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00:00:06,180 --> 00:00:07,820
>> JASON Hirschhorn: Welcome
li A5, kulħadd.

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Għandna ġimgħa eċċitanti li għandna quddiemna,
aktar għaliex hemm tant ġodda

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tiffaċċja f'din il-kamra.

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Huwa wunderbare.

6
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A lott ta 'inti hawn minn inċident,
li huwa anki aħjar.

7
00:00:15,740 --> 00:00:18,220
Allura nisperaw li int ser iżommu jingħaqdu magħna.

8
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>> Din il-ġimgħa aħna qed tmur biex jonfqu
biċċa l-kbira tat-taqsima

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tħejjija għall-kwizz.

10
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Allura kull aġenda tagħna, aħna qed tmur biex jitkellmu
ftit dwar riżorsi għall-klassi,

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iżda wkoll għall-kwizz, u mbagħad, għal darb'oħra,
jonfqu l-biċċa l-kbira tal-klassi jitkellem

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dwar mistoqsijiet.

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Ladarba aħna qed isir jwieġeb tiegħek
mistoqsijiet, jew jekk il-mistoqsijiet tiegħek

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naturalment iwassalna għal xi kodifikazzjoni, I
problemi kampjun minn midterms

15
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passat li aħna se kodiċi live fit-taqsima
flimkien li wkoll iġibu up xi oħra

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suġġetti tajba biex ikopru.

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>> Allura l-ewwel, kif konna marret permezz għall-
aħħar ftit ġimgħat biex infakkarkom

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guys, hemm ton ta 'riżorsi
disponibbli għal dan il-kors.

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Ħafna minnhom se jkun oerhört utli
biex inti kif inti tkompli

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jistudjaw għal kwizz 0, għaliex
huwa Tlieta wara nofsinhar.

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Allura kollha ġejt
jistudjaw għal bit.

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>> Hemm noti lecture u sors
kodiċi li għandek

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definittivament check out.

24
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Watch l-shorts.

25
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Iċċekkja study.cs50.net.

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U mbagħad, elenkati hawn taħt, numru
ta 'riżorsi oħra.

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>> Għal darb'oħra, kwizz 0 hija għada
fil 01:00.

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Jekk inti ma jkunux għamlu hekk diġà, check
l-About dokument Quiz 0 fuq l-

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homepage kors biex insemmu
fejn inti qed tieħu l-kwizz.

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L-kwizz jibda fil 01:10 u
jispiċċa 70 minuti wara.

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Mela jekk inti juru up wara 01:10, int
se tikseb li ħafna inqas minuti

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minn 70 li jieħdu l-kwizz.

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Sabiex tagħmel żgur li int hemm fil-ħin.

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Jekk int student estensjoni jew ikollhom
xi konsiderazzjonijiet ittestjar ieħor,

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ma jista 'jkun fil 01:00 għada.

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Iżda għal darb'oħra, tivverifika l-Quiz About 0
dokument biex tagħmel żgur li int taf meta

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tkun qed tieħu l-kwizz.

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I kiteb 75 minuta up here.

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Naħseb li d-dritt, mhux 70.

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>> Din tkopri l-materjal minn ġimgħa 0
biex lecture aħħar ġimgħa nhar l-Erbgħa.

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U għal darb'oħra, għal dan il-kwizz, per li
dokument, ikollok wieħed żewġ naħat u 8

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1/2 bi 11 karta li ikollok
għall-użu bħala noti matul il-kwizz.

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Ħafna nies, jekk mhux ħafna nies, ikollhom
sabet li l-aktar mod utli waħda

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biex jistudjaw għal l-kwizz huwa li
jagħmlu folja istudju,

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one-sider, ta 'tagħhom stess.

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Allura tħares lejn dawk tal-passat jekk
inti stajt tidher dawk li għaddew.

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Jilħqu lill-ħbieb biex tara dak
dawn qed tqegħid fuq il-vot tagħhom.

48
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>> Iżda idejn isfel, l-aħjar mod li tista '
istudju huwa li jmorru permezz kollox u

49
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Whittle l-isfel għal liema għandux jiġi stabbilit jew
ma jappartjenux fuq dak folja tal-

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karta, għaliex dan huwa biss verament
mod utli għalik li tagħmel ċert

51
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int ser permezz kollox u
jkollhom xi familjarità magħha.

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Ħafna nies, insibu, anki jekk
għandhom il-folja tal-karta seduta dritt

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jmiss lilhom fuq l-kwizz, ma dawran
għal dan, għaliex, għal darb'oħra, li ħafna

54
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proċess ta 'għaddejja mill-informazzjoni
għenhom jitgħallmu.

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>> Ħadd ma jkollu xi mistoqsijiet
dwar kwizz 0?

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Has kulħadd -

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Jien ma jmur biex tagħmel turija tal-idejn.

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Qatt f'moħħu.

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I kienet se titlob li
bdejt nistudja.

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Imma ma rridx li tagħmel inti
kollha tqajjimx idejk.

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So bħal I said - iva, Avi, imorru quddiem.

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>> AVI: What tkun ħaġa utli
li jitpoġġew fuq il-one-pager?

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>> STUDENT: Li sa inti.

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>> JASON Hirschhorn: Ikollok
biex jużaw il-ġudizzju tiegħek.

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Affarijiet utli li jitpoġġew fuq il-one-pager,
jekk inti huma konfużi dwar il-O big

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runtime ta 'tipi differenti ta' tiftix
u xorta, li jitqiegħdu fuq hemmhekk fil-

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chart dandy handy.

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B'dan il-mod, jekk int mitlub li fuq il-
kwizz, inti m'għandekx bżonn biex jippruvaw u figura

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it out jew ir-raġuni permezz tal-runtime.

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Tista 'biss kopja l-isfel.

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Jekk inti tħares lejn kwizzijiet passat, ħafna
drabi, hemm running mistoqsijiet time.

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Allura li se jkunu eżempju ta 'oġġett
ħaġa li jitpoġġew fuq one-pager tiegħek.

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>> Affarijiet oħra tajba li jitpoġġew fuq, jekk int
konfuż dwar kif tiddikjara

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funzjoni jew dak li l-partijiet differenti ta '
id-dikjarazzjoni funzjoni huma, jiktbu

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li hemm, verżjoni ġenerika
u mbagħad forsi eżempju.

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Jekk int konfuż dwar pointers,
dijagramma ta 'kif pointers xogħol

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probabbilment verament utli.

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Jekk int konfuż dwar recursion, a
kampjun funzjoni jirrikorri fuq hemmhekk

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tista 'wkoll juru li huma verament utli.

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Does li jagħtuk xi ideat?

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>> AVI: Inti jeħtieġ li jifhmu l-
proċess kompilazzjoni kollu, bħall-

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kif li x-xogħlijiet kollha?

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>> JASON Hirschhorn: Kollox
li ġie kopert tista '

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juru fuq il-kwizz.

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Mistoqsijiet -

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iżda għal darb'oħra, xi affarijiet se jkunu
peżati bil-kbir minn oħrajn.

88
00:04:11,300 --> 00:04:14,330
Xi affarijiet toħroġ mill-ġdid
u għal darb'oħra fil-klassi, fl

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lecture, u sezzjoni.

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Affarijiet oħra ma jkunux
toħroġ li spiss.

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>> Imxejna tkellem ħafna dwar # Jinkludu u
Xi ħaġa-lu x'inhuma dawn ifissru

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il-proċess kumpilazzjoni.

93
00:04:24,390 --> 00:04:29,120
Imxejna tkellem ħafna dwar GDB, riċiklaġġ,
dawk bnadar differenti li nużaw meta

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aħna jikkompilaw xi ħaġa, u liema
make15, per eżempju, tassew

95
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mezzi u ma verament.

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Aħna ma nitkellmux kemm dwar
kull pass wieħed fil-

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il-proċess kumpilazzjoni.

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Imxejna għadhom tkellmu dwar dan.

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00:04:40,410 --> 00:04:42,550
Allura huwa għadu xi ħaġa li inti
għandhom ikunu familjari mal.

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Iżda għal darb'oħra, aħna mhux se tkun -

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affarijiet li toħroġ aktar spiss fil-klassi
huma aktar probabbli li toħroġ aktar

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spiss u jkun aktar qawwi
imwieżna fuq il-kwizz.

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>> Kessaħ.

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Kwalunkwe mistoqsijiet oħra dwar kwizz 0?

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00:04:54,580 --> 00:04:57,660

106
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>> OK, so I tpoġġi lista ta '
suġġetti fuq il-bord.

107
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I marru permezz-sillabu.

108
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I marru permezz-taqsima reviżjoni minn
aħħar lejl u dawk slides biex toħroġ

109
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ma 'lista mhux eżawrjenti ta' suġġetti
li għandna koperti s'issa fl CS50

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u affarijiet li jistgħu
jidhru fuq il-kwizz.

111
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Hekk jien mhux se jmorru permezz
kull waħda waħda minn dawn.

112
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Dan ikun meħtieġ ħafna iktar
ħin milli għandna issa.

113
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Imma Nressaq dan up hawn biex nisperaw jog
memorja tiegħek dwar affarijiet li tista '

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jew jistgħu ma jkunux daqshekk familjari miegħek.

115
00:05:28,420 --> 00:05:32,850
>> And I imħabba li jqattgħu l-biċċa l-kbira ta '
taqsima jwieġeb mistoqsijiet tiegħek dwar

116
00:05:32,850 --> 00:05:35,130
Dawn is-suġġetti, suġġetti li
mhumiex koperti hawnhekk.

117
00:05:35,130 --> 00:05:36,130
Nistgħu jikteb il-kodiċi psewdo.

118
00:05:36,130 --> 00:05:40,010
Nistgħu jikteb il-kodiċi reali
sabiex jiżguraw li inti -

119
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I tista 'twieġeb il-mistoqsija tiegħek u jgħinu
kulħadd fundamentalment jifhmu

120
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ħafna ta 'dawn is-suġġetti sabiex tkun taf tħoss
ippreparat u komdu nidħlu

121
00:05:48,330 --> 00:05:50,150
l-għada kwizz.

122
00:05:50,150 --> 00:05:52,300
Sabiex tinqara fuq il-lista.

123
00:05:52,300 --> 00:05:54,780
Inti nisperaw waslu għal sezzjoni
ma 'xi mistoqsijiet kif ukoll.

124
00:05:54,780 --> 00:05:58,480
Meta int lest, jgħollu naħa tiegħek
u aħna se tibda.

125
00:05:58,480 --> 00:06:01,590

126
00:06:01,590 --> 00:06:05,200
>> Wieħed iżomm f'moħħu, il-mistoqsijiet li għandek,
m'hemm l-ebda mistoqsijiet stupidi.

127
00:06:05,200 --> 00:06:06,250
Għadda minn għala widnejna li ħafna.

128
00:06:06,250 --> 00:06:09,490
U l-mistoqsijiet li għandek, jiena lest
li bet, ħafna nies oħra kemm

129
00:06:09,490 --> 00:06:11,740
seduta hawn u jaraw
online jkollhom ukoll.

130
00:06:11,740 --> 00:06:13,770
Allura inti tista 'biss tgħin lin-nies
billi tistaqsi mistoqsijiet.

131
00:06:13,770 --> 00:06:15,070
Marcus.

132
00:06:15,070 --> 00:06:18,040
>> MARCUS: Bejn il-munzell u l-
munzell, hemm pre-allokati a

133
00:06:18,040 --> 00:06:22,880
persentaġġ ta 'memorja thats definita bħala
dan huwa għall-ċumnija jew għall-borġ?

134
00:06:22,880 --> 00:06:25,010
Jew kif ma dak ix-xogħol, eżattament?

135
00:06:25,010 --> 00:06:26,230
>> JASON Hirschhorn: mistoqsija Great.

136
00:06:26,230 --> 00:06:28,640
Jien ser lura rintraċċat ftit.

137
00:06:28,640 --> 00:06:30,910
Does kulħadd -

138
00:06:30,910 --> 00:06:31,660
jekk jogħġbok ikunu onesti hawn.

139
00:06:31,660 --> 00:06:34,130
Naf jien inti titlob sabiex jgħollu tiegħek
naħa quddiem sħabhom.

140
00:06:34,130 --> 00:06:38,510
Iżda hemm nies li jħossuhom
skomdi bl-munzell u borġ

141
00:06:38,510 --> 00:06:42,980
u tixtieq li jmorru fuq dak
u x'inhuma dawn jfisser?

142
00:06:42,980 --> 00:06:43,880
Għolli naħa tiegħek jekk -

143
00:06:43,880 --> 00:06:44,420
OK.

144
00:06:44,420 --> 00:06:45,120
Grazzi.

145
00:06:45,120 --> 00:06:48,420
Allura aħna qed tmur biex jmorru fuq il-munzell u
-borġ verament malajr u mbagħad

146
00:06:48,420 --> 00:06:50,370
jersqu lejn jwieġeb mistoqsija tiegħek.

147
00:06:50,370 --> 00:06:58,250
>> Allura jekk aħna jiġbed kaxxa biex jirrappreżentaw
memorja fil-kompjuter tiegħek, liema huma wħud

148
00:06:58,250 --> 00:07:02,160
affarijiet li jmorru f'din il-kaxxa?

149
00:07:02,160 --> 00:07:03,630
Main.

150
00:07:03,630 --> 00:07:04,020
A funzjoni prinċipali.

151
00:07:04,020 --> 00:07:05,890
Fejn ma tmur prinċipali?

152
00:07:05,890 --> 00:07:08,090
>> STUDENT: [inaudible].

153
00:07:08,090 --> 00:07:09,390
>> JASON Hirschhorn: Allura aħna ser
tpoġġi prinċipali stabbiliti hawn.

154
00:07:09,390 --> 00:07:12,180

155
00:07:12,180 --> 00:07:13,430
X'iktar tmur f'din il-kaxxa?

156
00:07:13,430 --> 00:07:16,000

157
00:07:16,000 --> 00:07:18,140
>> STUDENT: Il-funzjonijiet li inti sejħa.

158
00:07:18,140 --> 00:07:19,020
>> JASON Hirschhorn: Il-funzjonijiet
li nitolbu.

159
00:07:19,020 --> 00:07:20,440
U fejn ma dawn imorru?

160
00:07:20,440 --> 00:07:21,300
>> STUDENT: Fil-munzell.

161
00:07:21,300 --> 00:07:22,380
>> JASON Hirschhorn: Huma
jmorru fil-ċmieni.

162
00:07:22,380 --> 00:07:27,350
Allura aħna qed tmur biex sejħa dan
Ħaġa stabbiliti hawn il-munzell.

163
00:07:27,350 --> 00:07:31,880
U top up, aħna għandna l-borġ.

164
00:07:31,880 --> 00:07:35,450
Allura memorja mhix kaxxa biss bħal dan.

165
00:07:35,450 --> 00:07:37,330
Iżda huwa attwalment pjuttost simili.

166
00:07:37,330 --> 00:07:40,840
Huwa ser jkun hemm ħafna ta 'kaxxi fuq
u aktar, jiddependi fuq kemm hu kbir tiegħek

167
00:07:40,840 --> 00:07:43,730
kompjuter huwa jew kif big memorja tiegħek.

168
00:07:43,730 --> 00:07:46,950
>> Fil-kwotazzjoni-unquote "qiegħ"
huwa l-munzell.

169
00:07:46,950 --> 00:07:50,880
U hemm affarijiet multipli
li jmorru fuq il-munzell.

170
00:07:50,880 --> 00:07:53,840
U dawk jiddependu fuq il-funzjonijiet
għandek fil-kodiċi tiegħek.

171
00:07:53,840 --> 00:07:57,780
Inti dejjem ikollhom funzjoni waħda fil tiegħek
kodiċi imsejjaħ prinċipali, hekk dejjem hemm

172
00:07:57,780 --> 00:08:00,480
taqsima stabbiliti hawn fil-
munzell iddedikat għal main.

173
00:08:00,480 --> 00:08:03,980
>> Dawn is-sezzjonijiet fil-munzell
huma msejħa frames munzell.

174
00:08:03,980 --> 00:08:09,580
Meta inti sejħa funzjoni oħra, jgħidu prinċipali
jitlob funzjoni tfittxija binarju,

175
00:08:09,580 --> 00:08:11,075
nitfgħu frame ieħor fuq il-munzell.

176
00:08:11,075 --> 00:08:13,830

177
00:08:13,830 --> 00:08:17,320
B'mod aktar speċifiku, aħna ser
jiddonaw blokki ta 'memorja fuq tagħna

178
00:08:17,320 --> 00:08:22,960
kompjuter li jaħżen binarju tfittxija Lokali
varjabbli u biex imexxu l-binarju

179
00:08:22,960 --> 00:08:24,150
kodiċi tfittxija.

180
00:08:24,150 --> 00:08:26,810
>> Allura aħna sejħa tfittxija binarja.

181
00:08:26,810 --> 00:08:30,440

182
00:08:30,440 --> 00:08:33,340
F'dan blokki ta 'memorja, aħna qed tmur
li jaħżen varjabbli lokali tagħha.

183
00:08:33,340 --> 00:08:35,270
Aħna ser taħżen sejħiet printf tagħha.

184
00:08:35,270 --> 00:08:38,159
Jiġri x'jiġri, din il-funzjoni hija
ser jiġi maħżun hemm dritt.

185
00:08:38,159 --> 00:08:40,350
Tfittxija binarja se tesegwixxi.

186
00:08:40,350 --> 00:08:42,210
Huwa ser jitlesta eżekuzzjoni.

187
00:08:42,210 --> 00:08:47,450
X'inhu l-kelma C li ifisser
li funzjoni għandha

188
00:08:47,450 --> 00:08:49,306
tlesti l-eżekuzzjoni tiegħu?

189
00:08:49,306 --> 00:08:50,040
>> STUDENT: Ritorn.

190
00:08:50,040 --> 00:08:50,870
>> JASON Hirschhorn: Ritorn.

191
00:08:50,870 --> 00:08:53,230
Allura meta tara stqarrija ritorn,
it-trufijiet tal-funzjoni

192
00:08:53,230 --> 00:08:54,350
meta hits dak.

193
00:08:54,350 --> 00:08:56,740
Tfittxija Allura binarja se tolqot ir-ritorn tiegħu.

194
00:08:56,740 --> 00:09:01,360
Din il-parti tal-memorja essenzjalment se
jiġi lliberat.

195
00:09:01,360 --> 00:09:03,510
U prinċipali se jmorru lura għall-eżekuzzjoni.

196
00:09:03,510 --> 00:09:07,240
Allura ewlenija se nieqaf kull fejn kien, sejħa
tfittxija binarja, nikseb xi valur tar-ritorn,

197
00:09:07,240 --> 00:09:08,700
u tkompli l-eżekuzzjoni.

198
00:09:08,700 --> 00:09:10,840
Dan il-qafas munzell ser imorru.

199
00:09:10,840 --> 00:09:14,810
>> Jekk nagħmlu sejħa funzjoni jirrikorri, li
hija funzjoni li jitlob huwa stess fuq

200
00:09:14,810 --> 00:09:18,480
u aktar, nistgħu jiksbu - jgħidu aħna
għamlet tfittxija binarja recursively.

201
00:09:18,480 --> 00:09:21,520
Aħna tista 'tikseb binarja tfittxija verżjoni waħda,
tfittxija binarja tnejn, tfittxija binarja

202
00:09:21,520 --> 00:09:24,090
tlieta, tfittxija binarja erba,
tfittxija binarja ħamsa.

203
00:09:24,090 --> 00:09:27,950
U allura dan tfittxija binarja finali ħamsa
se tolqot il-każ bażi, u l-munzell

204
00:09:27,950 --> 00:09:31,010
frames se jmorru lura u jżomm għeluq
sakemm aħna terġa 'lura għall prinċipali.

205
00:09:31,010 --> 00:09:32,530
Aħna tista 'tmur fuq recursion fil-daqsxejn.

206
00:09:32,530 --> 00:09:35,530
Iżda dan kollu huwa li jgħidu, jekk int
ssejjaħ funzjonijiet multipli fi żmien,

207
00:09:35,530 --> 00:09:39,250
se jkun hemm xi stack multipli
frames fuq il-munzell.

208
00:09:39,250 --> 00:09:42,900
>> -Borġ, min-naħa l-oħra, sa
hawnhekk, mhuwiex għall-funzjonijiet,

209
00:09:42,900 --> 00:09:44,380
mhux għall varjabbli lokali.

210
00:09:44,380 --> 00:09:48,920
Huwa għal dinamikament allokati
varjabbli.

211
00:09:48,920 --> 00:09:57,210
Allura dawn huma varjabbli li jistgħu jiġu
initialized jew fil prinċipali jew

212
00:09:57,210 --> 00:09:58,640
funzjoni li jitlob prinċipali.

213
00:09:58,640 --> 00:10:00,790
Kullimkien fil-kodiċi tiegħek, dawn
jistgħu jiġu initialized.

214
00:10:00,790 --> 00:10:04,360
U biex initialize dinamikament
varjabbli allokata.

215
00:10:04,360 --> 00:10:06,970
Liema funzjoni C do nużaw?

216
00:10:06,970 --> 00:10:07,600
>> STUDENT: malloc.

217
00:10:07,600 --> 00:10:09,240
>> JASON Hirschhorn: malloc.

218
00:10:09,240 --> 00:10:10,800
Inti sejħa malloc.

219
00:10:10,800 --> 00:10:12,260
Ikollok spazju ta 'memorja.

220
00:10:12,260 --> 00:10:15,020
U dak l-ispazju tal-memorja
huwa fuq il-borġ.

