
00:45:54,580 --> 00:45:56,390
tovuti, au kufurika stack,
siku hizi.

906
00:45:56,390 --> 00:45:58,720
>> Lakini hii kweli ina sana
kiufundi maana.

907
00:45:58,720 --> 00:46:00,160
Sisi sasa kujua stack ni.

908
00:46:00,160 --> 00:46:02,550
Ni kama mkusanyiko wa sania
ndani ya ukumbi wa kulia chakula.

909
00:46:02,550 --> 00:46:05,140
>> Au ndani ya kompyuta yako
kumbukumbu yake muafaka wale

910
00:46:05,140 --> 00:46:06,900
ambazo hutumiwa na utendaji.

911
00:46:06,900 --> 00:46:10,760
Naam, zinageuka kuwa sababu ya kwamba
rahisi sana utekelezaji wa

912
00:46:10,760 --> 00:46:14,970
kumbukumbu na muafaka juu ya kinachojulikana
stack, unaweza kweli kuchukua udhibiti

913
00:46:14,970 --> 00:46:17,050
ya mfumo wa kompyuta haki kwa urahisi.

914
00:46:17,050 --> 00:46:22,180
Unaweza hack katika mfumo kama watu
kama sisi si imeandikwa code yetu

915
00:46:22,180 --> 00:46:23,300
hasa vizuri.

916
00:46:23,300 --> 00:46:26,670
>> Kama watu kama sisi kutumia chunks
ya kumbukumbu au matumizi arrays -

917
00:46:26,670 --> 00:46:27,810
hata zaidi ya kawaida -

918
00:46:27,810 --> 00:46:31,800
lakini wakati mwingine kusahau kuangalia
mipaka ya safu yetu kama waweza

919
00:46:31,800 --> 00:46:38,470
na wewe mwenyewe wakati mwingine, na iterated
njia mbali sana siku za nyuma mwisho safu.

920
00:46:38,470 --> 00:46:40,520
Katika kesi bora, mpango wako
ili tu kukwama.

921
00:46:40,520 --> 00:46:42,280
Segmentation kosa, aina
ya aibu.

922
00:46:42,280 --> 00:46:45,480
Si kubwa, lakini siyo lazima
Jambo imekuwa mbaya.

923
00:46:45,480 --> 00:46:49,480
>> Lakini kama mpango wako ni kweli juu ya mali
watumiaji 'kompyuta, ikiwa ni mbio

924
00:46:49,480 --> 00:46:53,070
kwenye tovuti ya kwamba halisi random watu
kwenye mtandao ni kupiga, kuruhusu

925
00:46:53,070 --> 00:46:56,690
watu kushawishi mambo mabaya juu ya kanuni yako ni
ujumla si jambo zuri kwa sababu

926
00:46:56,690 --> 00:46:59,930
maana yake ni nafasi ya kuchukua
udhibiti wa kompyuta.

927
00:46:59,930 --> 00:47:01,350
Na hii ni kwenda kuangalia
kidogo fumbo.

928
00:47:01,350 --> 00:47:04,570
Lakini nilifikiri ningependa kuwatisheni ninyi kwa
mfano huu mwisho hapa.

929
00:47:04,570 --> 00:47:05,650
>> Hapa ni mfano wa kanuni.

930
00:47:05,650 --> 00:47:07,370
Na kuna Wikipedia nzuri
makala kwamba anatembea kwa njia ya

931
00:47:07,370 --> 00:47:08,530
hili kwa undani zaidi.

932
00:47:08,530 --> 00:47:13,890
Nina kuu juu ya wito chini
foo, kupita katika argv ya 1.

933
00:47:13,890 --> 00:47:15,750
Na kwamba tu ili uweze
kuendesha programu na kupita

934
00:47:15,750 --> 00:47:17,080
pembejeo holela.

935
00:47:17,080 --> 00:47:20,180
>> Na kisha foo ni alitangaza juu juu
kama kukubali kamba, au zaidi

936
00:47:20,180 --> 00:47:21,700
usahihi, * Char.

937
00:47:21,700 --> 00:47:23,860
Ni kisha anatangaza safu ya chars.

938
00:47:23,860 --> 00:47:27,130
Kuiita buffer, kwa ujumla zaidi,
ya ukubwa wa 12.

939
00:47:27,130 --> 00:47:30,900
Hivyo 12 chars unaweza fit ndani ya
ya kwamba safu kuitwa c.

940
00:47:30,900 --> 00:47:33,510
>> Na kisha anatumia kazi huu mpya,
ambayo ni mpya lakini si vigumu

941
00:47:33,510 --> 00:47:34,930
kuelewa, kumbukumbu nakala.

942
00:47:34,930 --> 00:47:39,290
Ni nakala ya kumbukumbu kutoka bar, ambayo ilikuwa
kutofautiana zamani n, chochote

943
00:47:39,290 --> 00:47:42,080
mtumiaji typed katika argv 1 katika c.

944
00:47:42,080 --> 00:47:43,090
Ngapi ka?