221
00:10:15,020 --> 00:10:18,840
U dak l-ispazju tal-memorja soġġorni
hemm sakemm inti sejħa ħielsa.

222
00:10:18,840 --> 00:10:22,670
>> Varjabbli Allura dinamikament allokati fl-
borġ ser jeżistu sakemm inti

223
00:10:22,670 --> 00:10:25,250
tixtieq li jeżistu, u dawn mhux se
imorru sakemm inti espliċitament

224
00:10:25,250 --> 00:10:26,760
jgħidulhom li jmorru lil hinn.

225
00:10:26,760 --> 00:10:29,670
Tista 'toħloq lilhom fil-funzjoni waħda.

226
00:10:29,670 --> 00:10:31,930
Munzell dik il-funzjoni tal-
qafas ser imorru.

227
00:10:31,930 --> 00:10:35,490
Iżda dak il-varjabbli xorta se jeżistu
fil-borġ sakemm jiġi meħlus,

228
00:10:35,490 --> 00:10:39,650
potenzjalment mill-funzjoni li tissejjaħ
tfittxija binarja jew kwalunkwe.

229
00:10:39,650 --> 00:10:42,580
>> Allura dawk il-varjabbli borġ jibqgħu hemm
sakemm inti tixtieq

230
00:10:42,580 --> 00:10:43,490
li jibqgħu hemm.

231
00:10:43,490 --> 00:10:46,090
U huma jiksbu jitqiegħdu hawn.

232
00:10:46,090 --> 00:10:47,450
U allura l-waħda li jmiss gets stabbiliti hemmhekk.

233
00:10:47,450 --> 00:10:50,210
Huma jżommu jkollna mimlija, u dawn
jibqgħu hemm sakemm inti sejħa ħielsa.

234
00:10:50,210 --> 00:10:52,870
>> U essenzjalment, il-borġ u l-munzell,
jkollna għall-mistoqsija Marcus, il-

235
00:10:52,870 --> 00:10:54,500
jikbru lejn xulxin.

236
00:10:54,500 --> 00:10:57,730
U jekk dawn run fis xulxin, inti stajt
użati kollha tal-memorja fil tiegħek

237
00:10:57,730 --> 00:11:01,330
kompjuter, u l-programm tiegħek se nieqaf
għaliex inti ma għandekx xi memorja aktar

238
00:11:01,330 --> 00:11:02,420
xellug għall-użu.

239
00:11:02,420 --> 00:11:07,290
Bejniethom, hemm
affarijiet potenzjalment oħra.

240
00:11:07,290 --> 00:11:10,980
Iżda għall-iskop ta 'dan il-kors, inti
ma bżonn ninkwetaw dwar dan.

241
00:11:10,980 --> 00:11:12,020
>> Allura li kien ir-risposta
għall-mistoqsija tiegħek.

242
00:11:12,020 --> 00:11:13,520
Tinkwetax dwar dan.

243
00:11:13,520 --> 00:11:15,550
Iżda dan kien ir-risposta twil.

244
00:11:15,550 --> 00:11:17,800
Kulma għandek bżonn tkun taf l-
borġ u l-munzell se -

245
00:11:17,800 --> 00:11:18,900
wieħed jibda fil-qiegħ.

246
00:11:18,900 --> 00:11:19,570
Il-munzell ma.

247
00:11:19,570 --> 00:11:20,790
-Borġ huwa up hemm.

248
00:11:20,790 --> 00:11:21,990
Huma se jikbru lejn xulxin.

249
00:11:21,990 --> 00:11:23,110
>> U jekk huma jmissu, li l-problema.

250
00:11:23,110 --> 00:11:24,500
Inti dam barra ta 'memorja.

251
00:11:24,500 --> 00:11:28,760
Iżda wkoll, minbarra jafu fejn
huma, dak li hija maħżuna kemm fil-

252
00:11:28,760 --> 00:11:30,512
munzell u borġ.

253
00:11:30,512 --> 00:11:31,410
Curtis.

254
00:11:31,410 --> 00:11:33,570
>> CURTIS: Meta jikkonfliġġu,
hija li overflow munzell?

255
00:11:33,570 --> 00:11:35,670
>> JASON Hirschhorn: Meta jikkonfliġġu,
li mhux overflow munzell.

256
00:11:35,670 --> 00:11:38,340
A overflow munzell hija żona differenti
li nistgħu jmorru fuq jekk inti tixtieq li.

257
00:11:38,340 --> 00:11:40,020
OK, aħna ser terga 'lura għal dik fil-daqsxejn.

258
00:11:40,020 --> 00:11:42,730
>> STUDENT: X'inhu l-kelma imsejjaħ
meta hit xulxin, il-

259
00:11:42,730 --> 00:11:44,450
munzell u l-borġ?

260
00:11:44,450 --> 00:11:46,640
>> JASON Hirschhorn: Għal issa,
ma joqogħdu jinkwetaw dwar.

261
00:11:46,640 --> 00:11:47,750
Just know -

262
00:11:47,750 --> 00:11:50,530
I se twieġeb din id-domanda
wara klassi.

263
00:11:50,530 --> 00:11:52,680
Jekk dawn run fis xulxin, inti spiċċaw
tal-memorja, għaliex hemm aktar

264
00:11:52,680 --> 00:11:53,330
ispazju hemmhekk.

265
00:11:53,330 --> 00:11:55,450
>> STUDENT: Jiddispjacini, x'hemm tort seg?

266
00:11:55,450 --> 00:11:58,710
>> JASON Hirschhorn: A segment
tort jistgħu jissejħu għal -

267
00:11:58,710 --> 00:12:02,240
dan jiddependi għaliex imsejjaħ il tort seg tal.

268
00:12:02,240 --> 00:12:06,260
Kultant, overflow munzell tiegħek, inneħħu
jgħidu seg tort bħala l-iżball.

269
00:12:06,260 --> 00:12:08,180
>> STUDENT: What about dereferencing
varjabbli null?

270
00:12:08,180 --> 00:12:10,040
Huwa li tort seg?

271
00:12:10,040 --> 00:12:11,480
>> JASON Hirschhorn: Dereferencing
pointer null -

272
00:12:11,480 --> 00:12:17,850
OK, hekk jekk ikollok pointer li inti
daqs l null, pointers, recall,

273
00:12:17,850 --> 00:12:20,270
indirizzi store memorja
bħala valuri tagħhom.

274
00:12:20,270 --> 00:12:23,660
U pointer null huwa essenzjalment
ħażna 0, 0-th

275
00:12:23,660 --> 00:12:26,670
indirizzati f'dik varjabbli.

276
00:12:26,670 --> 00:12:30,010
Allura 0x, 0, 0, 0, 0, eċċetera.

277
00:12:30,010 --> 00:12:35,030
Dan indirizz 0-th fil-memorja li mhux
fl-istampa tagħna, dan huwa up hemm

278
00:12:35,030 --> 00:12:38,800
x'imkien, thats riżervati
għall-kompjuter.

279
00:12:38,800 --> 00:12:40,130
Aħna ma jitħallew tmiss.

280
00:12:40,130 --> 00:12:44,680
>> Allura meta program tiegħek ta 'eżekuzzjoni, jekk
xi ħaġa hija tipprova tmur għall-memorja

281
00:12:44,680 --> 00:12:48,990
indirizz 0, huwa jaf li
li hu valur vojt.

282
00:12:48,990 --> 00:12:50,820
Huwa jaf xejn m'għandu jkun hemm.

283
00:12:50,820 --> 00:12:53,420
Mela jekk inti tipprova u l-użu xi ħaġa hemmhekk
u jittrattaw xi ħaġa simili hemmhekk jew

284
00:12:53,420 --> 00:12:58,355
tipprova tmur f'dak il-post, int
se tikseb tort seg jew żball.

285
00:12:58,355 --> 00:13:00,520
Does li iwieġeb il-mistoqsija tiegħek?

286
00:13:00,520 --> 00:13:03,170
>> U issa aħna ser imorru lura
munzell overflow.

287
00:13:03,170 --> 00:13:09,560
Affarijiet fil-munzell, kif inti guys jkollhom
rajna qabel, fil - ejja jiġbed qrib

288
00:13:09,560 --> 00:13:11,966
twaqqif ta 'qafas munzell.

289
00:13:11,966 --> 00:13:15,050
Jista kulħadd tara li?

290
00:13:15,050 --> 00:13:16,650
Allura aħna għandna frame munzell tagħna.

291
00:13:16,650 --> 00:13:23,260
Aħna qed iffrankar firxa fil bħala lokali
varjabbli f'dan il-funzjoni.

292
00:13:23,260 --> 00:13:29,510
Allura ngħid firxa tagħna għandha ħames spots.

293
00:13:29,510 --> 00:13:33,230
Il-ħames dawk ser tkun maħżuna
f'dak il-qafas munzell.

294
00:13:33,230 --> 00:13:37,540
>> Jekk nibdew bil-miktub lil hinn mill-
limiti ta 'din array -

295
00:13:37,540 --> 00:13:43,990
hekk jekk nibdew bil-miktub fi,
ejja ngħidu li għamilhom 0.

296
00:13:43,990 --> 00:13:46,800
Dawk huma l-ħames indiċi
ta 'firxa tagħna.

297
00:13:46,800 --> 00:13:50,980
Jekk nibdew bil-miktub fis indiċi 5, li
aħna ma jkollhomx meta għandna

298
00:13:50,980 --> 00:13:55,900
firxa ta 'daqs 5, nibdew bil-miktub fi
indiċi 6, 7, 8, 9, nistgħu jiksbu munzell

299
00:13:55,900 --> 00:13:57,960
Żball overflow.

300
00:13:57,960 --> 00:14:00,510
>> Ġeneralment mhuwiex -

301
00:14:00,510 --> 00:14:04,910
inti probabilment se tikseb fis-problemi
jekk inti tmur fuq waħda.

302
00:14:04,910 --> 00:14:08,640
Iżda ġeneralment, inti se tikseb fis-
inkwiet aktar jekk inti tmur fuq minn lott

303
00:14:08,640 --> 00:14:12,770
u inti tmur s'issa fuq li tikteb
fuq l-indirizz ta 'ritorn ta' dak

304
00:14:12,770 --> 00:14:16,080
funzjoni, li jinsab fil-
qiegħ tal-qafas munzell.

305
00:14:16,080 --> 00:14:16,520
>> Minħabba, right?

306
00:14:16,520 --> 00:14:17,670
You - fil-- sorry.

307
00:14:17,670 --> 00:14:18,550
Mhux "għaliex id-dritt."

308
00:14:18,550 --> 00:14:20,470
>> Fil-qafas munzell, inti għandek
varjabbli lokali tiegħek.

309
00:14:20,470 --> 00:14:27,090
Fil-qiegħ nett tal-munzell
qafas huwa l-indirizz ta 'ritorn.

310
00:14:27,090 --> 00:14:28,790
Li meta l-funzjoni
tmur meta huwa fuq.

311
00:14:28,790 --> 00:14:33,750
U jekk inti jissostitwixxu li r-ritorn
indirizz, allura meta dan il-qafas munzell,

312
00:14:33,750 --> 00:14:36,680
meta inti qed tmur permezz tal-munzell
frejm u eżekuzzjoni ta 'kull linja, int

313
00:14:36,680 --> 00:14:40,350
se jmorru lill-indirizz tiegħek ritorn ġdida
thats miktub hemm minflok il-

314
00:14:40,350 --> 00:14:40,910
wieħed attwali.

315
00:14:40,910 --> 00:14:45,050
U li kif aħna stajt tidher
xi ksur tas-sigurtà

316
00:14:45,050 --> 00:14:46,780
jista 'jiġri ma' kompjuters.

317
00:14:46,780 --> 00:14:52,760
>> Overflow hekk munzell, fil-qosor, huwa meta
inti jissostitwixxu l-parti fil-ċmieni

318
00:14:52,760 --> 00:14:55,440
int suppost għall-użu, il lokali
varjabbli int suppost biex jintużaw, u

319
00:14:55,440 --> 00:14:58,070
b'mod partikolari meta tibda kitba fuq
affarijiet importanti bħall-

320
00:14:58,070 --> 00:14:59,100
indirizz ritorn.

321
00:14:59,100 --> 00:15:00,090
U li fejn int ser tingħata żball.

322
00:15:00,090 --> 00:15:03,980
Jew forsi anke inti tista 'tibda
anke bil-miktub fis -

323
00:15:03,980 --> 00:15:05,370
jgħidu tfittxija binarja kien
dritt fuq prinċipali.

324
00:15:05,370 --> 00:15:07,790
Jekk inti overwrote ħafna, inti
tista 'tikteb fi prinċipali.

325
00:15:07,790 --> 00:15:10,230
Iżda ġeneralment, ikollok żball qabel
imbagħad, minħabba li l-kompjuter jaf

326
00:15:10,230 --> 00:15:12,270
int qed tagħmel xi ħaġa inti
ma għandha tkun qiegħda tagħmel.

327
00:15:12,270 --> 00:15:12,560
Yeah.

328
00:15:12,560 --> 00:15:13,910
>> STUDENT: X'hemm differenza
bejn overflow munzell

329
00:15:13,910 --> 00:15:16,940
u overflow buffer?

330
00:15:16,940 --> 00:15:19,420
>> JASON Hirschhorn: overflow buffer
huwa tip aktar ġeneriku ta '

331
00:15:19,420 --> 00:15:20,395
dak li stajt biss deskritti.

332
00:15:20,395 --> 00:15:22,610
>> STUDENT: Allura overflow munzell hija
Eżempju ta 'overflow buffer.

333
00:15:22,610 --> 00:15:23,420
>> JASON Hirschhorn: Eżattament.

334
00:15:23,420 --> 00:15:28,700
Dan huwa firxa nistgħu jaħsbu bħala
buffer, spazju għall-affarijiet li jmorru pulzieri

335
00:15:28,700 --> 00:15:30,600
Din hija overflow buffer munzell.

336
00:15:30,600 --> 00:15:33,210
Jista 'jkollna overflow buffer borġ.

337
00:15:33,210 --> 00:15:36,870
Jekk kien hemm buffer, li hemm ħafna drabi
huwa firxa l-borġ, u aħna

338
00:15:36,870 --> 00:15:40,600
overwrote dawk limiti, allura aħna kieku
jkollhom overflow buffer borġ.

339
00:15:40,600 --> 00:15:44,870
>> U lil hinn mill-ambitu ta 'dan il-kors,
dawn qed skoperti daqsxejn differenti.

340
00:15:44,870 --> 00:15:48,040
Il-kompilatur għandha speċjali
modi ta 'sejbien kull.

341
00:15:48,040 --> 00:15:50,660
Iżda overflow buffer huwa aktar ġeneriku
tip ta 'dak I deskritt,

342
00:15:50,660 --> 00:15:54,090
li kienet overflow buffer munzell.

343
00:15:54,090 --> 00:15:56,240
Did li iwieġeb il-mistoqsija tiegħek?

344
00:15:56,240 --> 00:15:57,910
Sweet.

345
00:15:57,910 --> 00:16:01,850
>> Kien hemm xi mistoqsijiet oħra relatati
għall-ċumnija jew il-munzell?

346
00:16:01,850 --> 00:16:04,920

347
00:16:04,920 --> 00:16:05,510
Yeah.

348
00:16:05,510 --> 00:16:08,220
>> STUDENT: Naf li inti għandek kordi ħielsa
għaliex qed fil-borġ

349
00:16:08,220 --> 00:16:09,305
u inti ma tridx tnixxija memorja.

350
00:16:09,305 --> 00:16:12,240
Imma għandek biex ħielsa varjabbli globali
u għalf bħal dik?

351
00:16:12,240 --> 00:16:14,335
Jew huma meħlusa awtomatikament?

352
00:16:14,335 --> 00:16:15,700
>> JASON Hirschhorn: Good kwistjoni.

353
00:16:15,700 --> 00:16:22,340
Għalhekk fl CS50.H, noħolqu dan il-ħaġa
għalik imsejħa string.

354
00:16:22,340 --> 00:16:23,800
A string huwa verament dak?

355
00:16:23,800 --> 00:16:24,810
>> STUDENT: Char star.

356
00:16:24,810 --> 00:16:29,180
>> JASON Hirschhorn: A star char, a pointer
għal karattru, a pointer biex

357
00:16:29,180 --> 00:16:30,650
firxa ta 'karattri.

358
00:16:30,650 --> 00:16:32,210
Dak hu l-sekwenza huwa.

359
00:16:32,210 --> 00:16:36,050
Għalhekk għandna bżonn biex ħielsa, għax
getstring, li aħna użati ħafna -

360
00:16:36,050 --> 00:16:38,370
isem string ugwali getstring -

361
00:16:38,370 --> 00:16:43,560
li mallocs għalina xi memorja fuq il-
borġ u mbagħad jirritorna pointer għall-

362
00:16:43,560 --> 00:16:47,230
ewwel karattru ta 'dak
spag, stilla char.

363
00:16:47,230 --> 00:16:52,760
>> Allura apparentement, jekk inti ma ġewx
miktub ħielsa fuq kwalunkwe kordi tiegħek

364
00:16:52,760 --> 00:16:55,600
li ħadthom imsejħa s'issa, ikollok
ġie jnixxu xi memorja.

365
00:16:55,600 --> 00:16:57,430
Of course aħna ma tkellem dwar
dan, sabiex ħadd gotten

366
00:16:57,430 --> 00:16:58,520
inkwiet biex isir dan.

367
00:16:58,520 --> 00:16:59,980
Imma jmorru quddiem, iva.

368
00:16:59,980 --> 00:17:03,990
Meta inti sejħa getstring, int
mallocing xi spazju fuq il-borġ.

369
00:17:03,990 --> 00:17:07,640
U jekk inti ma sejħa ħielsa aktar tard li
spag, inti għandek nixxija memorja.

370
00:17:07,640 --> 00:17:09,440
Li iwieġeb il-mistoqsija tiegħek?

371
00:17:09,440 --> 00:17:10,606
>> Yeah

372
00:17:10,606 --> 00:17:15,020
>> STUDENT: Allura biex tagħmel dan, do nużaw
dritt b'xejn qabel ir-ritorn?

373
00:17:15,020 --> 00:17:18,510
Bħal, fl-ambitu ta ', I raden jekk
ngħidu, bħal, int prinċipali, fil-

374
00:17:18,510 --> 00:17:24,410
ambitu tal-kodiċi li huwa fi ħdan dawk
braces kaboċċi, dritt qabel -

375
00:17:24,410 --> 00:17:26,140
inti taf fejn youd
ġeneralment jitpoġġa ritorn.

376
00:17:26,140 --> 00:17:27,950
Do inti tpoġġi ħielsa qabel dik?

377
00:17:27,950 --> 00:17:31,000
>> JASON Hirschhorn: Allura inti tista 'tpoġġi b'xejn
fejn inti tixtieq li tqiegħed ħielsa.

378
00:17:31,000 --> 00:17:33,810
Minħabba li dawn huma dinamikament allokati
varjabbli, għaliex dawn jistgħu

379
00:17:33,810 --> 00:17:39,170
jgħixu lil hinn mill-ambitu ta 'partikolari
funzjoni, jekk inti sejħa malloc fil-

380
00:17:39,170 --> 00:17:44,140
funzjoni separata ta ', per eżempju,
getstring, inti tista 'sejħa ħielsa prinċipali.

381
00:17:44,140 --> 00:17:46,050
Inti ma għandekx bżonn li hija sejħa
fil-funzjoni speċifika

382
00:17:46,050 --> 00:17:47,570
fejn malloc huwa msejjaħ.

383
00:17:47,570 --> 00:17:50,340
Imma inti jeħtieġ li hija sejħa
qabel prospetti prinċipali.

384
00:17:50,340 --> 00:17:51,120
>> U huwa verament jiddependi.

385
00:17:51,120 --> 00:17:54,960
Hija tiddependi fuq għaliex inti malloced li
ispazju fl-ewwel post.

386
00:17:54,960 --> 00:17:57,320
Xi nies se sejħa
ħielsa pretty malajr.

387
00:17:57,320 --> 00:17:59,220
Xi nies mhux se sejħa ħielsa sakemm
l-aħħar tal-programm tagħhom.

388
00:17:59,220 --> 00:18:00,660
U dawn ser jgħaddu
u kollox ħielsa.

389
00:18:00,660 --> 00:18:03,597
Hija tiddependi fuq għaliex inti imsejħa malloc.

390
00:18:03,597 --> 00:18:11,270
>> STUDENT: U tghid
jekk inti imsejħa użu getstring?

391
00:18:11,270 --> 00:18:13,320
You jgħidu ħielsa liema?

392
00:18:13,320 --> 00:18:20,040
>> JASON Hirschhorn: Allura l-sintassi b'xejn
hija sempliċement ħielsa, paren miftuħa, qrib

393
00:18:20,040 --> 00:18:22,130
paren, u l-isem tal-pointer.

394
00:18:22,130 --> 00:18:26,410
Mela jekk inti tikteb ugwali isem string
getstring, inti tpoġġi l-isem fil hawn.

395
00:18:26,410 --> 00:18:27,760
Dik hija l-isem tal-pointer.

396
00:18:27,760 --> 00:18:30,570
U taf li hija ħielsa li l-memorja.

397
00:18:30,570 --> 00:18:33,920
>> STUDENT: Allura meta jillibera li l-memorja,
il-pointer għadu punti li dak il-post

398
00:18:33,920 --> 00:18:34,970
fil-memorja?

399
00:18:34,970 --> 00:18:39,020
Jew huwa l-pointer żvojtati wkoll
l-indirizz li hija tirreferi għall.