945
00:47:43,090 --> 00:47:44,260
urefu wa kamba ya bar.

946
00:47:44,260 --> 00:47:48,380
>> Hivyo kwa maneno mengine, kama mtumiaji aina katika
h-e-l-l-o kuingia, urefu wa kamba

947
00:47:48,380 --> 00:47:49,260
ya hodi ni tano.

948
00:47:49,260 --> 00:47:52,790
Hivyo tano ya ka wale ni kwenda kupata
kunakiliwa katika safu kuitwa c, ambayo

949
00:47:52,790 --> 00:47:54,110
ni ya kawaida 12.

950
00:47:54,110 --> 00:47:58,710
Lakini nini mtumiaji aina katika sana tena
neno hilo wahusika 13 au 14

951
00:47:58,710 --> 00:48:01,250
wahusika au wahusika 100 au zaidi?

952
00:48:01,250 --> 00:48:02,660
>> Ambapo ni wao kwenda kwenda?

953
00:48:02,660 --> 00:48:06,090
Naam, kwamba sura, kwamba tray
katika stack messi,

954
00:48:06,090 --> 00:48:06,930
wao wanaenda kwenda huko.

955
00:48:06,930 --> 00:48:10,080
Na ni tu kwenda kuanza overwriting
mambo mengine kwamba tayari

956
00:48:10,080 --> 00:48:12,880
juu ya stack kwamba, imejazwa
stack, hivyo kusema.

957
00:48:12,880 --> 00:48:14,780
>> Hivyo pictorially, kufikiria njia hii.

958
00:48:14,780 --> 00:48:17,970
Hii ni toleo la rangi ya
picha tumekuwa kuchora.

959
00:48:17,970 --> 00:48:20,060
Chini, hebu sema, ni kuu.

960
00:48:20,060 --> 00:48:24,690
Na juu, nini wewe ni kuona sasa
ni sura, rangi coded sasa, kwa

961
00:48:24,690 --> 00:48:26,090
kazi kuitwa foo.

962
00:48:26,090 --> 00:48:30,170
Lakini nini kuvutia hapa kuhusu
foo ni kwamba hapa ni sura yake.

963
00:48:30,170 --> 00:48:32,860
Hivyo ni inayotolewa kama mimi
alifanya lakini katika bluu mwanga.

964
00:48:32,860 --> 00:48:35,220
Na sasa hii ni mahali ambapo
c mabano 0 unaendelea.

965
00:48:35,220 --> 00:48:37,410
Na hii ni pale c bracket
11 ni kwenda kuishia.

966
00:48:37,410 --> 00:48:39,670
>> Kwa maneno mengine, ni hutokea kwa
ya kuwakilishwa kama mraba.

967
00:48:39,670 --> 00:48:42,320
Lakini kama wewe tu kuweka plopping ka
chini - au chars - wao ni kwenda mwisho

968
00:48:42,320 --> 00:48:46,070
hadi saa eneo 0 njia yote hadi
hadi 11 kwa sababu ni 0 indexed.

969
00:48:46,070 --> 00:48:49,170
>> Lakini pale ambapo ni tabia ya 13
kwenda kuishia?

970
00:48:49,170 --> 00:48:50,310
Ambapo wa 14?

971
00:48:50,310 --> 00:48:52,430
Ambapo ni tabia 50
kwenda kuishia?

972
00:48:52,430 --> 00:48:54,070
>> Ni kwenda kushika kwenda chini.

973
00:48:54,070 --> 00:48:57,350
Kwa sababu hata kama tumepata
picha ya pamoja na stack kupanda juu,

974
00:48:57,350 --> 00:48:59,920
anwani, ni zamu nje, kwenda kutoka
ndogo anwani, ndogo

975
00:48:59,920 --> 00:49:01,830
kuyatumia, kwa anwani kubwa.

976
00:49:01,830 --> 00:49:03,540
Hivyo tu anaendelea kwenda juu na juu.

977
00:49:03,540 --> 00:49:05,660
>> Hivyo kama mtumiaji aina katika
hello, kwamba ni kubwa.

978
00:49:05,660 --> 00:49:08,650
Hakuna mdudu, hakuna tatizo, salama ya kila mtu.

979
00:49:08,650 --> 00:49:11,940
Lakini kama mtumiaji aina katika kile tutaweza
piga kanuni ya ushindani, na kuwakilishwa

980
00:49:11,940 --> 00:49:16,040
mpangilio kama, mashambulizi, mashambulizi,
mashambulizi, mashambulizi, nini kinaweza kutokea?

981
00:49:16,040 --> 00:49:19,760
>> Naam, kama wote wa pembejeo kwamba mtumiaji
typed katika ni baadhi tu ya kirafiki

982
00:49:19,760 --> 00:49:21,540
au kukera kamba ya wahusika.

983
00:49:21,540 --> 00:49:24,050
Ni kweli mlolongo wa wahusika
kwamba kama wewe ni compiled,

984
00:49:24,050 --> 00:49:26,050
ni kweli ni kanuni.