400
00:18:39,020 --> 00:18:40,290
>> JASON Hirschhorn: Aħna għandhom jippruvaw li.

401
00:18:40,290 --> 00:18:41,430
Għandna kodiċi li.

402
00:18:41,430 --> 00:18:43,880
Ejja terga 'lura meta nikbru biex
kodifikazzjoni, u ejja kodiċi li.

403
00:18:43,880 --> 00:18:46,000
U jekk inti tixtieq li insemmu l-risposta
għal dan, inti tista 'wkoll kodiċi li

404
00:18:46,000 --> 00:18:46,690
fil-frattemp.

405
00:18:46,690 --> 00:18:49,100
Iżda li l-kwistjoni kbira.

406
00:18:49,100 --> 00:18:53,480
>> STUDENT: Huwa possibbli li
xi ħaġa b'xejn wisq malajr?

407
00:18:53,480 --> 00:18:58,530
Allura inti xorta bżonnha għall-programm tiegħek,
u inti meħlusa dak l-ispazju memorja?

408
00:18:58,530 --> 00:18:59,200
>> JASON Hirschhorn: Iva.

409
00:18:59,200 --> 00:19:03,020
Huwa possibbli, jekk inti xi ħaġa b'xejn
u mbagħad tuża mill-ġdid, inti se

410
00:19:03,020 --> 00:19:06,890
run fis żball.

411
00:19:06,890 --> 00:19:10,810
Imma dak li fuqek, għaliex inti meħlusa
xi ħaġa u mbagħad sejjaħ aktar tard.

412
00:19:10,810 --> 00:19:13,940
Allura li kien żball ta 'programmer.

413
00:19:13,940 --> 00:19:14,780
Imma iva.

414
00:19:14,780 --> 00:19:17,760
Inti tista 'tikteb dak.

415
00:19:17,760 --> 00:19:19,240
>> Kwalunkwe mistoqsijiet aktar fuq -

416
00:19:19,240 --> 00:19:19,760
iva.

417
00:19:19,760 --> 00:19:22,820
>> STUDENT: Mela jekk inti suppost biss
ħielsa fil ġenerali qabel l-

418
00:19:22,820 --> 00:19:25,490
programm jintemm, ma jfissirx li jekk l-
programm jintemm u inti ma ħielsa it-

419
00:19:25,490 --> 00:19:27,580
li l-memorja għadu allokat?

420
00:19:27,580 --> 00:19:31,330
>> JASON Hirschhorn: Jekk programm tiegħek truf
u tinsa biex ħielsa xi ħaġa, allura

421
00:19:31,330 --> 00:19:34,390
li l-memorja ġie allokat matul
il-ħajja tal-programm tiegħek.

422
00:19:34,390 --> 00:19:37,670
Meta program tiegħek jagħlaq kompletament,
li l-memorja mhux se

423
00:19:37,670 --> 00:19:39,490
li jibqa 'hemm għal dejjem.

424
00:19:39,490 --> 00:19:42,080
Il-kompjuter huwa intelliġenti biżżejjed biex tkun taf
li meta l-programm jagħlaq, huwa

425
00:19:42,080 --> 00:19:46,440
għandu jeħles kollha tal-memorja li
kienet assoċjata ma 'dak il-programm.

426
00:19:46,440 --> 00:19:51,240
>> Madankollu, hemm għodda inti tista 'taħdem
fuq programm biex tiskopri jekk, meta l-

427
00:19:51,240 --> 00:19:54,720
programm lest, inti nesa
biex ħielsa xi memorja.

428
00:19:54,720 --> 00:19:57,960
U għall-problema li jmiss tiegħek stabbilit fejn
inti ser tkun qed tuża malloc u l-użu

429
00:19:57,960 --> 00:20:02,610
pointers, inti ser tkun qed taħdem din
programm dwar il-programm tiegħek biex tara jekk,

430
00:20:02,610 --> 00:20:06,530
meta jerġa prinċipali, kellek xi
affarijiet li tħallew unfreed.

431
00:20:06,530 --> 00:20:09,130
>> Allura dawn mhux qed tmur toqgħod malloced
dejjem fil-kompjuter tiegħek.

432
00:20:09,130 --> 00:20:11,720
Dan ikun ħela, minħabba
malajr ħafna, kompjuters

433
00:20:11,720 --> 00:20:12,960
jaħarbux mill-memorja.

434
00:20:12,960 --> 00:20:16,450
Iżda jekk dawn jimxu sa l-aħħar ta 'tiegħek
programm u dawn mhux qed lliberat u tiegħek

435
00:20:16,450 --> 00:20:20,260
programm ħruġ, li għadha problema
li din l-għodda se jgħinek tindirizza.

436
00:20:20,260 --> 00:20:21,520
>> STUDENT: Huwa li Valgrind?

437
00:20:21,520 --> 00:20:22,910
>> JASON Hirschhorn: Huwa
imsejħa Valgrind.

438
00:20:22,910 --> 00:20:23,520
U tkun taf tkun -

439
00:20:23,520 --> 00:20:25,780
>> STUDENT: Iżda aħna ma għandekx tkun taf
li għall-kwizz, għalkemm?

440
00:20:25,780 --> 00:20:27,600
I mean, kien tkellem dwar
ftit fil-lecture.

441
00:20:27,600 --> 00:20:33,600
>> JASON Hirschhorn: So Valgrind
huwa l-isem ta 'dik l-għodda.

442
00:20:33,600 --> 00:20:37,180
Jafu dak li ma huwa
biżżejjed għall-kwizz.

443
00:20:37,180 --> 00:20:40,200
Imma int ma użati encore fuq tiegħek
problema stabbiliti għaliex aħna ma kellhomx

444
00:20:40,200 --> 00:20:43,520
sett problema li tkun ittrattati b'mod espliċitu
ma malloc jew inti tuża malloc.

445
00:20:43,520 --> 00:20:45,330
Allura int ma użati Valgrind s'issa.

446
00:20:45,330 --> 00:20:47,760
Iżda inti se tuża dan qabel
milli iktar tard.

447
00:20:47,760 --> 00:20:48,710
>> STUDENT: Tista jirrepetu
dak Valgrind hu?

448
00:20:48,710 --> 00:20:49,190
>> JASON Hirschhorn: Jiddispjacini?

449
00:20:49,190 --> 00:20:51,240
>> STUDENT: Tista jirrepetu dak
l-għan ta 'Valgring hu?

450
00:20:51,240 --> 00:20:53,100
>> JASON Hirschhorn: Valgrind
huwa l-isem -

451
00:20:53,100 --> 00:20:59,890
bħal GDB jgħinek debug program tiegħek,
Valgrind jgħinek insemmu jekk

452
00:20:59,890 --> 00:21:03,210
affarijiet ma jkunux ġew meħlusa
meta program tiegħek jagħlaq.

453
00:21:03,210 --> 00:21:05,110
Allura inti ser run fuq program tiegħek.

454
00:21:05,110 --> 00:21:09,230
U l-programm tiegħek ħruġ, u inneħħu jgħidu
program tiegħek imsejħa malloc dan ħafna

455
00:21:09,230 --> 00:21:13,670
darbiet għal dan ħafna bytes, u inti
biss imsejħa free dan ħafna drabi.

456
00:21:13,670 --> 00:21:16,520
U għalhekk inti xellug dawn ħafna bytes
mingħajr ma jkunu meħlusa.

457
00:21:16,520 --> 00:21:18,050
Jew ser jgħidu li inti stajt meħlusa kollox.

458
00:21:18,050 --> 00:21:19,070
Tajba tax-xogħol.

459
00:21:19,070 --> 00:21:19,480
>> STUDENT: OK.

460
00:21:19,480 --> 00:21:21,060
U huwa msejjaħ Valgring?

461
00:21:21,060 --> 00:21:24,940
>> JASON Hirschhorn: V-A-L-G-R-I-N-D.

462
00:21:24,940 --> 00:21:25,970
>> STUDENT: A mistoqsija dwar pointers.

463
00:21:25,970 --> 00:21:30,080
Allura ngħid għandek n istilla
x ugwali xi ħaġa.

464
00:21:30,080 --> 00:21:33,330
Li jkun daqs, tkun xi tkun int tqegħid
hemm, li dak li qed jitpoġġew ġewwa

465
00:21:33,330 --> 00:21:36,120
dak x hija li tipponta lejn,
jew il-pointer ta 'x?

466
00:21:36,120 --> 00:21:37,690
>> JASON Hirschhorn: Can You
irrepeti l-kwistjoni?

467
00:21:37,690 --> 00:21:39,340
Nistgħu niġbdu waqt li inti jgħidu li?

468
00:21:39,340 --> 00:21:42,710
>> STUDENT: Fil-kwizz, fil-fatt, il-
waħda inti mibgħut lilna, kien simili, char

469
00:21:42,710 --> 00:21:46,520
verità star ugwali blat CS50, right?

470
00:21:46,520 --> 00:21:52,190
Allura dan ifisser li li blat CS50
huwa dak li l-verità hija li tipponta lejn?

471
00:21:52,190 --> 00:21:55,810
>> JASON Hirschhorn: Allura inti qed jitkellem
dwar stilla char fil string, kif

472
00:21:55,810 --> 00:21:56,460
li x-xogħlijiet?

473
00:21:56,460 --> 00:21:56,890
Yeah.

474
00:21:56,890 --> 00:21:57,700
OK.

475
00:21:57,700 --> 00:21:59,140
Ejja tiġbed hawn fuq.

476
00:21:59,140 --> 00:22:07,100
>> [Konverżazzjoni SIDE]

477
00:22:07,100 --> 00:22:11,130
>> JASON Hirschhorn: Allura dan il-varjabbli
se tkun ta 'star char tip.

478
00:22:11,130 --> 00:22:14,580
Kif big hija varjabbli
ta 'star char tip?

479
00:22:14,580 --> 00:22:15,510
Kemm bytes?

480
00:22:15,510 --> 00:22:16,450
>> STUDENTI: erba.

481
00:22:16,450 --> 00:22:18,210
>> JASON Hirschhorn: Huwa erba 'bytes.

482
00:22:18,210 --> 00:22:21,420
Kif id-drittijiet ħafna hija varjabbli
ta 'star int tip?

483
00:22:21,420 --> 00:22:22,210
>> STUDENTI: erba.

484
00:22:22,210 --> 00:22:24,910
>> JASON Hirschhorn: Erba bytes.

485
00:22:24,910 --> 00:22:28,280
Jekk huwa pointer, allura huwa dejjem
erba 'bytes, għaliex pointers, tagħhom

486
00:22:28,280 --> 00:22:30,070
valur huwa indirizz memorja.

487
00:22:30,070 --> 00:22:35,160
U l-indirizzi tal-memorja fuq il-CS50
appliance huma erba 'bytes twil.

488
00:22:35,160 --> 00:22:42,900
Allura meta aħna sejħa getstring, jew meta aħna
jiġifieri, stringname ugwali, u mbagħad

489
00:22:42,900 --> 00:22:46,140
kwotazzjonijiet doppja tpoġġi string,
aħna tqegħid -

490
00:22:46,140 --> 00:22:46,920
Ukoll, li ftit differenti.

491
00:22:46,920 --> 00:22:48,630
Aħna ser do getstring bħala eżempju.

492
00:22:48,630 --> 00:22:52,150
Jew xi ħaġa star char
huwa daqs il-sekwenza.

493
00:22:52,150 --> 00:22:54,360
Jiddispjacini, agħtini l-eżempju
li taqra?

494
00:22:54,360 --> 00:22:57,590
>> STUDENT: char verità star ugwali
"blat cs50" fil-kwotazzjonijiet doppja.

495
00:22:57,590 --> 00:23:02,260
>> JASON Hirschhorn: Allura dan il stilla, din
aħna ser sejħa dan varjabbli x għall tagħna

496
00:23:02,260 --> 00:23:04,060
għanijiet ġeneriċi.

497
00:23:04,060 --> 00:23:05,970
Imxejna ħolqot varjabbli msejħa x.

498
00:23:05,970 --> 00:23:07,610
Huwa star char tip.

499
00:23:07,610 --> 00:23:10,950
Huwa pointer għal serje
ta 'karattri.

500
00:23:10,950 --> 00:23:12,200
Allura down hawn -

501
00:23:12,200 --> 00:23:23,710

502
00:23:23,710 --> 00:23:25,890
>> Allura dan huwa kif dan seta '
jaħdmu fil-memorja.

503
00:23:25,890 --> 00:23:27,410
Dan taħżen l-indirizz tal-memorja.

504
00:23:27,410 --> 00:23:31,770
Ikun jaħżnu l-indirizz tal-memorja ta '
l-ewwel karattru fil-firxa.

505
00:23:31,770 --> 00:23:33,830
U allura meta inti segwita
il-pointer, inti

506
00:23:33,830 --> 00:23:35,200
jiksbu l-ewwel karattru.

507
00:23:35,200 --> 00:23:38,780
>> U jekk inti qed taqra dan ħaġa simili
string, il-kompjuter tiegħek huwa intelliġenti

508
00:23:38,780 --> 00:23:42,930
biżżejjed biex tkun taf, taqra dan ħaġa sħiħa
sakemm jiġrilha għal backlash 0.

509
00:23:42,930 --> 00:23:45,530
Imma jekk inti qed taqra dan karattru fi
żmien, hekk int mtennija permezz

510
00:23:45,530 --> 00:23:49,910
din is-sekwenza, allura inti se biss taqra
karattru fi żmien sakemm ikollok biex

511
00:23:49,910 --> 00:23:50,850
backslash 0.

512
00:23:50,850 --> 00:23:52,335
Dan jista 'ma twieġeb tiegħek
kwistjoni, għalkemm.

513
00:23:52,335 --> 00:23:55,610
>> STUDENT: Yeah, iżda inti għandek mhux
malloced dak l-ispazju

514
00:23:55,610 --> 00:23:58,400
għadu għal dak pointer.

515
00:23:58,400 --> 00:24:02,510
>> JASON Hirschhorn: Hekk jien ma pjuttost ċert
eżattament dak li qed tfittex fi,

516
00:24:02,510 --> 00:24:03,640
minħabba I ma tagħmel dik kwizz.

517
00:24:03,640 --> 00:24:06,370
Li suppost kellha tkun utli
riżorsi minn TF ieħor.

518
00:24:06,370 --> 00:24:11,380
Jekk inti qed joħolqu string fuq il-
munzell jew bħala varjabbli lokali, inneħħu

519
00:24:11,380 --> 00:24:16,920
jkun biss firxa ta 'piżijiet minflok
ġeneralment stilla char tipponta lejn

520
00:24:16,920 --> 00:24:18,600
string ieħor.

521
00:24:18,600 --> 00:24:20,550
Imma jien ma nafx.

522
00:24:20,550 --> 00:24:25,065
Dan jista 'jkun pointer għall-ieħor
string fuq il-munzell kif ukoll.

523
00:24:25,065 --> 00:24:27,240
Yeah.

524
00:24:27,240 --> 00:24:31,116
>> STUDENT: Naf li inti jeħtieġ li
talloka memorja jekk l-pointer huwa

525
00:24:31,116 --> 00:24:33,360
jkollna ddikjarat ġewwa
ta 'funzjoni oħra.

526
00:24:33,360 --> 00:24:36,740
Għandek bżonn biex tagħmel l-istess ħaġa jekk huwa
jiġu dikjarati ġewwa ta ewlenija,

527
00:24:36,740 --> 00:24:39,570
inti qed tużaha ġewwa tal ewlieni?

528
00:24:39,570 --> 00:24:43,590
>> JASON Hirschhorn: Allura iva.

529
00:24:43,590 --> 00:24:46,670
Tista 'tiddikjara pointer għal kwalunkwe
indirizz tal-memorja fil-memorja.

530
00:24:46,670 --> 00:24:51,440
Hija tista 'tkun l-indirizz memorja ta' lokali
varjabbli, għalkemm oftentimes,

531
00:24:51,440 --> 00:24:55,760
nies ma jiddikjarawx l-indirizzi tal-memorja
varjabbli lokali għaliex huma jmorru

532
00:24:55,760 --> 00:24:59,890
bogħod darba li funzjoni lura, li
huwa għaliex aħna ġeneralment malloc affarijiet.

533
00:24:59,890 --> 00:25:04,630
Imma iva, inti tista 'tiddikjara pointer
għal varjabbli oħra lokali.

534
00:25:04,630 --> 00:25:06,360
Huwa biss ġeneralment ma jsirx.

535
00:25:06,360 --> 00:25:09,480
Imma I tista 'tagħti ħarsa lejn dak
Ħaġa speċifiku wara klassi.

536
00:25:09,480 --> 00:25:10,650
Yeah.

537
00:25:10,650 --> 00:25:12,350
>> STUDENT: Naħseb li dan huwa tip
ta 'dak li qed jiġi mitlub.

538
00:25:12,350 --> 00:25:16,930
Dan ma jidhirx stramba li jiġu initializing
pointer mhux bħala

539
00:25:16,930 --> 00:25:20,760
indirizz, iżda bħala dak
tidher qisha valur.

540
00:25:20,760 --> 00:25:25,970
Jidher bħall-CS50 huwa x'hemm ġewwa
il-ħaġa li għandu jiġi osservat għal u

541
00:25:25,970 --> 00:25:28,820
mhux-indirizz attwali, id-dritt?

542
00:25:28,820 --> 00:25:30,520
>> JASON Hirschhorn: Allura dak
mhuwiex il-każ, għalkemm.

543
00:25:30,520 --> 00:25:32,470
Li mhux dak li qed jiġri.

544
00:25:32,470 --> 00:25:35,910
Meta inti tiddikjara stilla char,
huwa l-indirizz tal-memorja.

545
00:25:35,910 --> 00:25:38,860
Pointers huma indirizzi kollha tal-memorja
tipponta lejn xi ħaġa oħra.

546
00:25:38,860 --> 00:25:41,480
Li xi ħaġa oħra jista 'jkun fuq il-
munzell, iżda kważi dejjem fuq il-

547
00:25:41,480 --> 00:25:43,440
borġ fil-mod aħna se jarawha użat.

548
00:25:43,440 --> 00:25:46,860

549
00:25:46,860 --> 00:25:53,500
Iżda stringname ugwali double-kwotazzjoni
"Getstring," nistgħu naraw li u aħna

550
00:25:53,500 --> 00:25:55,010
tista 'tfittex permezz ta' dak u kodiċi li.

551
00:25:55,010 --> 00:26:01,190
getstring string mhux qed ffrankat
dak il-varjabbli, jew kull string

552
00:26:01,190 --> 00:26:04,580
isem huwa mhux qed salvati f'dak
varjabbli, għaliex li mhux kif

553
00:26:04,580 --> 00:26:06,070
pointers jaħdmu.

554
00:26:06,070 --> 00:26:06,770
Does li jagħmel sens?

555
00:26:06,770 --> 00:26:07,170
>> STUDENT: Yeah.

556
00:26:07,170 --> 00:26:08,570
>> JASON Hirschhorn: OK.

557
00:26:08,570 --> 00:26:11,690
Nisperaw, dan ma kienx
konfuża lil xi ħadd.

558
00:26:11,690 --> 00:26:15,732
Iżda jekk kien, nistgħu nħarsu lejn din darb'oħra
fil-daqsxejn, għax aħna qed attwalment għaddejjin

559
00:26:15,732 --> 00:26:19,240
għall-kodiċi xi ħaġa li wieħed jittama li
jaħdmu ma 'kordi u jgħinek tħossok

560
00:26:19,240 --> 00:26:22,170
aktar komdi magħhom.

561
00:26:22,170 --> 00:26:24,869
>> Xi kwistjonijiet oħra relatati ma 'dawn
suġġetti jew suġġetti oħra li

562
00:26:24,869 --> 00:26:26,119
I ser jitqiegħdu back up?

563
00:26:26,119 --> 00:26:32,280

564
00:26:32,280 --> 00:26:34,840
U -

565
00:26:34,840 --> 00:26:36,310
dritt issa.

566
00:26:36,310 --> 00:26:37,630
Iva, Alden.

567
00:26:37,630 --> 00:26:39,860
>> ALDEN: Allura dan huwa kompletament mhux relatati,
imma nistgħu biss jmorru fuq

568
00:26:39,860 --> 00:26:42,760
verament malajr dak li għandna bżonn inkunu nafu
dwar id-differenza bejn 32 u

569
00:26:42,760 --> 00:26:46,345
64-bit magna?

570
00:26:46,345 --> 00:26:47,740
>> JASON Hirschhorn: Iva.

571
00:26:47,740 --> 00:26:52,111
Allura 32 bits huwa kemm bytes?

572
00:26:52,111 --> 00:26:53,060
>> ALDEN: Huwa erba 'bytes.

573
00:26:53,060 --> 00:26:54,360
>> JASON Hirschhorn: Huwa erba 'bytes.

574
00:26:54,360 --> 00:26:58,420
U 64 bits huwa kemm bytes?

575
00:26:58,420 --> 00:26:59,112
>> STUDENT: Tmienja.

576
00:26:59,112 --> 00:27:00,610
>> JASON Hirschhorn: Tmien bytes.

577
00:27:00,610 --> 00:27:03,980
Għalhekk għal darb'oħra, tmien bits hija byte wieħed.

578
00:27:03,980 --> 00:27:08,340
CS50 appliance tiegħek
magna 32-bit.

579
00:27:08,340 --> 00:27:13,650
Allura indirizzi memorja huma
erba 'bytes twal.

580
00:27:13,650 --> 00:27:17,460
Hemm 2 għall-32
indirizzi memorja.

581
00:27:17,460 --> 00:27:21,310
0-2 għall-32 minus 1.

582
00:27:21,310 --> 00:27:27,630
And I am not pożittiv, iżda li
probabbilment l-ambitu ta 'dak li għandek bżonn

583
00:27:27,630 --> 00:27:35,230
jaf għal magna 32-bit, li l-memorja
indirizzi huma, għal darb'oħra, erba 'bytes twil,

584
00:27:35,230 --> 00:27:39,620
u dak l-ammont massimu
ta 'indirizzi memorja.

585
00:27:39,620 --> 00:27:41,680
>> Ukoll, tipi ta 'data -

586
00:27:41,680 --> 00:27:45,020
dan jista 'jkun xi ħaġa bħal
ukoll li ta 'min jinnota.

587
00:27:45,020 --> 00:27:49,610
Id-daqs ta 'tip ta' dejta jiddependi fuq
il-magna qed taħdem magħhom.

588
00:27:49,610 --> 00:27:56,760
Allura char, karattru wieħed, huwa kif
ħafna bytes fuq appliance CS50 tagħna?

589
00:27:56,760 --> 00:27:57,980
Waħda byte.

590
00:27:57,980 --> 00:28:02,310
U huwa attwalment byte wieħed bħala
ukoll fuq magna 64-bit.

591
00:28:02,310 --> 00:28:05,920
>> U tipi ta 'data l-aktar huma l-istess numru
ta 'bytes fuq iż-żewġ magni.

592
00:28:05,920 --> 00:28:11,620
Iżda xi tipi ta 'data se jkun differenti
fuq iż-żewġ magni.

593
00:28:11,620 --> 00:28:14,590
Allura li jkunu potenzjalment l-
unika ħaġa li għandek bżonn tkun taf.

594
00:28:14,590 --> 00:28:16,710
>> Iżda anke li, I think,
huwa lil hinn mill-limiti -

595
00:28:16,710 --> 00:28:20,990
Jien kważi pożittiv, jekk inti tħares lura
fi kwizzijiet qodma, huwa jgħid, tassumi għal

596
00:28:20,990 --> 00:28:24,090
kodifikazzjoni problemi li inti qed tuża
magna 32-bit.

597
00:28:24,090 --> 00:28:26,620

598
00:28:26,620 --> 00:28:30,620
Iżda hemm, li jmorru flimkien ma 'dik fil-
każ int interessat, hemm

599
00:28:30,620 --> 00:28:35,920
tipi ta 'data li huma l-istess
daqs fuq il-magni kollha.

600
00:28:35,920 --> 00:28:42,670
>> Jekk inti stajt tidher xi ħaġa bħal
uint32_t, inti tista 'jew tista'

601
00:28:42,670 --> 00:28:43,260
ma raw dan.

602
00:28:43,260 --> 00:28:44,290
Li l-tip ta 'data.

603
00:28:44,290 --> 00:28:47,570
Li huwa qal, ikunu ta '32 bits irrelevanti
liema magna dan huwa fuq.

604
00:28:47,570 --> 00:28:50,350
Allura meta n-nies qed tikteb portabbli
kodiċi, huma probabbilment mhux se jużaw ints.

605
00:28:50,350 --> 00:28:53,260
Huma ser minflok jużaw din id-data l-oħra
tipi li huma jafu se jkun l-istess

606
00:28:53,260 --> 00:28:54,780
daqs fuq kull magna waħda.

607
00:28:54,780 --> 00:28:58,080

608
00:28:58,080 --> 00:28:58,250
Madhu.

609
00:28:58,250 --> 00:29:00,150
>> Madhu: Kelli mistoqsija dwar
il-proċess kumpilazzjoni.

610
00:29:00,150 --> 00:29:04,110
Mela jekk int bil-miktub programm li juża
librerija bħal CS50 jew xi ħaġa

611
00:29:04,110 --> 00:29:06,840
bħal dik, naf li din librerija
għandha, f'xi punt, tkun

612
00:29:06,840 --> 00:29:08,590
miġbura u marbuta pulzieri

613
00:29:08,590 --> 00:29:13,380
Imma kemm ta 'dak li jiġri matul
il-kompilazzjoni tal-programm tiegħek?

614
00:29:13,380 --> 00:29:15,880
Liema parti ta 'dak il-proċess librerija
sseħħ meta int

615
00:29:15,880 --> 00:29:18,560
kumpilazzjoni program tiegħek stess?

616
00:29:18,560 --> 00:29:24,020
>> JASON Hirschhorn: Mela ejja jmorru fuq
ġeneralment l-passi ta 'dan il-proċess.

617
00:29:24,020 --> 00:29:26,280
Tikteb. Fajl tiegħek c.

618
00:29:26,280 --> 00:29:33,530
In. Fajl tiegħek c, inti # Jinkludu tiegħek
libreriji header, per eżempju, cs50.h.

619
00:29:33,530 --> 00:29:39,480
Xi jfisser li jinkludu sharp
line tagħmel biex program tiegħek?

620
00:29:39,480 --> 00:29:40,525
Akchar.

621
00:29:40,525 --> 00:29:43,350
>> AKCHAR: Hija żżid l-prototipi ta '
il-funzjonijiet mill-header

622
00:29:43,350 --> 00:29:45,120
fajls fil-libreriji.

623
00:29:45,120 --> 00:29:45,600
>> JASON Hirschhorn: Eżattament.

624
00:29:45,600 --> 00:29:49,870
Hija żżid dawk prototipi funzjoni
għall-kodiċi tiegħek.

625
00:29:49,870 --> 00:29:55,230
Hekk meta kodiċi tiegħek qed kompilata
l-istadji bikrija, il-kompilatur jaf

626
00:29:55,230 --> 00:29:59,250
li dawn il-funzjonijiet tassew jeżistu, u
li x'imkien ikunu ġew definiti.

627
00:29:59,250 --> 00:30:02,460
Il-fajls. H ma jinkludux il-
definizzjonijiet għal dawn il-funzjonijiet jew kif

628
00:30:02,460 --> 00:30:03,950
huma attwalment jaħdmu.

629
00:30:03,950 --> 00:30:07,960
Cs50.h biss jinkludi xi ħaġa li tgħid
getstring hija ħaġa reali li

630
00:30:07,960 --> 00:30:09,270
jista 'jiġri.

631
00:30:09,270 --> 00:30:14,240
U standardio.h jgħid printf huwa
ħaġa reali li jista 'jiġri.

632
00:30:14,240 --> 00:30:23,190
>> Allura lingwa c tiegħek ma 'dan. Header
file gets mdawwar fis xi

633
00:30:23,190 --> 00:30:27,750
kodiċi tinqara mill-magni, li eventwalment
gets inbidel fi binarju

634
00:30:27,750 --> 00:30:30,030
kodiċi, 0 u 1 ta.

635
00:30:30,030 --> 00:30:33,590
U dak l-kodiċi li finalment
gets esegwiti.

636
00:30:33,590 --> 00:30:38,550
L-l cs50 line - per eżempju,
meta int bil-miktub Clang -

637
00:30:38,550 --> 00:30:41,830
u allura inti jinkludu l cs50,
inti tip li pulzieri

638
00:30:41,830 --> 00:30:42,180
U inti tara li.

639
00:30:42,180 --> 00:30:43,890
Meta tikteb tagħmel, inti ser
tara li linja up here.

640
00:30:43,890 --> 00:30:47,740
U aħna ser tara li fit-tieni meta
aħna kodiċi jew aktar tard meta aħna kodiċi.

641
00:30:47,740 --> 00:30:50,390
>> Iżda dan-l-linja cs50 ma xi ħaġa
daqsxejn differenti minn

642
00:30:50,390 --> 00:30:52,440
il # Jinkludu cs50.h.

643
00:30:52,440 --> 00:30:56,300
X'jagħmel line cs50 li-l jagħmlu?

644
00:30:56,300 --> 00:30:56,820
Avi?

645
00:30:56,820 --> 00:31:00,310
>> AVI: Irrid ngħid li torbot
il-librerija għall-funzjoni

646
00:31:00,310 --> 00:31:02,710
sejħa, bħall-. o files.

647
00:31:02,710 --> 00:31:08,200
>> JASON Hirschhorn: Allura ħafna
qrib, jekk mhux spot-on.

648
00:31:08,200 --> 00:31:16,220
Cs50 l-l jieħu l-fajl binarju u
tgħaqqad ma 'fajl binarju tiegħek.

649
00:31:16,220 --> 00:31:21,410
Allura cs50.h, hemm ebda punt fl-tidwir
cs50.h minn lingwa C sa binarju kull

650
00:31:21,410 --> 00:31:23,130
wieħed ħin huwa qed jintuża.

651
00:31:23,130 --> 00:31:26,650
Dan ikun iblah, minħabba li
jaħlux ħafna ħin.

652
00:31:26,650 --> 00:31:30,420
Allura diġà ġie kkompilat
u mibdula eżekutibbli.

653
00:31:30,420 --> 00:31:35,430
U issa huwa se jingħaqdu
mal-fajl tiegħek fl-aħħar.

654
00:31:35,430 --> 00:31:38,370
Allura dawk tal-1 u 0 huma għaddejjin
biex jingħaqdu ma 'dawk tiegħek

655
00:31:38,370 --> 00:31:39,150
u 0 fi tmiem.

656
00:31:39,150 --> 00:31:43,670
Allura issa inti ser fil-fatt ikollhom l-attwali
1 u 0 li jiddefinixxi kif getstring,

657
00:31:43,670 --> 00:31:47,890
per eżempju, xogħlijiet, jew kif printf,
per eżempju, xogħlijiet.

658
00:31:47,890 --> 00:31:52,750
>> U għal aktar informazzjoni, hemm
kompilaturi qosra li Nate jagħti li

659
00:31:52,750 --> 00:31:55,410
għandek tivverifika li tmur
permezz ta 'dawn il-passi.

660
00:31:55,410 --> 00:31:56,050
Iżda -

661
00:31:56,050 --> 00:31:56,560
iva.

662
00:31:56,560 --> 00:32:01,700
>> STUDENT: Huma dejjem fil-o files.
meta jkunu qed fil-forma librerija,

663
00:32:01,700 --> 00:32:06,764
lesti biex jiġu amalgamati, marbuta - bħal
dawn qed fil-kodiċi binarju?

664
00:32:06,764 --> 00:32:07,600
>> JASON Hirschhorn: OK.

665
00:32:07,600 --> 00:32:08,420
What -

666
00:32:08,420 --> 00:32:11,780
>> STUDENT: Huwa li dejjem il-każ għall-
il-libreriji meta inti jorbtuhom?

667
00:32:11,780 --> 00:32:12,500
>> JASON Hirschhorn: Iva.

668
00:32:12,500 --> 00:32:17,300
Allura hemm files, li ser ikunu s. S
kodiċi tal-magna, li se jkun ukoll

669
00:32:17,300 --> 00:32:17,975
cryptic lilek.

670
00:32:17,975 --> 00:32:19,410
Inti ma għandekx bżonn ninkwetaw dwar dawk.

671
00:32:19,410 --> 00:32:24,930
Iżda ġeneralment, yeah, dawn ser
jkun. o fajls lesta li tmur.

672
00:32:24,930 --> 00:32:27,170
>> STUDENT: Allura meta inti vapur li
librerija, inti biss vapur

673
00:32:27,170 --> 00:32:28,880
l. h u l-. o?

674
00:32:28,880 --> 00:32:32,210
Inti ma vapur li l-. C jew l. S.

675
00:32:32,210 --> 00:32:33,070
>> JASON Hirschhorn: So -

676
00:32:33,070 --> 00:32:36,260
u dan huwa f'dan qasir kif ukoll, jekk
din l-informazzjoni tidher li ġejja

677
00:32:36,260 --> 00:32:36,700
ftit malajr.

678
00:32:36,700 --> 00:32:39,870
Iżda l-qasir fuq kompilaturi
taħdidiet dwar dan ukoll.

679
00:32:39,870 --> 00:32:43,290
Meta inti vapur librerija, jekk inti vapur
l. h, il-fajl tal-header, dawk

680
00:32:43,290 --> 00:32:46,290
prototipi funzjoni, u l-l-1 u
0, dak kollu li għandek bżonn biex tagħti.

681
00:32:46,290 --> 00:32:50,640
Inti ma għandekx bżonn li jagħtu kif il-
funzjoni xogħlijiet, il-fajl c..

682
00:32:50,640 --> 00:32:56,360
Minħabba li l-punt ta 'estrazzjoni, jew il-
punt APIs, il-punt li dan SPL,

683
00:32:56,360 --> 00:32:59,650
il-librerija portabbli Stanford, huwa
għalik biex ma joqogħdu jinkwetaw dwar kif il-ġdid

684
00:32:59,650 --> 00:33:04,220
GRect xogħlijiet, jew kif jimxu xogħlijiet,
jew kif żid xogħlijiet.

685
00:33:04,220 --> 00:33:06,520
Kulma għandek bżonn tkun taf hija li add
hija funzjoni li tista '

686
00:33:06,520 --> 00:33:08,880
użu, u dan tagħmlu.

687
00:33:08,880 --> 00:33:12,760
Allura int verament ma bżonn ikunu jafu kif
Huwa bil-miktub fil C. Inti biss ħtieġa li

688
00:33:12,760 --> 00:33:15,460
taf, hawn huma l-funzjonijiet, dak li
tagħmel, u hawn huma l-tal-1 u 0

689
00:33:15,460 --> 00:33:18,870
meta int verament tixtieq li jużawhom.

690
00:33:18,870 --> 00:33:19,530
>> Kessaħ.

691
00:33:19,530 --> 00:33:26,980
Kwalunkwe mistoqsijiet aktar fuq kompilaturi
jew suġġetti oħra fuq il-bord?

692
00:33:26,980 --> 00:33:30,300
>> STUDENT: Għandi mistoqsija ta '
implimentazzjoni funzjonijiet jirrikorri.

693
00:33:30,300 --> 00:33:31,170
A mistoqsija dwar recursion.

694
00:33:31,170 --> 00:33:33,030
I kellhom tħossok li se toħroġ.

695
00:33:33,030 --> 00:33:38,310
Mela ejja malajr jgħaddu
recursion bi speċifiku

696
00:33:38,310 --> 00:33:40,690
eż., funzjoni fattorjali.

697
00:33:40,690 --> 00:33:44,920
Minħabba li dan huwa eżempju li
sikwit jiġi up u huwa użat

698
00:33:44,920 --> 00:33:46,170
biex juru recursion.

699
00:33:46,170 --> 00:33:52,390

700
00:33:52,390 --> 00:33:56,410
>> Allura "4!" tinqara bħala 4 fattorjali.

701
00:33:56,410 --> 00:33:59,120
U dak ma 4 fattorjali jfisser?

702
00:33:59,120 --> 00:34:00,696
Dak li ma tagħmel?

703
00:34:00,696 --> 00:34:02,235
Kif inti tikkalkula 4 fattorjali?

704
00:34:02,235 --> 00:34:05,250

705
00:34:05,250 --> 00:34:07,960
4 darbiet 3 darbiet 2 darbiet 1.

706
00:34:07,960 --> 00:34:11,889
>> Allura mod ieħor biex jiktbu 4 fattorjali
huwa li tikteb din.

707
00:34:11,889 --> 00:34:16,780

708
00:34:16,780 --> 00:34:19,022
4 darbiet 3 fattorjali.

709
00:34:19,022 --> 00:34:22,080
Minħabba 3 fatturi hija
3 darbiet 2 darbiet 1.

710
00:34:22,080 --> 00:34:27,580
Allura 4 darbiet 3 fattorjali huwa 4
drabi 3 darbiet 2 darbiet 1.

711
00:34:27,580 --> 00:34:32,679
Dan huwa għaliex fattoriku huwa kbir
kandidat għall recursion, għaliex dan huwa

712
00:34:32,679 --> 00:34:36,630
ċar li hemm xi ħaġa li
jiġri aktar u aktar u aktar fuq

713
00:34:36,630 --> 00:34:39,820
numru iżgħar ta 'affarijiet sakemm
inti jilħqu t-tmiem.

714
00:34:39,820 --> 00:34:42,570
Meta inti tilħaq 1, 1 fattoriku huwa 1.

715
00:34:42,570 --> 00:34:43,719
Inti ma tistax tmur ħafna aktar.

716
00:34:43,719 --> 00:34:47,219
0 fatturi huwa wkoll definit bħala 1.

717
00:34:47,219 --> 00:34:50,679
Allura meta ikollok 1 jew 0, int
fl-aħħar, u inti tista '

718
00:34:50,679 --> 00:34:53,219
tibda tmur lura up.

719
00:34:53,219 --> 00:34:59,540
Hekk jekk ridna li jiktbu rikursivi
funzjoni biex tikkalkola fatturi,

720
00:34:59,540 --> 00:35:02,170
aħna qed tmur biex jiktbu xi
pseudocode għal dak issa.

721
00:35:02,170 --> 00:35:03,300
Qabel aħna tikteb li pseudocode -

722
00:35:03,300 --> 00:35:05,660
I ser jagħtuk guys ftit minuti
biex jikteb il-kodiċi psewdo jew biss jaħsbu

723
00:35:05,660 --> 00:35:09,600
dwar dan - hemm żewġ affarijiet kull
funzjoni jirrikorri bżonnijiet.

724
00:35:09,600 --> 00:35:12,530
Liema huma dawn iż-żewġ affarijiet?

725
00:35:12,530 --> 00:35:13,220
>> JACK: Għandu sejħa nnifisha.

726
00:35:13,220 --> 00:35:13,680
>> JASON Hirschhorn: Noah?

727
00:35:13,680 --> 00:35:14,460
Oh, Jack.

728
00:35:14,460 --> 00:35:15,100
Jimxi 'l quddiem.

729
00:35:15,100 --> 00:35:16,640
>> JACK: Għandu sejħa nnifisha.

730
00:35:16,640 --> 00:35:19,220
>> JASON Hirschhorn: Allura rikursivi
funzjoni teħtieġ sejħa jirrikorri, a

731
00:35:19,220 --> 00:35:20,220
sejħa biex innifsu.

732
00:35:20,220 --> 00:35:20,770
Din kienet waħda.

733
00:35:20,770 --> 00:35:21,510
U x'inhu l-ħaġa oħra?

734
00:35:21,510 --> 00:35:22,250
>> JACK: A każ bażi.

735
00:35:22,250 --> 00:35:23,780
>> JASON Hirschhorn: A każ bażi.

736
00:35:23,780 --> 00:35:26,940
A każ bażi huwa, hawn meta aħna stop.

737
00:35:26,940 --> 00:35:29,510
Allura funzjoni tiegħek gets imsejħa.

738
00:35:29,510 --> 00:35:31,410
Il-każ bażiku jiġi l-ewwel.

739
00:35:31,410 --> 00:35:33,710
Inti trid tkun taf jekk int fl-aħħar.

740
00:35:33,710 --> 00:35:37,110
U jekk int ma fl-aħħar, inti
jagħmlu sejħa jirrikorri tiegħek.

741
00:35:37,110 --> 00:35:39,880
U inti tmur permezz din il-funzjoni mill-ġdid,
iċċekkja każ bażi tiegħek mill-ġdid.

742
00:35:39,880 --> 00:35:42,575
Jekk int mhux l-aħħar, inti tagħmel
sejħa oħra rikursivi,

743
00:35:42,575 --> 00:35:44,130
eċċetera, eċċetera.

744
00:35:44,130 --> 00:35:47,110
>> C'est pourquoi funzjonijiet jirrikorri dejjem
bżonn dawk il-każijiet bażi u dawk

745
00:35:47,110 --> 00:35:48,210
sejħiet rikursivi.

746
00:35:48,210 --> 00:35:51,280
Jekk inti ma għandekx sejħa rikursivi, huwa
ma tkunx funzjoni jirrikorri.

747
00:35:51,280 --> 00:35:53,210
Jekk inti ma jkollhom każ bażi,
inti tmur dejjem u

748
00:35:53,210 --> 00:35:54,780
ma jkun hemm l-ebda tmiem.

749
00:35:54,780 --> 00:35:57,870
U l-każ bażi dejjem jiġi l-ewwel,
għaliex inti dejjem se tkun trid tivverifika

750
00:35:57,870 --> 00:36:00,420
jekk int fl-aħħar ewwel.

751
00:36:00,420 --> 00:36:04,770
Għalhekk qabel ma nagħmlu xi pseudocode, għaliex
ma inti tieħu minuta biex jaħsbu dwar

752
00:36:04,770 --> 00:36:09,360
kif funzjoni fattorjali jirrikorri
tkun miktuba?

753
00:36:09,360 --> 00:36:23,340

754
00:36:23,340 --> 00:36:26,010
>> Ukoll, kemm inti qiegħed tagħmel, bil-miktub
it out fuq folja tal-karta hija

755
00:36:26,010 --> 00:36:27,960
dak li int se jkollhom
tagħmel fuq l-kwizz għada.

756
00:36:27,960 --> 00:36:32,160
Prattika hekk probabbilment tajba biex jagħmlu
żgur il-kodiċi int bil-miktub

757
00:36:32,160 --> 00:36:34,420
isfel fuq folja tal-karta -

758
00:36:34,420 --> 00:36:35,160
jew inti tista 'tagħmel dan.

759
00:36:35,160 --> 00:36:36,710
Inti taf fejn il-semicolons huma.

760
00:36:36,710 --> 00:36:37,660
Tiftakar l-sintassi.

761
00:36:37,660 --> 00:36:40,400
Minħabba li int ma tkun kapaċi li jkollhom
kompilatur jgħidlek għamel żball.