985
00:49:26,050 --> 00:49:29,570
Labda ni kificho kwamba hufuta kila
files kwenye gari yako ngumu au anaye taka

986
00:49:29,570 --> 00:49:30,810
au kitu kama hicho.

987
00:49:30,810 --> 00:49:35,110
Taarifa kwamba nini msingi hapa ni kwamba
kama mtu mbaya got bahati

988
00:49:35,110 --> 00:49:37,830
overwrite chunk nyekundu ya kumbukumbu -

989
00:49:37,830 --> 00:49:41,080
ambayo sikuweza kuteka juu ya picha yangu lakini
hii picha hapa ina Wikipedia -

990
00:49:41,080 --> 00:49:42,890
wake kinachojulikana kurudi anwani.

991
00:49:42,890 --> 00:49:47,470
>> Wakati wa chakula anarudi, wakati wabadilishane anarudi,
jinsi gani kompyuta kujua kwenda kutoka

992
00:49:47,470 --> 00:49:49,790
hadi hapa chini hapa?

993
00:49:49,790 --> 00:49:52,920
Au katika sehemu tech juu juu, jinsi
gani kujua kwenda kutoka wabadilishane

994
00:49:52,920 --> 00:49:54,870
kanuni - 0 na 1 ya
ambayo kutunga wabadilishane -

995
00:49:54,870 --> 00:49:56,020
nyuma kuu?

996
00:49:56,020 --> 00:50:00,450
Kuna kinachojulikana kurudi anuani
kuhifadhiwa katika kwamba sura ile ile stack, juu ya

997
00:50:00,450 --> 00:50:02,140
huo mkahawa tray.

998
00:50:02,140 --> 00:50:06,080
>> Hivyo kama mtu mbaya ni wajanja kutosha
kuweka kanuni ya mashambulizi, mashambulizi ya kanuni, mashambulizi

999
00:50:06,080 --> 00:50:07,960
kanuni, na kupata bahati ya kutosha -

1000
00:50:07,960 --> 00:50:11,630
mara nyingi kwa njia ya majaribio na makosa - kwa
overwrite kwamba nyekundu kurudi anwani,

1001
00:50:11,630 --> 00:50:14,360
pamoja na anuani yake na tangazo
ya juu sana.

1002
00:50:14,360 --> 00:50:16,830
Taarifa 0835C080.

1003
00:50:16,830 --> 00:50:20,650
Imeandikwa nyuma juu juu kwa
sababu tutaweza labda kupitia upya.

1004
00:50:20,650 --> 00:50:22,050
Hii ni kwamba idadi.

1005
00:50:22,050 --> 00:50:25,790
>> Hivyo kama mtu mbaya anapata bahati ya kutosha au
ni smart kutosha overwrite nyekundu

1006
00:50:25,790 --> 00:50:29,480
strip ya kumbukumbu na anuani ya
kificho kwamba yeye au yeye ana namna fulani

1007
00:50:29,480 --> 00:50:34,980
hudungwa katika kompyuta yako, nadhani ambaye
kanuni ni kwenda kurudishwa kwa

1008
00:50:34,980 --> 00:50:38,260
haraka kama foo ni kosa utekelezaji?

1009
00:50:38,260 --> 00:50:39,440
>> guy mbaya ya kanuni.

1010
00:50:39,440 --> 00:50:43,610
Hivyo kanuni hii mashambulizi, AAA, tena, ili
kutuma spam, ili kufuta mafaili yote

1011
00:50:43,610 --> 00:50:44,500
kwenye gari yako ngumu.

1012
00:50:44,500 --> 00:50:48,740
Lakini kwamba ni nini kweli kufurika stack
ni, au overrun buffer, au

1013
00:50:48,740 --> 00:50:51,060
buffer kufurika mashambulizi.

1014
00:50:51,060 --> 00:50:54,400
>> Na ni incredibly, incredibly kawaida
siku hii na mipango imeandikwa katika

1015
00:50:54,400 --> 00:50:58,220
C, C + +, na hata baadhi ya lugha nyingine.

1016
00:50:58,220 --> 00:51:02,275
Kumbuka kwamba inatisha, tutaweza
mwisho kwa mzaha.

1017
00:51:02,275 --> 00:51:03,230
>> [Kicheko]

1018
00:51:03,230 --> 00:51:04,550
>> Kuona juu ya Jumatano.

1019
00:51:04,550 --> 00:51:07,920

1020
00:51:07,920 --> 00:51:10,310
Saa CS50 ijayo -

1021
00:51:10,310 --> 00:51:15,920
Hivyo mimi nina wote nje ya taa disk leo lakini
kusubiri, mafuta ya bure maziwa, simu ya nusu

1022
00:51:15,920 --> 00:51:17,850
kitabu, maji ya machungwa
kwamba mimi kunywa leo.

1023
00:51:17,850 --> 00:51:20,370

1024
00:51:20,370 --> 00:51:22,780
USB cable, bisibisi.

1025
00:51:22,780 --> 00:51:24,800
>> [Halisi kucheza]