762
00:36:40,400 --> 00:37:02,356

763
00:37:02,356 --> 00:37:07,240
>> Ukoll, f'dan is-sens, għada, meta
għandek kodifikazzjoni problemi, jekk inti

764
00:37:07,240 --> 00:37:11,490
huma ġrew għal żmien, jew jekk int ħafna
konfuż dwar kif int suppost

765
00:37:11,490 --> 00:37:16,030
tikteb il-ħaġa partikolari c, huwa
kieku behoove inti tikteb psewdo-kodiċi

766
00:37:16,030 --> 00:37:18,160
jew ikteb kummenti fil ukoll.

767
00:37:18,160 --> 00:37:21,940
Għaliex hemm kreditu parzjali għal
Ħafna mill-mistoqsijiet dwar l-kwizz.

768
00:37:21,940 --> 00:37:24,840
Allura inti jista 'jkun ġrew, jew inti
jistgħu biss jiġu konfużi.

769
00:37:24,840 --> 00:37:28,030
Miktub kummenti jew psewdo-kodiċi
spiss huma modi li inti

770
00:37:28,030 --> 00:37:29,360
jistgħu jiksbu kreditu parzjali.

771
00:37:29,360 --> 00:37:31,440
>> Allura ma jħallux xi ħaġa
vojta fuq il-kwizz.

772
00:37:31,440 --> 00:37:33,490
M'hemm l-ebda penali għall-
tqegħid affarijiet pulzieri

773
00:37:33,490 --> 00:37:37,650
Fil-fatt, it-tqegħid fis-psewdo-kodiċi jew
kummenti se tgħin lill-grader

774
00:37:37,650 --> 00:37:40,410
insemmu jekk inti fil-fatt jafu liema
qed jitkellem dwar, u forsi għoti

775
00:37:40,410 --> 00:37:42,030
inti xi kreditu parzjali għal dak.

776
00:37:42,030 --> 00:37:44,510
>> Wkoll f'dan is-sens, ikteb ċar.

777
00:37:44,510 --> 00:37:47,650
Jekk ma nistgħux verament dak li qed tikteb,
aħna qed mhux se sejħa inti

778
00:37:47,650 --> 00:37:49,900
fil għada nofsillejl figura
barra dak li kiteb.

779
00:37:49,900 --> 00:37:51,520
Aħna biss ser jieħdu off punti.

780
00:37:51,520 --> 00:37:56,570
Ikteb b'mod ċar hekk nistgħu jisma ', jew minflok,
nistgħu taqra dak li kiteb.

781
00:37:56,570 --> 00:38:00,230
>> U jekk din tgħid żewġ sentenzi,
ma jiktbu paragrafu.

782
00:38:00,230 --> 00:38:02,280
Segwi l-istruzzjonijiet.

783
00:38:02,280 --> 00:38:03,500
Ikteb b'mod ċar.

784
00:38:03,500 --> 00:38:07,720
U jiktbu dawk il-kummenti jew
pseudocode għal mistoqsijiet li jista '

785
00:38:07,720 --> 00:38:10,270
għoti ta 'kreditu parzjali.

786
00:38:10,270 --> 00:38:12,520
>> OK, ejja mur fattorjali.

787
00:38:12,520 --> 00:38:15,000
Allura aħna għandna fattorjali funzjoni.

788
00:38:15,000 --> 00:38:18,400

789
00:38:18,400 --> 00:38:21,550
Jekk I kienu biex effettivament tikteb dan fis-C,
dak li għandi bżonn li tressaq quddiem l-isem

790
00:38:21,550 --> 00:38:22,800
tal-funzjoni?

791
00:38:22,800 --> 00:38:24,880

792
00:38:24,880 --> 00:38:30,060
It-tip ta 'ritorn, li, f'dan il-
każ, aħna ser tagħtiha int.

793
00:38:30,060 --> 00:38:35,450
U mbagħad ġewwa l-braces kaboċċi, huwa
dak li tmur ġewwa l-braces kaboċċi għall

794
00:38:35,450 --> 00:38:36,850
funzjoni?

795
00:38:36,850 --> 00:38:37,950
>> STUDENTI: tip Argument.

796
00:38:37,950 --> 00:38:39,150
>> JASON Hirschhorn: L-argumenti tagħha.

797
00:38:39,150 --> 00:38:42,680
Allura fatturi probabbilment se
jieħdu argument.

798
00:38:42,680 --> 00:38:44,500
Hija ser probabbilment jieħu biss argument wieħed.

799
00:38:44,500 --> 00:38:49,450
U aħna ser ngħidu li ser tieħu
integer imsejħa x.

800
00:38:49,450 --> 00:38:52,770
U għal darb'oħra, meta tikteb il-prototip ta '
funzjoni jew bil-miktub il-funzjoni

801
00:38:52,770 --> 00:38:57,110
fil-kodiċi tiegħek qabel ma jiddefinixxu dan, inti
jikteb dejta tat-tip u l-isem ta '

802
00:38:57,110 --> 00:39:01,370
dak il-varjabbli għal dik il-funzjoni biss.

803
00:39:01,370 --> 00:39:06,350
Allura inti tista 'tgħaddi xi numru fis dan
funzjoni, li ser jissejjaħ x

804
00:39:06,350 --> 00:39:07,340
internament.

805
00:39:07,340 --> 00:39:08,755
>> Għandna funzjoni fattorjali tagħna.

806
00:39:08,755 --> 00:39:12,030

807
00:39:12,030 --> 00:39:15,850
Għandna bżonn żewġ affarijiet, każ bażiku
u sejħa jirrikorri.

808
00:39:15,850 --> 00:39:20,900
X'inhu l-każ ta 'bażi ​​għall-fatturi?

809
00:39:20,900 --> 00:39:24,850
Xi ħadd li kiteb dan jitwettaq u li ma jkunx
mitkellma għadhom, dak li huwa l-bażi

810
00:39:24,850 --> 00:39:26,100
każ għall-fatturi?

811
00:39:26,100 --> 00:39:28,400

812
00:39:28,400 --> 00:39:30,930
>> STUDENT: Jekk n hija anqas
minn 2, ritorn 1.

813
00:39:30,930 --> 00:39:33,520
>> JASON Hirschhorn: Jekk n hija
inqas minn 2, ritorn 1.

814
00:39:33,520 --> 00:39:37,216
I simili li, minħabba li
jieħu ħsieb ta '0 u 1.

815
00:39:37,216 --> 00:39:45,290
Allura aħna ser nagħmlu x <2, ritorn 1.

816
00:39:45,290 --> 00:39:47,870
Jekk irridu jiksbu għadda 0, jekk irridu jiksbu
għadda 1, din il-funzjoni se

817
00:39:47,870 --> 00:39:49,790
immedjatament ritorn 1.

818
00:39:49,790 --> 00:39:54,020
Jekk aħna jiksbu għadda xi numru akbar
minn jew daqs 2, aħna qed tmur biex

819
00:39:54,020 --> 00:39:55,370
jkollhom sejħa jirrikorri tagħna.

820
00:39:55,370 --> 00:39:57,855
>> U hekk kif huwa li sejjer jaħdem?

821
00:39:57,855 --> 00:40:01,070
Jista xi ħadd ieħor li ħadem fuq din
li ma tkunx mitkellma għadha agħtini l-

822
00:40:01,070 --> 00:40:07,380
sejħa jirrikorri għal din il-funzjoni
fil pseudocode?

823
00:40:07,380 --> 00:40:10,770
Jekk aħna jiksbu għadda fl-għadd ta 'x
u huwa ikbar minn 2, liema

824
00:40:10,770 --> 00:40:13,370
do rridu nagħmlu?

825
00:40:13,370 --> 00:40:17,930
Għandna wkoll eżempju bil-miktub dwar il-
ġenb li jistgħu jagħtuk ħjiel.

826
00:40:17,930 --> 00:40:20,770
>> STUDENT: Sejħa x darbiet il-
fattorjali ta x minus 1?

827
00:40:20,770 --> 00:40:22,020
>> JASON Hirschhorn: Eżattament dritt.

828
00:40:22,020 --> 00:40:24,610

829
00:40:24,610 --> 00:40:37,750
Aħna ser jirritorna x drabi
l fattorjali ta x minus 1.

830
00:40:37,750 --> 00:40:41,810
U li, anki jekk I kiteb up,
bażikament, dak li qal fl-Ingliż,

831
00:40:41,810 --> 00:40:44,580
din il-funzjoni fatturi
se tikseb imsejħa mill-ġdid.

832
00:40:44,580 --> 00:40:46,320
Hija ser teżegwixxi fuq x minus 1.

833
00:40:46,320 --> 00:40:49,320
Hija ser jirritorna ma 'xi numru sħiħ, u
allura dan ser timmultiplika dawn iż-żewġ

834
00:40:49,320 --> 00:40:52,050
flimkien, u li l-valur se jkun
lura għal dak kollu li sejjaħ din

835
00:40:52,050 --> 00:40:55,010
, funzjoni fatturi li jistgħu
jkun eżempju ieħor ta '

836
00:40:55,010 --> 00:40:58,420
din il-funzjoni fattorjali.

837
00:40:58,420 --> 00:41:01,360
>> Allura dan huwa eżempju ta 'rikursivi
funzjoni, ħafna

838
00:41:01,360 --> 00:41:02,530
funzjoni jirrikorri sempliċi.

839
00:41:02,530 --> 00:41:04,530
Iżda ħafna minnhom se jkun bħal dan.

840
00:41:04,530 --> 00:41:11,170
Jekk inti tixtieq a rikursivi tajba
isfida għall-kwizz, ipprova kodifikazzjoni

841
00:41:11,170 --> 00:41:13,230
tfittxija binarja recursively.

842
00:41:13,230 --> 00:41:18,950
Għaliex jekk inti ma tfittxija binarju għal
problema sett tlieta, inti probabilment ma kien

843
00:41:18,950 --> 00:41:21,730
iteratively fil-linja waqt.

844
00:41:21,730 --> 00:41:23,700
>> Iżda tista 'wkoll tkun bil-miktub
recursively.

845
00:41:23,700 --> 00:41:26,310
Int ser bżonn jiktbu tiegħek
funzjoni separata li jieħu xi

846
00:41:26,310 --> 00:41:29,020
argumenti differenti kmand tal-linja - jew
mhux argumenti kmand tal-linja, li wħud

847
00:41:29,020 --> 00:41:30,910
argumenti biss regolari differenti.

848
00:41:30,910 --> 00:41:33,870
Iżda int tista 'tikteb tfittxija binarja
recursively ukoll.

849
00:41:33,870 --> 00:41:36,190
>> STUDENT: Allura inti tista 'ukoll bil-miktub,
minflok x minus 1, inti

850
00:41:36,190 --> 00:41:39,502
seta 'wkoll miktuba x minus
minus, jew inti jista 'jkollhom

851
00:41:39,502 --> 00:41:40,830
miktub minus minus x.

852
00:41:40,830 --> 00:41:44,740
Tista 'biss tispjega verament malajr għaliex
dawk tkun l-affarijiet differenti,

853
00:41:44,740 --> 00:41:49,510
bħall x'inhi d-differenza bejn
x minus minus u minus minus x?

854
00:41:49,510 --> 00:41:51,320
>> JASON Hirschhorn: Le, jien ma
se jmorru f'dak.

855
00:41:51,320 --> 00:41:55,500
Imma jien ser jitkellem miegħek dwar dan wara
klassi. x minus minus, minus minus x

856
00:41:55,500 --> 00:41:57,780
decrement x minn 1.

857
00:41:57,780 --> 00:41:59,090
Iżda dawn ma hija daqsxejn differenti.

858
00:41:59,090 --> 00:42:00,340
Imma jien ma jridu jmorru f'dak.

859
00:42:00,340 --> 00:42:04,330

860
00:42:04,330 --> 00:42:09,090
Mistoqsijiet oħra dwar recursion
jew din il-funzjoni?

861
00:42:09,090 --> 00:42:10,140
Li mhux verament anki pseudocode.

862
00:42:10,140 --> 00:42:15,060
Dik hija bażikament l-kodiċi fil-
C inti se jikteb għal dan.

863
00:42:15,060 --> 00:42:19,393
>> OK, kwalunkwe mistoqsijiet oħra
dwar suġġetti up hawn?

864
00:42:19,393 --> 00:42:19,864
Yeah.

865
00:42:19,864 --> 00:42:23,130
>> STUDENT: I ​​jkollhom telqa malajr ta '
floating point u preċiżjoni.

866
00:42:23,130 --> 00:42:24,260
>> JASON Hirschhorn: Floating
punt u preċiżjoni.

867
00:42:24,260 --> 00:42:26,920
Jista xi ħadd verament malajr
tagħti me telqa ta '

868
00:42:26,920 --> 00:42:28,210
floating point u preċiżjoni?

869
00:42:28,210 --> 00:42:30,420
Inti kollha kellhom jagħmlu dan għall tiegħek
problema stabbiliti, hekk int kollha

870
00:42:30,420 --> 00:42:31,700
familjari magħha.

871
00:42:31,700 --> 00:42:35,090
Jew forsi mhux kollha inti.

872
00:42:35,090 --> 00:42:36,602
Kulħadd?

873
00:42:36,602 --> 00:42:39,530
Agħti me post beda.

874
00:42:39,530 --> 00:42:40,750
Floating punt u preċiżjoni.

875
00:42:40,750 --> 00:42:42,380
X'hemm l-problema?

876
00:42:42,380 --> 00:42:42,960
Iva.

877
00:42:42,960 --> 00:42:43,680
Victoria?

878
00:42:43,680 --> 00:42:44,480
>> Vanessa: Vanessa.

879
00:42:44,480 --> 00:42:45,285
>> JASON Hirschhorn: Vanessa.

880
00:42:45,285 --> 00:42:45,680
Jiddispjacini.

881
00:42:45,680 --> 00:42:51,550
>> Vanessa: Hemm biss numru finit
ta 'numri li jistgħu jkunu rrappreżentati

882
00:42:51,550 --> 00:42:57,930
għaliex int fuq, fil tagħna
każ, sistema 32-bit.

883
00:42:57,930 --> 00:43:03,080
Allura inti tip ta 'għandek
jagħmlu up xi numri.

884
00:43:03,080 --> 00:43:03,910
>> JASON Hirschhorn: Allura dak
eżattament id-dritt.

885
00:43:03,910 --> 00:43:08,110
Hemm biss ċertu ammont ta '
numri li jistgħu jkunu rrappreżentati.

886
00:43:08,110 --> 00:43:11,770
Jekk inti immoltiplika żewġ numri kbar ħafna,
jista jfur l-ammont

887
00:43:11,770 --> 00:43:13,950
ta 'spazji għandek biex jirrappreżentaw
integer.

888
00:43:13,950 --> 00:43:17,930
C'est pourquoi kultant nużaw
twil twil minflok int.

889
00:43:17,930 --> 00:43:19,210
Li għandha aktar spazji.

890
00:43:19,210 --> 00:43:21,210
Li tista 'żżomm numru akbar.

891
00:43:21,210 --> 00:43:24,310
>> Floating point preċiżjoni għandha x'taqsam ma '
li, iżda għandha wkoll tagħmel il-

892
00:43:24,310 --> 00:43:29,300
fatt li n-numri deċimali jkunu
mhux dejjem irrappreżentata.

893
00:43:29,300 --> 00:43:29,540
Jiddispjacini.

894
00:43:29,540 --> 00:43:31,280
Let me tpoġġi dan back up.

895
00:43:31,280 --> 00:43:36,610
In-numru ta 'informazzjoni 1.0 mhuwiex dejjem
irrappreżentata bħal inti tistenna,

896
00:43:36,610 --> 00:43:40,770
1.000000000.

897
00:43:40,770 --> 00:43:50,360
Huwa xi kultant rappreżentati kif
1.000000001 jew 0.999999999.

898
00:43:50,360 --> 00:43:52,780
Jista 'jkun saħansitra 89 jintefgħu
fil hemm x'imkien.

899
00:43:52,780 --> 00:43:56,560
Allura dawn in-numri deċimali mhumiex
irrappreżentata eżattament bħall inti

900
00:43:56,560 --> 00:43:58,430
tistenna li tkun rappreżentata.

901
00:43:58,430 --> 00:44:00,010
>> Allura fil-problema stabbilita -

902
00:44:00,010 --> 00:44:00,860
kien it tnejn? -

903
00:44:00,860 --> 00:44:05,290
problema stabbiliti tnejn, fejn aħna ttrattati
b'punt li jvarja numri, meta ridna

904
00:44:05,290 --> 00:44:08,690
minnhom jirrappreżentaw eżattament dak li ridna
minnhom jirrappreżentaw, in-numru

905
00:44:08,690 --> 00:44:12,860
ta 'pennies, jew in-numru ta' ċenteżmi,
aħna timmultiplika dawn bil 100.

906
00:44:12,860 --> 00:44:14,750
We tond lilhom.

907
00:44:14,750 --> 00:44:18,660
U allura aħna maqtugħa kollox
wara l-punt deċimali.

908
00:44:18,660 --> 00:44:22,020
Li kien li jiġi żgurat li dawn
attwalment ugwali eżattament dak li ridna

909
00:44:22,020 --> 00:44:22,410
lill ugwali.

910
00:44:22,410 --> 00:44:26,870
>> Għaliex meta inti tieħu xi ħaġa li
a float u jibdluh int, int

911
00:44:26,870 --> 00:44:29,860
cut off kollox lejn il-lemin
tal-punt deċimali.

912
00:44:29,860 --> 00:44:33,900
Minħabba li hemm xi b'punt li jvarja
impreċiżjoni, 100.000 jista 'jkun

913
00:44:33,900 --> 00:44:37,440
rappreżentati kif 99.999999999.

914
00:44:37,440 --> 00:44:40,350
U jekk inti biss cut off kollox biex
id-dritt dritt bogħod, int ser

915
00:44:40,350 --> 00:44:41,600
jiksbu n-numru żbaljat.

916
00:44:41,600 --> 00:44:44,050

917
00:44:44,050 --> 00:44:44,180
Yeah.

918
00:44:44,180 --> 00:44:45,290
>> STUDENT: Kelli mistoqsija
dwar ikkastjar.

919
00:44:45,290 --> 00:44:47,500
F'liema ordni ma jseħħu?

920
00:44:47,500 --> 00:44:54,480
Jekk tixtieq tagħmel float, brazzi, 1 maqsuma
b'10, ma tagħmel 1 maqsum f'10,

921
00:44:54,480 --> 00:44:58,910
imbagħad nikseb 0.1, imbagħad ixgħel
hija fis-float?

922
00:44:58,910 --> 00:45:01,470
>> JASON Hirschhorn: Jekk inti tagħmel
float 1 maqsum f'10 -

923
00:45:01,470 --> 00:45:02,550
>> STUDENT: Yeah, u mbagħad ugwali -

924
00:45:02,550 --> 00:45:04,240
ukoll, huwa normalment
għandna hija ugwali fil -

925
00:45:04,240 --> 00:45:04,690
Yeah.

926
00:45:04,690 --> 00:45:06,760
Inti tixtieq li tagħmel dan float, right?

927
00:45:06,760 --> 00:45:12,790
>> JASON Hirschhorn: OK, hekk aħna qed tmur biex
użu li segue fis jidhru

928
00:45:12,790 --> 00:45:15,390
it-tweġibiet għal dawn il-mistoqsijiet
permezz kodifikazzjoni.

929
00:45:15,390 --> 00:45:18,180
Għaliex inti probabilment jkollhom ħafna ta '
dawn il-mistoqsijiet minuta, u mod tajjeb

930
00:45:18,180 --> 00:45:19,100
biex isolvuhom huwa permezz kodifikazzjoni.

931
00:45:19,100 --> 00:45:21,320
Allura aħna qed tmur għall-kodiċi dan id-dritt issa,
u allura aħna qed tmur biex tmur lura u

932
00:45:21,320 --> 00:45:24,020
kodiċi l-kwistjoni kellek.

933
00:45:24,020 --> 00:45:24,950
>> Allura l-ewwel linja -

934
00:45:24,950 --> 00:45:29,390
I m'għandhomx ktibt dan - dak li huwa
l-ewwel ħaġa li rridu nagħmlu meta aħna

935
00:45:29,390 --> 00:45:32,250
tiftaħ fajl ġdid fl gedit?

936
00:45:32,250 --> 00:45:34,190
>> STUDENT: Inkludi.

937
00:45:34,190 --> 00:45:35,920
>> JASON Hirschhorn: Inkludi liema?

938
00:45:35,920 --> 00:45:37,952
>> STUDENT: librerija CS50.

939
00:45:37,952 --> 00:45:39,920
>> JASON Hirschhorn: OK.

940
00:45:39,920 --> 00:45:42,590
X'iktar għandna jinkludu?

941
00:45:42,590 --> 00:45:46,820
Aħna biss ser jiċċekkja dak li jiġri
meta inti mitfugħa xi ħaġa li float.

942
00:45:46,820 --> 00:45:48,605
Imma dak li għandna bżonn li jinkludu jekk aħna qed
ser jikteb programm C?

943
00:45:48,605 --> 00:45:49,300
>> STUDENT: Standard I / O.

944
00:45:49,300 --> 00:45:50,625
>> JASON Hirschhorn: stdio.h.

945
00:45:50,625 --> 00:45:54,880
Aħna attwalment m'għandhomx bżonn, għal dan
programm, cs50.h, anki jekk huwa

946
00:45:54,880 --> 00:45:55,920
dejjem utli li jinkludiha.

947
00:45:55,920 --> 00:45:58,260
Iżda aħna dejjem bżonn stdio.h.

948
00:45:58,260 --> 00:45:59,660
>> STUDENT: Meta kodifikazzjoni C?

949
00:45:59,660 --> 00:46:15,770
>> JASON Hirschhorn: Meta kodifikazzjoni C.

950
00:46:15,770 --> 00:46:17,090
>> So I ħlief bħala dan. Fajl c.

951
00:46:17,090 --> 00:46:18,590
I nikseb xi sintassi enfasizzat sbieħ.

952
00:46:18,590 --> 00:46:22,890
I kiteb null ġewwa prinċipali.

953
00:46:22,890 --> 00:46:24,792
X'tagħmel null jfisser?

954
00:46:24,792 --> 00:46:26,740
>> STUDENT: Ma tieħu kwalunkwe
argumenti kmand tal-linja.

955
00:46:26,740 --> 00:46:28,900
>> JASON Hirschhorn: mezzi Null, f'dan il-
każ, prinċipali ma tieħu kwalunkwe

956
00:46:28,900 --> 00:46:29,700
argumenti kmand tal-linja.

957
00:46:29,700 --> 00:46:32,720
F'każijiet oħra, dan ifisser il-funzjoni
ma tieħu argumenti kmand tal-linja.

958
00:46:32,720 --> 00:46:36,560
Jew il-funzjoni, jekk I kellhom jiktbu nulli
prinċipali (vojt), li jgħidu li ewlenin

959
00:46:36,560 --> 00:46:38,460
ma jirritornaw xejn.

960
00:46:38,460 --> 00:46:39,960
Allura vojt ifisser biss xejn.

961
00:46:39,960 --> 00:46:42,510
X'għandu I jiktbu jekk I kellhom
tieħu argumenti kmand tal-linja?

962
00:46:42,510 --> 00:46:45,250

963
00:46:45,250 --> 00:46:47,150
>> STUDENT: int ark c ark string v

964
00:46:47,150 --> 00:46:49,055
>> JASON Hirschhorn: int
argc ARGV string.

965
00:46:49,055 --> 00:46:54,050

966
00:46:54,050 --> 00:46:55,572
Huwa dan id-dritt?

967
00:46:55,572 --> 00:46:58,720
>> STUDENT: Huwa parentesi ARGV star char.

968
00:46:58,720 --> 00:47:01,730
>> JASON Hirschhorn: Allura inti tista 'tikteb
parentesi ARGV string jew ARGV star char

969
00:47:01,730 --> 00:47:03,710
parentesi, iżda inti għandek bżonn l-parentesi.

970
00:47:03,710 --> 00:47:06,290
Minħabba ARGV huwa array
ta 'spag, ftakar.

971
00:47:06,290 --> 00:47:07,360
Huwa mhux biss wieħed string.

972
00:47:07,360 --> 00:47:10,350
Allura ARGV string hija, hawn
string wieħed imsejjaħ ARGV.

973
00:47:10,350 --> 00:47:13,630
Parentesi ARGV String hija, hawn
firxa ta 'kordi.

974
00:47:13,630 --> 00:47:17,865
Parentesi ARGV string argc hekk int
tkun xi ħaġa li jien

975
00:47:17,865 --> 00:47:18,810
probabbilment jiktbu.

976
00:47:18,810 --> 00:47:23,050
>> Allura inti riedu ħlief integer?

977
00:47:23,050 --> 00:47:24,285
>> STUDENT: Yeah, numru sħiħ.

978
00:47:24,285 --> 00:47:25,840
Jew float.

979
00:47:25,840 --> 00:47:26,710
>> JASON Hirschhorn: Fi float?

980
00:47:26,710 --> 00:47:30,790
Bħal, float x daqs 1 maqsum f'10.

981
00:47:30,790 --> 00:47:32,040
>> JASON Hirschhorn: OK.

982
00:47:32,040 --> 00:47:40,160

983
00:47:40,160 --> 00:47:42,240
Kif nista jistampa float fl printf?

984
00:47:42,240 --> 00:47:45,100

985
00:47:45,100 --> 00:47:46,714
What?

986
00:47:46,714 --> 00:47:47,560
>> STUDENT:% f.

987
00:47:47,560 --> 00:47:48,300
>> JASON Hirschhorn:% f.

988
00:47:48,300 --> 00:47:50,810
X'hemm integer?

989
00:47:50,810 --> 00:47:52,110
d jew i.

990
00:47:52,110 --> 00:47:53,000
X'hemm a string?

991
00:47:53,000 --> 00:47:54,240
>> STUDENT: s.

992
00:47:54,240 --> 00:47:56,140
>> JASON Hirschhorn: s.

993
00:47:56,140 --> 00:47:57,550
Kif nista 'nikseb linja ġdida?

994
00:47:57,550 --> 00:47:58,800
>> STUDENT: Backslash n.

995
00:47:58,800 --> 00:48:04,610

996
00:48:04,610 --> 00:48:07,100
>> JASON Hirschhorn: What do I ritorn
jekk runs ewlenin b'mod korrett?

997
00:48:07,100 --> 00:48:08,360
>> STUDENT: 0.

998
00:48:08,360 --> 00:48:09,430
Do I bżonn jiktbu dik il-linja, għalkemm?

999
00:48:09,430 --> 00:48:10,170
>> STUDENT: Le

1000
00:48:10,170 --> 00:48:11,513
OK, aħna mhux se jiktbu, imbagħad.

1001
00:48:11,513 --> 00:48:16,450

1002
00:48:16,450 --> 00:48:17,190
Jista kulħadd taqra li?

1003
00:48:17,190 --> 00:48:18,485
Huwa jistenna ftit żgħira.

1004
00:48:18,485 --> 00:48:20,160
Jista 'kulħadd jaraw, jew jekk
I jagħmilha akbar?

1005
00:48:20,160 --> 00:48:23,480

1006
00:48:23,480 --> 00:48:25,100
Naħseb għall-kamera, aħna ser tagħmel
hija daqsxejn akbar, għalkemm.

1007
00:48:25,100 --> 00:48:35,750

1008
00:48:35,750 --> 00:48:38,410
>> JASON Hirschhorn: Jekk irrid inbiddlu din
. Ċ fajl fis eżekutibbli, liema

1009
00:48:38,410 --> 00:48:39,260
do I jiktbu?

1010
00:48:39,260 --> 00:48:41,610
>> STUDENT: Agħmel test.

1011
00:48:41,610 --> 00:48:42,080
>> JASON Hirschhorn: Jiddispjacini?

1012
00:48:42,080 --> 00:48:42,790
>> STUDENT: Agħmel test.

1013
00:48:42,790 --> 00:48:44,040
>> JASON Hirschhorn: Agħmel test.

1014
00:48:44,040 --> 00:48:46,700

1015
00:48:46,700 --> 00:48:48,410
Konna nitkellmu dwar
din il-linja qabel.

1016
00:48:48,410 --> 00:48:49,140
Clang.

1017
00:48:49,140 --> 00:48:51,270
X'hemm clang?

1018
00:48:51,270 --> 00:48:52,200
L-isem tal-kompilatur.

1019
00:48:52,200 --> 00:48:53,920
X'hemm din il-linja?

1020
00:48:53,920 --> 00:48:55,580
>> STUDENT: Settijiet it up għall-użu ta 'GDB.

1021
00:48:55,580 --> 00:48:59,230
>> JASON Hirschhorn: Settijiet
it up għall-użu ta 'GDB.

1022
00:48:59,230 --> 00:49:02,338
Din il-linja, dak li?

1023
00:49:02,338 --> 00:49:03,290
>> STUDENT: Kodiċi tas-sors.

1024
00:49:03,290 --> 00:49:06,010
>> JASON Hirschhorn: Dik hija l-
sors fajl, il-fajl c..

1025
00:49:06,010 --> 00:49:08,150
What do dawn iż-żewġ linji do?

1026
00:49:08,150 --> 00:49:10,245
Jew dawn iż-żewġ le linji.

1027
00:49:10,245 --> 00:49:12,300
>> STUDENT: Huwa ismijiet li jittestjaw.

1028
00:49:12,300 --> 00:49:15,410
>> JASON Hirschhorn: Allura l-sing o jgħid,
isem li bih xi ħaġa differenti.

1029
00:49:15,410 --> 00:49:16,790
U hawn int ssejjaħ dan it-test.

1030
00:49:16,790 --> 00:49:18,900
Jekk jien ma jkollhom li,
dak li huwa isem dan?

1031
00:49:18,900 --> 00:49:20,260
>> STUDENT: A.out.

1032
00:49:20,260 --> 00:49:22,340
>> JASON Hirschhorn: A.out.

1033
00:49:22,340 --> 00:49:25,366
X'jagħmel din do?

1034
00:49:25,366 --> 00:49:27,670
>> STUDENT: Links il-librerija matematika.

1035
00:49:27,670 --> 00:49:29,550
>> JASON Hirschhorn: Huwa links
fil-librerija matematika.

1036
00:49:29,550 --> 00:49:32,880
Aħna ma kinux jinkludu l-librerija matematika, iżda
peress li hekk komuni, li ħadthom

1037
00:49:32,880 --> 00:49:35,780
make miktub li dejjem tinkludi
il-librerija matematika.

1038
00:49:35,780 --> 00:49:39,050
U bl-istess mod, dan jinkludi
il-librerija CS50.

1039
00:49:39,050 --> 00:49:43,010
>> OK, hekk jekk aħna lista, issa għandna
eżekutibbli imsejħa test.

1040
00:49:43,010 --> 00:49:45,150
Li jiġi esegwit, nikteb test.

1041
00:49:45,150 --> 00:49:48,330
Nara li b'punt li jvarja tiegħi,
kif mistenni, ikun egwali għal 0.

1042
00:49:48,330 --> 00:49:50,890

1043
00:49:50,890 --> 00:49:51,590
Does li -

1044
00:49:51,590 --> 00:49:52,060
hekk -

1045
00:49:52,060 --> 00:49:55,210
>> STUDENT: Imbagħad jekk inti tpoġġi float issa,
bħal inti mitfugħa bħala float -

1046
00:49:55,210 --> 00:49:56,870
>> JASON Hirschhorn: Cast
l-1 għal float?

1047
00:49:56,870 --> 00:49:59,180
>> STUDENT: Le, mitfugħa l-ħaġa sħiħa -

1048
00:49:59,180 --> 00:49:59,500
yeah.

1049
00:49:59,500 --> 00:50:02,460
Jekk inti biss ma li, kieku
li jagħmilha 0.1?

1050
00:50:02,460 --> 00:50:07,170
>> JASON Hirschhorn: OK, sabiex verament malajr,
1 maqsum f'10, dawn huma

1051
00:50:07,170 --> 00:50:08,690
interi qed tiġi diviża.

1052
00:50:08,690 --> 00:50:13,580
Allura meta inti jaqsmu interi, dawn qed
0, u int iffrankar li 0 fil-

1053
00:50:13,580 --> 00:50:17,170
float, minħabba li l-mmejla hi
biss diviżjoni numru sħiħ.

1054
00:50:17,170 --> 00:50:19,180
Allura issa aħna qed iduru xi ħaġa
fi float.

1055
00:50:19,180 --> 00:50:21,650
>> Ejja naraw x'jiġri.

1056
00:50:21,650 --> 00:50:22,900
Aħna ser tagħmel test.

1057
00:50:22,900 --> 00:50:25,870

1058
00:50:25,870 --> 00:50:31,090
Allura issa naraw li dan slash ma kienx
diviżjoni integer, kien f'wiċċ l-ilma

1059
00:50:31,090 --> 00:50:32,640
punt diviżjoni.

1060
00:50:32,640 --> 00:50:35,700
Għaliex wieħed mill-argumenti tagħha
kienu mitfugħa għal float.

1061
00:50:35,700 --> 00:50:38,380
Allura issa huwa kien qal, jittratta din
diviżjoni simili aħna qed jittrattaw ma

1062
00:50:38,380 --> 00:50:40,140
punti f'wiċċ l-ilma, mhux ma interi.

1063
00:50:40,140 --> 00:50:42,760
U hekk irridu jiksbu l-risposta nistennew.

1064
00:50:42,760 --> 00:50:44,620
>> Ejja naraw dak li jiġri -

1065
00:50:44,620 --> 00:50:47,103
oops.

1066
00:50:47,103 --> 00:50:51,646
Jekk jien ridt li jistampaw aktar informazzjoni
spots, kif jista I do dan?

1067
00:50:51,646 --> 00:50:55,550
>> STUDENT: Point dot f, jew kemm
postijiet deċimali kif tixtieq.

1068
00:50:55,550 --> 00:51:02,280

1069
00:51:02,280 --> 00:51:04,440
>> JASON Hirschhorn: So I jistampaw
10 spots deċimali.

1070
00:51:04,440 --> 00:51:06,610
U aħna issa tara aħna jkollna
xi għalf stramb.

1071
00:51:06,610 --> 00:51:09,650
U li tmur lura għall-mistoqsija tiegħek
dwar floating punt impreċiżjoni.

1072
00:51:09,650 --> 00:51:10,950
Hemm Jittieħed stramb maħżuna fil hawn.

1073
00:51:10,950 --> 00:51:13,650

1074
00:51:13,650 --> 00:51:15,275
>> OK, ma li iwieġeb il-mistoqsija tiegħek?

1075
00:51:15,275 --> 00:51:18,550

1076
00:51:18,550 --> 00:51:20,200
X'iktar ma trid
għall-kodiċi malajr?

1077
00:51:20,200 --> 00:51:25,470
>> STUDENT: I ​​biss riedu biex tara jekk jew
le, jekk inti lliberat xi pointer,

1078
00:51:25,470 --> 00:51:30,410
jekk dik pointer xorta kienu maħżuna
it-indirizz ta 'dak li kien

1079
00:51:30,410 --> 00:51:32,170
tipponta lejn qabel.

1080
00:51:32,170 --> 00:51:34,100
>> JASON Hirschhorn: OK,
hekk ejja tagħmel dan.

1081
00:51:34,100 --> 00:51:38,030
Char PTR star, dan joħloq varjabbli
imsejħa PTR tat star char tip.

1082
00:51:38,030 --> 00:51:39,280
Kif nikteb malloc?

1083
00:51:39,280 --> 00:51:40,550
Alden?

1084
00:51:40,550 --> 00:51:41,800
>> ALDEN: Just malloc.

1085
00:51:41,800 --> 00:51:44,820

1086
00:51:44,820 --> 00:51:51,040
Iżda mbagħad għandu jkun id-daqs ta ', u
f'dan il-każ, I raden youd

1087
00:51:51,040 --> 00:51:52,465
tkun tipponta lejn char.

1088
00:51:52,465 --> 00:51:54,450
Għalhekk d jkun char.

1089
00:51:54,450 --> 00:51:57,520
>> JASON Hirschhorn: OK, hekk aktar
ġenerikament, Ġewwa -

1090
00:51:57,520 --> 00:51:58,770
ejja jeditjaw.

1091
00:51:58,770 --> 00:52:05,100

1092
00:52:05,100 --> 00:52:09,260
Ġewwa malloc, inti tixtieq in-numru
ta 'bytes fuq il-borġ.

1093
00:52:09,260 --> 00:52:12,320
Ġeneralment, dak li aħna stajt tidher li aħna qed
tagħmel hu li aħna qed tmur biex malloc

1094
00:52:12,320 --> 00:52:14,940
kordi, per eżempju, jew
arrays tan-numri interi.

1095
00:52:14,940 --> 00:52:21,600
Mela jekk irridu 10 interi, jew 10
Chars, 10 se tagħtina 10.

1096
00:52:21,600 --> 00:52:24,370
U mbagħad daqs tal Chars tagħti
us li d-daqs ta 'Chars, li

1097
00:52:24,370 --> 00:52:25,120
F'dan il-każ huwa 1 byte.

1098
00:52:25,120 --> 00:52:26,250
Nikbru 10 bytes.

1099
00:52:26,250 --> 00:52:28,540
Jekk konna li tikteb daqs ta 'int,
li tagħtina 40 bytes.

1100
00:52:28,540 --> 00:52:31,520
>> Allura aktar ġeneriku, ġewwa ta malloc
huwa n-numru ta 'bytes li trid.

1101
00:52:31,520 --> 00:52:34,620
F'dan il-każ, aħna jkollna 1 byte.

1102
00:52:34,620 --> 00:52:36,900
Li tidher qisha użu stramb
ta malloc, iżda għal tagħna

1103
00:52:36,900 --> 00:52:38,470
skopijiet jagħmel sens.

1104
00:52:38,470 --> 00:52:40,420
Allura hemm dak.

1105
00:52:40,420 --> 00:52:43,420
>> Aħna ser sejħa ħielsa.

1106
00:52:43,420 --> 00:52:47,040
Aħna jeħles minnu u nużaw PTR ġdid.

1107
00:52:47,040 --> 00:52:48,750
U dak li ma inti tixtieq li jiċċekkjaw?

1108
00:52:48,750 --> 00:52:50,550
>> STUDENT: I ​​biss riedu biex tivverifika jekk
jew ma kienx hemm xejn

1109
00:52:50,550 --> 00:52:51,900
ġewwa ta 'dan.

1110
00:52:51,900 --> 00:52:53,050
>> JASON Hirschhorn: Allura jekk
hija enfasizzat li xejn?

1111
00:52:53,050 --> 00:52:57,740
>> STUDENT: Yeah, eżattament, kemm jekk
kien għad għandu l-indirizz tal-memorja.

1112
00:52:57,740 --> 00:53:02,220
>> JASON Hirschhorn: Allura inti tixtieq
biex jiċċekkja l-valur tal-PTR?

1113
00:53:02,220 --> 00:53:03,470
>> STUDENT: Yeah, eżattament.

1114
00:53:03,470 --> 00:53:07,940

1115
00:53:07,940 --> 00:53:10,160
>> JASON Hirschhorn: What do I jiktbu hawn
jekk irrid li jivverifika l-valur tal-

1116
00:53:10,160 --> 00:53:11,880
punt - x'inhu, il-Ġordan
qal, il-valur?

1117
00:53:11,880 --> 00:53:13,720
Jew dak li huwa maħżun ġewwa ta PTR?

1118
00:53:13,720 --> 00:53:14,620
>> STUDENT: A indirizz tal-memorja.

1119
00:53:14,620 --> 00:53:16,330
>> JASON Hirschhorn: A indirizz tal-memorja.

1120
00:53:16,330 --> 00:53:20,520
Mela jekk nikteb biss dan, dan ser
agħtini l-valur tal-PTR.

1121
00:53:20,520 --> 00:53:22,800
U kif nista jistampa
l-indirizz tal-memorja?

1122
00:53:22,800 --> 00:53:26,470
X'hemm-format string
għal indirizz memorja?

1123
00:53:26,470 --> 00:53:27,430
>> STUDENT:% p.

1124
00:53:27,430 --> 00:53:28,050
>> JASON Hirschhorn:% p.

1125
00:53:28,050 --> 00:53:29,500
% S huwa string.

1126
00:53:29,500 --> 00:53:30,750
% P għall pointer.

1127
00:53:30,750 --> 00:53:40,820

1128
00:53:40,820 --> 00:53:43,540
Huwa dan id-dritt?

1129
00:53:43,540 --> 00:53:44,790
Dan huwa dritt.

1130
00:53:44,790 --> 00:53:49,450

1131
00:53:49,450 --> 00:53:51,040
Allura PTR ugwali -

1132
00:53:51,040 --> 00:53:53,350
xorta għandu xi ħaġa fiha.

1133
00:53:53,350 --> 00:53:56,110

1134
00:53:56,110 --> 00:53:57,645
Din hija probabbilment aktar
mistoqsija interessanti.

1135
00:53:57,645 --> 00:53:59,198
X'jagħmel din il-linja tagħmel?

1136
00:53:59,198 --> 00:54:00,830
>> STUDENT: difetti seg.

1137
00:54:00,830 --> 00:54:01,310
>> JASON Hirschhorn: What?

1138
00:54:01,310 --> 00:54:02,678
>> STUDENT: Naħseb li SEG ħsarat.

1139
00:54:02,678 --> 00:54:03,574
>> JASON Hirschhorn: Hm?

1140
00:54:03,574 --> 00:54:04,920
>> STUDENT: Naħseb li ser seg tort.

1141
00:54:04,920 --> 00:54:08,265
>> JASON Hirschhorn: Allura din il-linja
ta PTR kodiċi, star, liema

1142
00:54:08,265 --> 00:54:10,152
ma l-istilla jfisser?

1143
00:54:10,152 --> 00:54:11,240
>> STUDENT: Kontenut ta '.

1144
00:54:11,240 --> 00:54:11,560
>> JASON Hirschhorn: Yeah.

1145
00:54:11,560 --> 00:54:13,910
Mur jiksbu l-kontenut ta '.

1146
00:54:13,910 --> 00:54:16,830
Allura dan se jmorru għall-memorja
jindirizzaw hemm u tagħti me dak.

1147
00:54:16,830 --> 00:54:21,030
I użati% c dritt hawn għaliex hemm
huma karattri maħżuna hemmhekk.

1148
00:54:21,030 --> 00:54:23,390
Allura aħna qed tmur biex tmur f'dak indirizz aħna
biss raw - jew inneħħu probabbilment tkun

1149
00:54:23,390 --> 00:54:25,190
ftit dan differenti
żmien we run-programm.

1150
00:54:25,190 --> 00:54:28,010
Iżda aħna ser imorru f'dak l-indirizz
li nafu għadu jeżisti

1151
00:54:28,010 --> 00:54:29,260
u tara x'hemm hemmhekk.

1152
00:54:29,260 --> 00:54:35,640

1153
00:54:35,640 --> 00:54:37,110
>> Għalhekk hija ma seg tort.

1154
00:54:37,110 --> 00:54:38,970
Hija biss ma tagħtina xejn.

1155
00:54:38,970 --> 00:54:43,350
Jista 'jkunu attwalment tawna
xi ħaġa, aħna biss ma tistax tara dan.

1156
00:54:43,350 --> 00:54:45,110
U li tmur lura għal din l-idea -

1157
00:54:45,110 --> 00:54:47,270
u aħna qed mhux se tikseb wisq fis
dan, minħabba li l hinn mill-

1158
00:54:47,270 --> 00:54:48,460
ambitu ta 'dan il-kors.

1159
00:54:48,460 --> 00:54:51,260
Iżda tkellimna dwar dritt hawn, jekk aħna
marru lil hinn mill-limiti ta 'l-array

1160
00:54:51,260 --> 00:54:54,890
1, aħna ma tista 'tikseb fl-inkwiet.

1161
00:54:54,890 --> 00:54:58,550
>> Xi kultant, meta inti biss jmorru off b'1,
int tagħmel xi ħaġa ħażina, u inti

1162
00:54:58,550 --> 00:54:59,220
setgħux jiksbu fl-inkwiet.

1163
00:54:59,220 --> 00:55:00,820
Imma inti ma dejjem jiksbu fl-inkwiet.

1164
00:55:00,820 --> 00:55:05,170
Hija tiddependi kemm ta 'ħaġa ħażina inti
do, int ser tikseb fl-inkwiet.

1165
00:55:05,170 --> 00:55:07,790
Liema hija ma jfissirx, tkun sloppy
bil-kodiċi tiegħek.

1166
00:55:07,790 --> 00:55:12,080
Iżda huwa jiġifieri, il-programm mhux se
dejjem nieqaf, anki jekk inti tmur x'imkien

1167
00:55:12,080 --> 00:55:14,130
int mhux suppost li jmorru.

1168
00:55:14,130 --> 00:55:18,170
>> Eżempju tajjeb ta 'dan huwa, lott ta'
nies fil-problema tagħhom stabbiliti 3, li

1169
00:55:18,170 --> 00:55:22,350
kien 15, ma eżaminawx il-
limiti tal-bord.

1170
00:55:22,350 --> 00:55:25,860
Allura inti ħares lejn ix-xellug, ħarsu l-
dritt, ħares lejn il-wiċċ, ħares

1171
00:55:25,860 --> 00:55:27,000
mal-qiegħ.

1172
00:55:27,000 --> 00:55:31,540
Imma inti ma tikkontrolla biex tara jekk il-quċċata
kien fil-fatt se tkun fuq il-bord.

1173
00:55:31,540 --> 00:55:35,220
U ħafna nies li għamlu dan u
daru li, programm tagħhom ħadmu

1174
00:55:35,220 --> 00:55:38,960
perfettament, minħabba fejn dak il-bord kien
maħżuna fil-memorja, jekk inti marru wieħed

1175
00:55:38,960 --> 00:55:42,300
hawn fuq jew ikun iċċekkjat li l-memorja
indirizz, ma kien hemm xejn

1176
00:55:42,300 --> 00:55:44,870
partikolarment horrible dwar dan,
hekk program tiegħek ma kienx

1177
00:55:44,870 --> 00:55:45,970
se Yell fi inti.

1178
00:55:45,970 --> 00:55:48,870
>> Iżda aħna xorta se tieħu off punti jekk
inti ma tivverifika li, minħabba li inti

1179
00:55:48,870 --> 00:55:50,850
kienu qed jagħmlu xi ħaġa inti ma kinux
suppost tagħmel, u inti jista 'jkollhom

1180
00:55:50,850 --> 00:55:51,860
gotten fl-inkwiet.

1181
00:55:51,860 --> 00:55:54,040
Odds huma, għalkemm, inti probabilment ma.

1182
00:55:54,040 --> 00:55:57,790
Allura dan huwa li turi li, iva,
aħna xorta tista 'tmur għaliha.

1183
00:55:57,790 --> 00:55:59,010
U aħna mhux qed jkollna fil-
trouble f'dan il-każ.

1184
00:55:59,010 --> 00:56:04,000
Jekk aħna ppruvaw jagħmlu taqra l-
100 karattri li jmiss, aħna'd

1185
00:56:04,000 --> 00:56:06,000
probabbilment nikseb fl-inkwiet.

1186
00:56:06,000 --> 00:56:09,400
U inti tista kodiċi qari tal-100 li jmiss
karattri jekk inti tixtieq billi tagħmel xi

1187
00:56:09,400 --> 00:56:10,110
tip ta 'għal loop.

1188
00:56:10,110 --> 00:56:10,850
Yeah.

1189
00:56:10,850 --> 00:56:16,250
>> STUDENT: Minħabba li aħna ġew assenjati li
ispazju ta 'valur attwali, aħna mhux se

1190
00:56:16,250 --> 00:56:17,050
attwalment tkun tista 'tara xejn.

1191
00:56:17,050 --> 00:56:21,740
Jekk nippruvaw bl-istabbiliment li
daqs simili c jew xi ħaġa?

1192
00:56:21,740 --> 00:56:22,640
>> JASON Hirschhorn: mistoqsija Great.

1193
00:56:22,640 --> 00:56:25,340
Kif nista 'valur -

1194
00:56:25,340 --> 00:56:28,980
liema linja tal-kodiċi nista jiktbu fuq il-linja
seba 'tagħmel dak li qal?

1195
00:56:28,980 --> 00:56:34,040
>> STUDENT: Star PTR ugwali wieħed
quote ċ jispiċċaw kwotazzjoni waħda.

1196
00:56:34,040 --> 00:56:36,970
>> JASON Hirschhorn: Allura thats tqegħid
karattru, c, f'dak il-post,

1197
00:56:36,970 --> 00:56:40,200
għaliex għal darb'oħra, li star
ifisser mur hemm.

1198
00:56:40,200 --> 00:56:43,320
U meta jintużaw fuq in-naħa tax-xellug tal-
operatur assenjazzjoni, li jkun daqs

1199
00:56:43,320 --> 00:56:47,270
tiffirma, aħna mhux se tikseb dak
valur tant kif stabbilit dak il-valur.

1200
00:56:47,270 --> 00:56:48,520
Issa ejja naraw x'jiġri.

1201
00:56:48,520 --> 00:56:54,700

1202
00:56:54,700 --> 00:56:56,770
>> Npoġġux xi ħaġa hemmhekk
u kien hemm.

1203
00:56:56,770 --> 00:56:58,000
Aħna imsejħa ħielsa.

1204
00:56:58,000 --> 00:57:00,100
Xi għalf probabbilment ġara
fuq il-borġ.

1205
00:57:00,100 --> 00:57:01,890
Dan mhuwiex hemm aktar.

1206
00:57:01,890 --> 00:57:07,440
Iżda għal darb'oħra, aħna mhux qed jkollna
fl-inkwiet biex imur hemmhekk.

1207
00:57:07,440 --> 00:57:10,260
>> Jien tagħmel dan fil-kodiċi li juru
li ħafna ta 'dawn

1208
00:57:10,260 --> 00:57:12,410
mistoqsijiet li għandek, dawn qed
tassew interessanti

1209
00:57:12,410 --> 00:57:13,650
tweġibiet ħafna ħin.

1210
00:57:13,650 --> 00:57:15,260
U dawn qed mistoqsijiet verament tajba.

1211
00:57:15,260 --> 00:57:19,010
U inti tista 'figura out fuq
stess jekk tiegħek, per eżempju,

1212
00:57:19,010 --> 00:57:19,990
aħna mhux qed f'sezzjoni.

1213
00:57:19,990 --> 00:57:20,940
Yeah.

1214
00:57:20,940 --> 00:57:24,430
>> STUDENT: Minħabba int ma tibgħat il-
pointer kullimkien, do għandek bżonn

1215
00:57:24,430 --> 00:57:26,530
użu malloc?

1216
00:57:26,530 --> 00:57:28,400
>> JASON Hirschhorn: Allura dan imur lura
għall-mistoqsija inizjali tiegħek.

1217
00:57:28,400 --> 00:57:28,620
[? ?]

1218
00:57:28,620 --> 00:57:29,980
Hija biss varjabbli lokali?

1219
00:57:29,980 --> 00:57:32,280
Malloc hawnhekk mhuwiex dak konvinċenti.

1220
00:57:32,280 --> 00:57:35,260
L-użu ta malloc hawnhekk mhix
li konvinċenti għaliex dan huwa

1221
00:57:35,260 --> 00:57:36,500
biss varjabbli lokali.

1222
00:57:36,500 --> 00:57:40,970
>> STUDENT: Allura inti tista 'tagħmel char
PTR star ugwali bonjour?

1223
00:57:40,970 --> 00:57:41,400
>> JASON Hirschhorn: Oh.

1224
00:57:41,400 --> 00:57:43,300
Allura aħna qed tmur biex issa jiksbu lura
għall-mistoqsija inizjali tiegħek.

1225
00:57:43,300 --> 00:57:46,885
I think inti ma kinux sodisfatti
bit-tweġiba tiegħi.

1226
00:57:46,885 --> 00:57:48,220
OK?

1227
00:57:48,220 --> 00:57:49,226
Bħal dik?

1228
00:57:49,226 --> 00:57:49,682
>> STUDENT: Yeah.

1229
00:57:49,682 --> 00:57:50,932
Stenna.

1230
00:57:50,932 --> 00:57:54,090

1231
00:57:54,090 --> 00:57:57,850
>> JASON Hirschhorn: U fejn
tridu li jistampa?

1232
00:57:57,850 --> 00:58:00,026
Allura aħna ser jistampa string bħal dik?

1233
00:58:00,026 --> 00:58:06,380

1234
00:58:06,380 --> 00:58:07,630
>> STUDENT: Interessanti.

1235
00:58:07,630 --> 00:58:09,900

1236
00:58:09,900 --> 00:58:14,285
>> JASON Hirschhorn: Allura dan jgħid dan
argument għandu l-tip ta 'karattru.

1237
00:58:14,285 --> 00:58:17,200

1238
00:58:17,200 --> 00:58:18,620
Għalhekk dan għandu jkun karattru.

1239
00:58:18,620 --> 00:58:25,170

1240
00:58:25,170 --> 00:58:26,280
>> STUDENT: Just tieħu l-ewwel waħda.

1241
00:58:26,280 --> 00:58:28,610
>> JASON Hirschhorn: Allura dan
huwa dak li għidt qabel.

1242
00:58:28,610 --> 00:58:34,240
Like I said, mhuwiex ħażna tal-
string ġewwa pointer varjabbli.

1243
00:58:34,240 --> 00:58:35,120
Huwa ħażna -

1244
00:58:35,120 --> 00:58:36,350
>> STUDENT: L-ewwel valur
tas-sekwenza.

1245
00:58:36,350 --> 00:58:40,810
>> JASON Hirschhorn: L-indirizz ta '
l-ewwel valur tas-sekwenza.

1246
00:58:40,810 --> 00:58:46,940
Jekk konna li jistampa dan, aħna qed
jkollna l-valur ġewwa pointer.

1247
00:58:46,940 --> 00:58:51,005
U aħna ser tara huwa, tabilħaqq,
l-indirizz tal-memorja.

1248
00:58:51,005 --> 00:58:53,595

1249
00:58:53,595 --> 00:58:56,440
>> Does li jagħmel sens?

1250
00:58:56,440 --> 00:58:56,940
Jiddispjacini.

1251
00:58:56,940 --> 00:58:58,996
Stenna, ma li twieġeb tiegħek
kwistjoni, għalkemm?

1252
00:58:58,996 --> 00:58:59,790
>> STUDENT: Yeah.

1253
00:58:59,790 --> 00:59:05,830
>> JASON Hirschhorn: Din il-linja tal-kodiċi
ħolqien ta 'spag u mbagħad ieħor

1254
00:59:05,830 --> 00:59:09,115
pointer varjabbli thats tipponta
għal dak string, li array.

1255
00:59:09,115 --> 00:59:14,320

1256
00:59:14,320 --> 00:59:14,980
Yeah.

1257
00:59:14,980 --> 00:59:19,200
>> STUDENT: Mela jekk aħna marru memorja wieħed
tkompli tindirizza, kieku aħna jiksbu l-h?

1258
00:59:19,200 --> 00:59:21,990

1259
00:59:21,990 --> 00:59:23,150
Ma kienu maħżuna bħala string?

1260
00:59:23,150 --> 00:59:24,400
>> JASON Hirschhorn: Bħal, għamilna -

1261
00:59:24,400 --> 00:59:28,540

1262
00:59:28,540 --> 00:59:30,790
għalhekk dan huwa importanti li tagħmel.

1263
00:59:30,790 --> 00:59:33,780
Dan huwa punt aritmetika, li inti guys
raw qabel u għandhom ikunu

1264
00:59:33,780 --> 00:59:35,550
relattivament komdi.

1265
00:59:35,550 --> 00:59:36,905
Dan huwa simili għall-kitba -

1266
00:59:36,905 --> 00:59:41,980

1267
00:59:41,980 --> 00:59:46,350
jekk konna li tikteb din il-linja ta 'kodiċi,
Rajna notazzjoni array qabel.

1268
00:59:46,350 --> 00:59:55,900
Dan għandu tagħtina t-tieni
valur f'dan il-firxa, h.

1269
00:59:55,900 --> 01:00:05,010
>> Jekk aħna ma dan, dan għandu wkoll jagħti
us-tieni valur f'dak array.

1270
01:00:05,010 --> 01:00:08,320
Minħabba li huwa għaddej ma 'l-memorja
indirizz ta 'l-ewwel ħaġa, iżda l-

1271
01:00:08,320 --> 01:00:10,530
indirizz tal-memorja tal-ħaġa waħda fuq.

1272
01:00:10,530 --> 01:00:14,360
U allura l-dereferences operatur star
li pointer.

1273
01:00:14,360 --> 01:00:16,940
U għal darb'oħra, ejja ara.

1274
01:00:16,940 --> 01:00:18,664
Nikbru h ġdid.

1275
01:00:18,664 --> 01:00:20,980
>> STUDENT: X'inhuma eżattament ma
dereference jfisser?

1276
01:00:20,980 --> 01:00:23,650
>> JASON Hirschhorn: Dereference
hija kelma fancy għall tmur.

1277
01:00:23,650 --> 01:00:26,390
Mur dan u tikseb x'hemm hemmhekk
huwa li dereference pointer.

1278
01:00:26,390 --> 01:00:28,240
Huwa biss kelma fancy għal dan.

1279
01:00:28,240 --> 01:00:29,986
>> STUDENT: Jekk ridna li jistampaw
l-sekwenza sħiħa, nistgħu

1280
01:00:29,986 --> 01:00:31,930
do pointer ampersand?

1281
01:00:31,930 --> 01:00:33,490
>> JASON Hirschhorn: OK, aħna
se nieqaf hawn.

1282
01:00:33,490 --> 01:00:35,480
Aħna ser jieqafx hawn.

1283
01:00:35,480 --> 01:00:41,760
Ampersand jagħtik l-indirizz ta '
post, hekk meta inti tagħmel ampersand ta '

1284
01:00:41,760 --> 01:00:44,080
varjabbli, li tagħtik l-indirizz
fejn dak il-varjabbli huwa maħżun.

1285
01:00:44,080 --> 01:00:48,580
Pointer ampersand se jagħtik l-
indirizz tal-PTR fejn ptr huwa fil-memorja.

1286
01:00:48,580 --> 01:00:50,140
>> Aħna mhux se jmorru fuq
ma 'dan l-eżempju.

1287
01:00:50,140 --> 01:00:52,640
Inti tista figura out dawn
affarijiet fuq tiegħek.

1288
01:00:52,640 --> 01:00:55,740
Iżda għal darb'oħra, dan jista 'anke jkun verging a
bit hinn minn dak li għandek bżonn tkun taf għal

1289
01:00:55,740 --> 01:00:58,000
l-ambitu ta 'dan nofs it-terminu -

1290
01:00:58,000 --> 01:00:59,070
jew dan il-kwizz, pjuttost.

1291
01:00:59,070 --> 01:01:00,270
Jiddispjacini.

1292
01:01:00,270 --> 01:01:03,770
>> Aħna ser jimxu fuq, minħabba I kieku
tixtieq tagħmel problema waħda kodifikazzjoni

1293
01:01:03,770 --> 01:01:05,100
qabel il-ħin huwa up.

1294
01:01:05,100 --> 01:01:09,340
U aħna ser kodiċi dak li naħseb
hija l-aktar konvinċenti ta 'dawn

1295
01:01:09,340 --> 01:01:11,020
eżempji, atoi.

1296
01:01:11,020 --> 01:01:14,520
Għalhekk din kienet mistoqsija dwar
kwizz sentejn ilu.

1297
01:01:14,520 --> 01:01:17,810
U I jkollhom fuq il-bord hawn.

1298
01:01:17,810 --> 01:01:20,680
>> In-nies kienu mitluba fuq l-kwizz -

1299
01:01:20,680 --> 01:01:23,640
dawn ingħataw ftit aktar tesxt fl
il-kwistjoni, iżda I eliminati l-

1300
01:01:23,640 --> 01:01:26,640
test għaliex ma kienx meħtieġ
għall-għanijiet tagħna issa.

1301
01:01:26,640 --> 01:01:29,180
Kien biss xi isfond
fuq dak atoi għamlet.

1302
01:01:29,180 --> 01:01:31,425
Imma you know kollha u huma ħafna
familjari ma atoi.

1303
01:01:31,425 --> 01:01:35,620
>> Nissuġġerixxi inti kodiċi dan
fuq folja tal-karta.

1304
01:01:35,620 --> 01:01:39,310
I jissuġġerixxu wkoll li tuża l-istrateġija
li konna marret fuq

1305
01:01:39,310 --> 01:01:41,040
ħafna fis-sezzjoni tagħna.

1306
01:01:41,040 --> 01:01:44,130
L-ewwel, aċċerta ruħek li tifhem
ta dak atoi tagħmel.

1307
01:01:44,130 --> 01:01:47,580
Pinġi stampa jew toħroġ b'xi
immaġni ta 'dan fir-ras.

1308
01:01:47,580 --> 01:01:51,120
Sussegwentement, jiktbu pseudocode għal dan.

1309
01:01:51,120 --> 01:01:53,120
Fuq l-kwizz, jekk kollha ikollok huwa
pseudocode, mill-inqas int

1310
01:01:53,120 --> 01:01:54,550
xi ħaġa down.

1311
01:01:54,550 --> 01:02:00,070
U mbagħad mappa li pseudocode fuq
C. Jekk għandek check-in tiegħek

1312
01:02:00,070 --> 01:02:03,760
pseudocode, bħal jiċċekkjaw jekk xi ħaġa
huwa 1, li l-mapep fuq IF

1313
01:02:03,760 --> 01:02:05,750
kondizzjoni u ibqa 'sejjer hekk.

1314
01:02:05,750 --> 01:02:07,850
U fl-aħħarnett, il-kodiċi tal-programm C.

1315
01:02:07,850 --> 01:02:15,000
>> Allura jmorru lura għall atoi u tieħu ħames minuti
għall-kodiċi dan fuq folja tal-

1316
01:02:15,000 --> 01:02:19,480
karta, li probabbilment hija dwar l-
ammont ta 'ħin li inti se tieħu fuq

1317
01:02:19,480 --> 01:02:21,260
kwizz biex atoi kodiċi.

1318
01:02:21,260 --> 01:02:27,060
Ta 'ħames sa 15 minuta, ħames sa 12, ħames sa
10 minuta, huwa dwar l-ammont ta '

1319
01:02:27,060 --> 01:02:30,150
ħin youd jonfqu fuq dan
kwistjoni fil-kwizz.

1320
01:02:30,150 --> 01:02:31,670
Sabiex jieħdu ħames minuti issa, jekk jogħġbok.

1321
01:02:31,670 --> 01:02:35,957
U jekk għandek xi mistoqsijiet, iqajmu
idejn tiegħek u jien ser jidħlu madwar.

1322
01:02:35,957 --> 01:06:39,570

1323
01:06:39,570 --> 01:06:41,066
>> [konversazzjonijiet SEKONDARJI]

1324
01:06:41,066 --> 01:08:35,279

1325
01:08:35,279 --> 01:08:37,580
>> JASON Hirschhorn: OK, so
li kien ta 'ħames minuti.

1326
01:08:37,580 --> 01:08:39,880
Dan kien probabbilment dwar l-ammont ta '
ħin youd jonfqu fuq dik fuq kwizz,

1327
01:08:39,880 --> 01:08:42,120
forsi l-aħħar baxxa ta 'dak iż-żmien.

1328
01:08:42,120 --> 01:08:44,010
Aħna ser terġa fi ftit.

1329
01:08:44,010 --> 01:08:45,740
Let us tibda kodifikazzjoni dan.

1330
01:08:45,740 --> 01:08:49,479
U jekk aħna ma jsibux it-triq kollha permezz,
it-tweġibiet għal dan u din

1331
01:08:49,479 --> 01:08:54,189
mistoqsija kwizz huma disponibbli, għal darb'oħra,
Fall 2011 meta din il-mistoqsija

1332
01:08:54,189 --> 01:08:54,913
deher fuq il-kwizz.

1333
01:08:54,913 --> 01:08:57,830
>> U kien jiswa tmien punti
fuq il-kwizz imbagħad.

1334
01:08:57,830 --> 01:09:01,140
Tmien punti huwa fuq il-tarf għoli tal-
ammont ta 'punti xi ħaġa min.

1335
01:09:01,140 --> 01:09:04,790
Mistoqsijiet l-aktar huma fil-medda
ta '1-6 punti.

1336
01:09:04,790 --> 01:09:08,500
Allura dan huwa aktar ta 'sfida
kwistjoni, għall-żgur.

1337
01:09:08,500 --> 01:09:09,750
Jista 'xi ħadd nikseb me bdiet?

1338
01:09:09,750 --> 01:09:13,260

1339
01:09:13,260 --> 01:09:15,380
>> Ġeneralment, liema huma aħna se
trid tagħmel ma 'dan

1340
01:09:15,380 --> 01:09:17,550
jiffunzjonaw atoi, loġikament?

1341
01:09:17,550 --> 01:09:19,569
What do rridu nagħmlu?

1342
01:09:19,569 --> 01:09:22,279
Allura aħna qed tmur biex jiktbu
xi pseudocode.

1343
01:09:22,279 --> 01:09:24,090
>> STUDENT: Ikkonverti karattri
fis interi.

1344
01:09:24,090 --> 01:09:26,700
>> JASON Hirschhorn: Ikkonverti karattri
fis interi.

1345
01:09:26,700 --> 01:09:27,479
OK.

1346
01:09:27,479 --> 01:09:30,870
Allura kif ħafna karattri aħna
ser jeħtieġ li jmorru permezz?

1347
01:09:30,870 --> 01:09:32,295
>> STUDENT: Kollha kemm huma.

1348
01:09:32,295 --> 01:09:34,100
>> STUDENT: Il-karattri
fis-sekwenza.

1349
01:09:34,100 --> 01:09:35,540
>> JASON Hirschhorn: Kollha tal-
karattri fit-sekwenza.

1350
01:09:35,540 --> 01:09:42,180
Hekk jekk ridna li jmorru permezz ta 'kull
karattru string, liema hija ħaġa

1351
01:09:42,180 --> 01:09:44,560
fl C Rajna li ppermettiet
us li jmorru permezz ta 'kull

1352
01:09:44,560 --> 01:09:45,939
karattru string?

1353
01:09:45,939 --> 01:09:46,819
>> STUDENTI: A għall-loop.

1354
01:09:46,819 --> 01:09:48,069
>> JASON Hirschhorn: A għall-loop.

1355
01:09:48,069 --> 01:09:52,020

1356
01:09:52,020 --> 01:09:55,330
Allura aħna qed tmur biex loop permezz
kull karattru fl-i.

1357
01:09:55,330 --> 01:10:00,940
>> Imbagħad dak li aħna ser trid tagħmel
meta nikbru karattru speċifiku?

1358
01:10:00,940 --> 01:10:02,480
Say aħna qed jkollna għadda 90.

1359
01:10:02,480 --> 01:10:03,460
Irridu jiksbu l-9.

1360
01:10:03,460 --> 01:10:04,240
Huwa karattru.

1361
01:10:04,240 --> 01:10:07,440
What do rridu nagħmlu ma '
li l-karattru 9?

1362
01:10:07,440 --> 01:10:10,082
>> STUDENT: Naqqas minn karattru 0?

1363
01:10:10,082 --> 01:10:11,860
>> STUDENT: Żid 0?

1364
01:10:11,860 --> 01:10:13,350
>> JASON Hirschhorn: Naqqas
minn karattru 0?

1365
01:10:13,350 --> 01:10:13,800
>> STUDENT: Yeah.

1366
01:10:13,800 --> 01:10:15,573
>> JASON Hirschhorn: Why do
inti trid tagħmel dan?

1367
01:10:15,573 --> 01:10:16,560
>> STUDENT: [inaudible]

1368
01:10:16,560 --> 01:10:17,010
valur.

1369
01:10:17,010 --> 01:10:18,380
Valur int tagħha.

1370
01:10:18,380 --> 01:10:21,580
>> JASON Hirschhorn: OK, hekk aħna jieħdu l-
karattru 9, naqqas minn

1371
01:10:21,580 --> 01:10:25,820
karattru 0 biex tikseb
integer attwali 9.

1372
01:10:25,820 --> 01:10:27,070
Sweet.

1373
01:10:27,070 --> 01:10:31,255

1374
01:10:31,255 --> 01:10:37,000
U kif tkun taf li l-karattru
9 nieqes 0 karattru huwa 9?

1375
01:10:37,000 --> 01:10:39,222
What chart ma inti tħares lejn?

1376
01:10:39,222 --> 01:10:43,130
>> STUDENT: Hemm loġikament disa
postijiet bejn 9 u 0.

1377
01:10:43,130 --> 01:10:44,620
Jew inti tista 'tħares lejn il-mejda ASCII.

1378
01:10:44,620 --> 01:10:45,120
>> JASON Hirschhorn: tabella ASCII.

1379
01:10:45,120 --> 01:10:46,490
Imma iva, int korretta ukoll.

1380
01:10:46,490 --> 01:10:47,780
Allura aħna naqqas 0.

1381
01:10:47,780 --> 01:10:49,010
Allura issa għandna l-eqreb numru sħiħ 9.

1382
01:10:49,010 --> 01:10:49,970
U dak li rridu nagħmlu ma 'dak?

1383
01:10:49,970 --> 01:10:54,970
Jekk aħna għandna 90, huwa l-ewwel numru sħiħ
aħna, dak li rridu nagħmlu?

1384
01:10:54,970 --> 01:10:58,180
>> STUDENT: I ​​d tpoġġi fil integer temporanju
array, imbagħad jagħmlu matematika lilha

1385
01:10:58,180 --> 01:11:02,088
aktar tard biex jagħmluha fis tmiem.

1386
01:11:02,088 --> 01:11:03,020
>> JASON Hirschhorn: OK.

1387
01:11:03,020 --> 01:11:06,990
>> STUDENT: Tista 'tibda fi tmiem l-
il-firxa u mbagħad jimxu 'l quddiem sabiex

1388
01:11:06,990 --> 01:11:10,350
li kull darba li inti timxi 'l quddiem,
inti immoltiplika lilha mill 10.

1389
01:11:10,350 --> 01:11:10,830
>> JASON Hirschhorn: OK.

1390
01:11:10,830 --> 01:11:12,250
Li tinstema 'bħala pretty
idea konvinċenti.

1391
01:11:12,250 --> 01:11:16,040
Nistgħu jibda fl-aħħar ta 'firxa tagħna,
u nistgħu nużaw strleng.

1392
01:11:16,040 --> 01:11:17,030
Nistgħu nużaw strleng fil hawn.

1393
01:11:17,030 --> 01:11:18,870
Aħna ser jiksbu l-tul ta 'sekwenza tagħna.

1394
01:11:18,870 --> 01:11:20,100
Nibdew fl-aħħar.

1395
01:11:20,100 --> 01:11:29,170
U + l-ewwel waħda, aħna biss jieħdu dik
numru sħiħ, u forsi noħolqu bħal

1396
01:11:29,170 --> 01:11:32,270
varjabbli ġdid integer top up fejn
aħna qed ħażna kollox.

1397
01:11:32,270 --> 01:11:37,340
Allura aħna loop permezz ta 'kull char fl-i minn
wara quddiem, aħna naqqas 0, u

1398
01:11:37,340 --> 01:11:42,790
allura aħna teħodha, u jiddependi fuq
fejn hi, aħna immoltiplika lilha

1399
01:11:42,790 --> 01:11:45,860
minn qawwa ta '10.

1400
01:11:45,860 --> 01:11:50,644
Minħabba li l-ewwel waħda, liema do we
immoltiplika l-karattru lemini minn?

1401
01:11:50,644 --> 01:11:51,440
>> STUDENT: 10 sa 0.

1402
01:11:51,440 --> 01:11:53,170
>> JASON Hirschhorn: 10 sa 0.

1403
01:11:53,170 --> 01:11:56,010
What do we immoltiplika t-tieni
karattru lemini minn?

1404
01:11:56,010 --> 01:11:57,450
>> STUDENT: [inaudible].

1405
01:11:57,450 --> 01:11:57,960
>> JASON Hirschhorn: What?

1406
01:11:57,960 --> 01:11:59,150
>> STUDENT: 10 sa l-1.

1407
01:11:59,150 --> 01:12:00,420
>> JASON Hirschhorn: 10 sa l-1.

1408
01:12:00,420 --> 01:12:03,754
Il-karattru lemini terz?

1409
01:12:03,754 --> 01:12:04,580
>> STUDENT: 10 għall-2.

1410
01:12:04,580 --> 01:12:05,350
>> JASON Hirschhorn: 10 għall-2.

1411
01:12:05,350 --> 01:12:07,200
>> STUDENT: Skużani jien ma nifhimx
dak li aħna qed tagħmel hawn.

1412
01:12:07,200 --> 01:12:08,640
>> JASON Hirschhorn: OK,
ejja mmorru lura, imbagħad.

1413
01:12:08,640 --> 01:12:12,500
Allura aħna qed tmur biex tikseb
għadda fi string.

1414
01:12:12,500 --> 01:12:14,470
Għaliex aħna qed miktub atoi.

1415
01:12:14,470 --> 01:12:15,260
Allura aħna nikseb għadda fi string.

1416
01:12:15,260 --> 01:12:17,640
Say aħna qed jkollna għadda
fis-sekwenza 90.

1417
01:12:17,640 --> 01:12:19,930
>> L-ewwel ħaġa aħna qed tmur biex tagħmel huwa stabbilit
varjabbli integer ġdid li aħna qed

1418
01:12:19,930 --> 01:12:22,150
biss se toħloq
bħala numru sħiħ ġdida tagħna.

1419
01:12:22,150 --> 01:12:24,630
Dak hu li aħna qed tmur
li jirritornaw fl-aħħar.

1420
01:12:24,630 --> 01:12:30,110
Għandna bżonn li jmorru permezz ta 'kull karattru
l-sekwenza għaliex konna determinati

1421
01:12:30,110 --> 01:12:34,430
li għandna bżonn biex imissu kull wieħed u
imbagħad żid lill integer ġdida tagħna.

1422
01:12:34,430 --> 01:12:36,330
>> Iżda aħna ma tistax żid ftit bħala numru.

1423
01:12:36,330 --> 01:12:38,270
Ma nistgħux sempliċement jieħu 9 u
żid 9 sa numru sħiħ tagħna.

1424
01:12:38,270 --> 01:12:40,560
Hija tiddependi fuq liema post
huwa fl-sekwenza.

1425
01:12:40,560 --> 01:12:42,960
Aħna ser jeħtieġ li jimmultiplikaw
lilha minn qawwa ta '10.

1426
01:12:42,960 --> 01:12:45,580
Minħabba li kif 10 xogħlijiet bażi.

1427
01:12:45,580 --> 01:12:49,050
>> Allura aħna qed tmur biex tikseb l-attwali
karattru, jew id-integer attwali

1428
01:12:49,050 --> 01:12:53,860
numru, billi jitnaqqas karattru 0
minn karattru 9 bħal għamilna mal-

1429
01:12:53,860 --> 01:12:57,560
jitnaqqas karattru kapital A minn
kwalunkwe karattru kellna f'waħda

1430
01:12:57,560 --> 01:12:58,120
dawk il-problemi.

1431
01:12:58,120 --> 01:13:04,190
Allura aħna ser fil-fatt tikseb numru minn 0 sa
9 ffrankati bħala numru reali, u aħna ser

1432
01:13:04,190 --> 01:13:07,590
immoltiplika lilha mill qawwa ta '10ħ jiddependi
fuq fejn ninsabu fis-sekwenza.

1433
01:13:07,590 --> 01:13:19,430

1434
01:13:19,430 --> 01:13:22,575
U allura aħna qed tmur biex iżżid lura
fil-varjabbli tagħna integer ġdid.

1435
01:13:22,575 --> 01:13:32,840

1436
01:13:32,840 --> 01:13:37,890
>> Allura dak li dan look like kieku
jkun - aħna ser tiġbed aktar hawn.

1437
01:13:37,890 --> 01:13:40,086
Jekk aħna jiksbu għadda fis-sekwenza 90 -

1438
01:13:40,086 --> 01:13:41,336
>> STUDENT: [inaudible].

1439
01:13:41,336 --> 01:13:43,190

1440
01:13:43,190 --> 01:13:45,540
>> JASON Hirschhorn: Imma
atoi tieħu string.

1441
01:13:45,540 --> 01:13:46,350
Allura aħna qed tmur biex jgħaddu
l-azjenda.

1442
01:13:46,350 --> 01:13:49,900
Aħna ser jiksbu għadda fil-90.

1443
01:13:49,900 --> 01:13:51,540
Immorru mill-dahar għall-quddiem.

1444
01:13:51,540 --> 01:13:53,920
Nieħdu l-0.

1445
01:13:53,920 --> 01:13:55,080
>> STUDENT: Jien sorry.

1446
01:13:55,080 --> 01:13:55,880
Forsi dan huwa stupid.

1447
01:13:55,880 --> 01:13:59,440
Jekk aħna qed jkollna għadda fi string,
għaliex huwa 90 dak li aħna qed

1448
01:13:59,440 --> 01:14:00,260
jkollna għadda fil-?

1449
01:14:00,260 --> 01:14:03,160
Minħabba 90 huwa integer.

1450
01:14:03,160 --> 01:14:06,820
>> JASON Hirschhorn: Minħabba atoi tieħu
spag u jibdel din in l-eqreb numru sħiħ

1451
01:14:06,820 --> 01:14:08,320
rappreżentanza ta 'dak string.

1452
01:14:08,320 --> 01:14:13,650
Iżda l-sekwenza 90 mhuwiex il-integer
90 jew in-numru 90.

1453
01:14:13,650 --> 01:14:17,920
L-sekwenza 90 firxa ta 'tnejn, jew
tliet karattri, pjuttost, l-9

1454
01:14:17,920 --> 01:14:22,740
karattru, il-karattru 0, u
l-backslash 0 karattru.

1455
01:14:22,740 --> 01:14:26,260
>> U aħna qed miktub atoi minħabba li, għal
eżempju, meta tieħu l-kmand

1456
01:14:26,260 --> 01:14:30,230
argument linja, u huwa salvati
ARGV, huwa ffrankati bħala sekwenza.

1457
01:14:30,230 --> 01:14:32,940
Iżda jekk inti tixtieq li titratta dan bħala numru,
għandek bżonn biex jaqilbu għal

1458
01:14:32,940 --> 01:14:34,700
integer attwali.

1459
01:14:34,700 --> 01:14:37,210
Li għamilna wieħed ta 'settijiet problema tagħna.

1460
01:14:37,210 --> 01:14:38,800
Li għamilna f'numru
ta 'settijiet problema tagħna.

1461
01:14:38,800 --> 01:14:41,690
Kulħadd li ħa integer
bħala argument linja tal-kmand.

1462
01:14:41,690 --> 01:14:46,490
B'tali mod li għalhekk il-funzjoni atoi tagħna
tieħu string.

1463
01:14:46,490 --> 01:14:51,910
>> Għalhekk għal darb'oħra, fl-eżempju tagħna hawn, aħna qed
se tieħu l-aħħar wieħed.

1464
01:14:51,910 --> 01:14:55,050
Aħna ser inaqqas il-karattru
0 minnha, minħabba l-karattri 0

1465
01:14:55,050 --> 01:14:58,810
mnaqqas mill-karattru 0 jagħtik
numru attwali 0, skond

1466
01:14:58,810 --> 01:15:00,950
l-matematika ASCII li nagħmlu.

1467
01:15:00,950 --> 01:15:04,870
>> Minħabba karattri rappreżentati kif
differenti minn attwali tagħhom - il-

1468
01:15:04,870 --> 01:15:08,830
karattru ta ', per eżempju,
lowercase a huwa 97.

1469
01:15:08,830 --> 01:15:10,260
Mhuwiex - oops!

1470
01:15:10,260 --> 01:15:13,290
Mhuwiex kwalunkwe inti tistenna
li tkun, 0, per eżempju.

1471
01:15:13,290 --> 01:15:16,200
Allura inti għandek naqqas il-
karattru li tikseb 0.

1472
01:15:16,200 --> 01:15:18,950
>> Allura aħna qed tmur biex tagħmel dan hawn
li jiksbu n-numru attwali.

1473
01:15:18,950 --> 01:15:22,560
U allura aħna ser immoltiplika lilha mill
qawwa ta '10ħ jiddependi fuq fejn

1474
01:15:22,560 --> 01:15:27,030
hija fis-sekwenza, u mbagħad ħu li
u iżżidhiex mal detentur post tagħna

1475
01:15:27,030 --> 01:15:32,520
varjabbli hekk nistgħu toħroġ bi
integer ġdida finali tagħna.

1476
01:15:32,520 --> 01:15:35,080
Does li jagħmel sens għal kulħadd?

1477
01:15:35,080 --> 01:15:37,730
>> Allura aħna ma tkunx qed tmur għall-kodiċi dan
dritt issa, għaliex aħna qed

1478
01:15:37,730 --> 01:15:38,830
jkollna fuq żmien qasir.

1479
01:15:38,830 --> 01:15:40,860
I ruhna ghall-ħin ta 'dak.

1480
01:15:40,860 --> 01:15:44,620
Imma dan huwa dak, wieħed jittama, inti
ikunu jistgħu jagħmlu fuq il-kwizz - fil-

1481
01:15:44,620 --> 01:15:47,710
ħafna inqas, tikseb dan pseudocode
miktub.

1482
01:15:47,710 --> 01:15:50,840
>> U mbagħad, jekk konna li tikteb il-
pseudocode, fil-fatt, nistgħu nagħmlu dan

1483
01:15:50,840 --> 01:15:51,490
pretty malajr.

1484
01:15:51,490 --> 01:15:55,230
Kull linja ta 'kummenti li aħna kiteb
hawn jittraduċi għal madwar

1485
01:15:55,230 --> 01:15:56,970
linja waħda tal-kodiċi C.

1486
01:15:56,970 --> 01:16:01,780
Tiddikjara varjabbli ġdid, bil-miktub
a loop, xi tnaqqis, uħud

1487
01:16:01,780 --> 01:16:07,070
multiplikazzjoni, u xi assenjazzjoni.

1488
01:16:07,070 --> 01:16:09,020
Aħna'd probabbilment wkoll jridu
jiktbu linja tar-ritorn.

1489
01:16:09,020 --> 01:16:12,040
Aħna tista 'ukoll tixtieq li tqiegħed
xi kontrolli hawn.

1490
01:16:12,040 --> 01:16:12,655
Yeah.

1491
01:16:12,655 --> 01:16:15,720
>> STUDENT: Allura nistgħu jikkura
i bħall-sekwenza attwali?

1492
01:16:15,720 --> 01:16:18,730
Għaliex naf huwa biss l-indirizz.

1493
01:16:18,730 --> 01:16:22,090
Bħal, kif tista 'tikseb it-tul ta'
il string qed jingħadda?

1494
01:16:22,090 --> 01:16:25,310
>> JASON Hirschhorn: Allura kif għamlet
it-tul ta 'string?

1495
01:16:25,310 --> 01:16:25,830
Strlen.

1496
01:16:25,830 --> 01:16:26,660
>> STUDENT: strlen, yeah.

1497
01:16:26,660 --> 01:16:30,550
Iżda int tista 'tpoġġi s bħala l-
argument għal dan?

1498
01:16:30,550 --> 01:16:34,620
>> JASON Hirschhorn: So strlen
jieħu stilla char.

1499
01:16:34,620 --> 01:16:38,090
U jirriżulta li star char, u
iżomm jingħaddu sakemm jiġrilha għal

1500
01:16:38,090 --> 01:16:41,865
backslash 0. strlen kien effettivament
wieħed mill-programmi l-oħra we

1501
01:16:41,865 --> 01:16:42,850
kienu ser kodiċi.

1502
01:16:42,850 --> 01:16:44,560
Din kienet waħda oħra tajba għall-kodiċi.

1503
01:16:44,560 --> 01:16:47,270
Li wieħed daqsxejn aktar faċli, għaliex jekk
int ser biex jaħsbu dwar dak

1504
01:16:47,270 --> 01:16:47,830
kunċettwalment -

1505
01:16:47,830 --> 01:16:51,620
I biss qal out loud - strlen ġej
a pointer u jżomm għaddejjin u

1506
01:16:51,620 --> 01:16:54,210
għadd u issorveljar sakemm
inti tilħaq backslash 0.

1507
01:16:54,210 --> 01:16:56,530
>> STUDENT: OK, ltqajna.

1508
01:16:56,530 --> 01:17:00,200
>> JASON Hirschhorn: Allura aħjar ta '
Xorti fuq kwizz 0 għada.

1509
01:17:00,200 --> 01:17:03,170
Jekk għandek xi mistoqsijiet, I ser
jkun barra wara dan.

1510
01:17:03,170 --> 01:17:05,610
Ħossok liberu li email me.

1511
01:17:05,610 --> 01:17:08,480
Jilħqu lill-TF tiegħek jekk int
mhux fis-sezzjoni tiegħi, jew tikseb tiegħi

1512
01:17:08,480 --> 01:17:10,005
email jekk inti tixtieq dan.

1513
01:17:10,005 --> 01:17:13,140
>> Jekk inti tixtieq li skerz u biss tibgħat
email, email freakout, I ser

1514
01:17:13,140 --> 01:17:16,710
inti tibgħat lura, bħal, wiċċ smiley,
jew, bħal, ċajta jew xi ħaġa.

1515
01:17:16,710 --> 01:17:18,190
Hekk li tħossok liberu li tagħmel dan ukoll.

1516
01:17:18,190 --> 01:17:20,750
Xorti tajba għal darb'oħra, u jien ser
tara inti kollha ġimgħa d-dieħla.

1517
01:17:20,750 --> 01:17:23,435