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[Daqq tal-mużika]

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>> Doug LLOYD: OK so suġġeriment
qabel ma tibda hawn.

5
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Jekk int ma jaraw l-video fuq
Pointers inti tista 'tixtieq li tagħmel dan ewwel.

6
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Minħabba dan il-video huwa ieħor
mod ta 'ħidma ma' indikaturi.

7
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>> Allura li għaddej biex jitkellmu
dwar ċerti kunċetti

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li aħna tkopri fl-
Pointers video, u aħna qed

9
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se tinjora minnhom issa,
jekk wieħed jassumi li dawn qed diġà

10
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tip ta 'mifhuma.

11
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Allura dan huwa biss twissija leali tiegħek
li jekk int tara dan il-video

12
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u inti ma bbenefikawx l-
pointers video, jista tip ta '

13
00:00:27,814 --> 00:00:29,610
fly fuq kap tiegħek ftit.

14
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U għalhekk jista 'jkun aħjar
sabiex isegwu din f'dik l-ordni.

15
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>> Allura aħna diġà raw wieħed
mod biex jaħdmu ma pointers,

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li hija aħna tiddikjara
varjabbli, u allura aħna

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tiddikjara varjabbli ieħor, pointer
varjabbli, li l-punti lilha.

18
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Allura konna ħoloq
varjabbli ma 'isem, konna

19
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ħolqot it-tieni varjabbli ma 'isem,
u aħna punt li t-tieni varjabbli

20
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f'dak ewwel.

21
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Din it-tip ta jkollha
problema għalkemm, minħabba li

22
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twassalna sabiex tkun taf eżattament
kemm memorja kemm aħna qed

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ser jeħtieġu l-mument
programm tagħna hija miġbura.

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>> Għaliex huwa li?

25
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Għaliex aħna jeħtieġu li jkunu kapaċi biex insemmu jew
jidentifikaw il-varjabbli kollha possibbli

26
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nistgħu jiltaqgħu.

27
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Aħna jista 'jkollhom firxa li jista' jkun
kapaċi li jkollhom ħafna ta 'informazzjoni,

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iżda huwa għadu ma
eżattament preċiżi biżżejjed.

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X'jiġri jekk ma nafux,
dak jekk aħna għandna ebda idea

30
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kemm aħna bzonn fil-ħin jikkompilaw?

31
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Jew dak jekk programm tagħna se
run għal żmien twil verament,

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taċċetta utent varji
data, u ma nistgħux verament

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jistma jekk aħna qed
ser jeħtieġu 1,000 unità?

34
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>> Mhuwiex simili nistgħu
jgħidu fil-linja tal-kmand

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jidħol kemm oġġetti
taħseb li għandek bzonn.

36
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Ukoll jekk dak li raden huwa ħażin?

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Allokazzjoni memorja dinamika
tip ta 'jippermetti t-triq

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biex tikseb madwar din il-problema partikolari.

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U l-mod tagħmlu
huwa bl-użu pointers.

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>> Nistgħu nużaw indikaturi għall
jiksbu aċċess għal dinamikament

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memorja allokati, memorja li hija
allokati kif program tiegħek tkun qed taħdem.

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Mhuwiex allokat fil-ħin jikkompilaw.

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Meta inti dinamikament talloka
memorja niġu minn grupp

44
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tal-memorja magħrufa bħala l-borġ.

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Preċedentement il-memorja konna
ilha taħdem magħhom fil-kors

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ġie ġejjin minn grupp
tal-memorja magħrufa bħala l-munzell.

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Mod tajjeb biex ġeneralment
iżomm mind-- u din ir-regola

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mhux dejjem iżżomm veru,
iżda pjuttost ħafna kważi

49
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dejjem istivi true-- huwa li kull
darba li inti tagħti isem varjabbli it

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probabbilment ħajjiet fuq il-munzell.

51
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U kull darba li inti ma
jagħtu varjabbli isem,

52
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li inti tista 'tagħmel bil-memorja dinamika
allokazzjoni, jgħix fuq il-borġ.

53
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>> Issa jien tip ta 'preżentazzjoni ta' din kif
jekk hemm dawn iż-żewġ ġabriet ta 'memorja.

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Iżda int tista raw dan
dijagramma, li hija ġeneralment

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rappreżentazzjoni ta '
dak memorja Dehra,

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u aħna mhux qed tmur għall-kura dwar l
l-għalf fil-quċċata u l-qiegħ.

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What we care about hija din il-parti fil
nofs hawn, borġ u munzell.

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Kif tistgħu taraw mill
tħares lejn dan dijagramma,

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dawn fil-fatt huma mhux tnejn
pools separati ta 'memorja.

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Huwa wieħed ġabra kondiviża ta 'memorja
fejn tibda, f'dan viżwali

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tibda fil-qiegħ
u jibdew mili

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mill-qiegħ bil-munzell, u inti
tibda fil-quċċata u l-bidu mili

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mill-top down bl-borġ.

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Imma dan huwa verament l-
istess pool, huwa biss

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spots differenti, f'postijiet differenti
fil-memorja li qed jiġu allokati.

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U inti tista 'taħdem barra mill-
memorja billi jew li

67
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-borġ jmorru it-triq kollha
mal-qiegħ, jew ikollhom

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il-munzell tmur it-triq lejn il-wiċċ,
jew li l-munzell u l munzell

69
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jiltaqgħu kontra xulxin.

70
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Kollha ta 'dawn jistgħu jkunu kundizzjonijiet
li jikkawżaw program tiegħek

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li jispiċċaw ta 'memorja.

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Sabiex iżommu dan f'moħħhom.

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Meta nitkellmu dwar
-borġ u l munzell

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aħna qed verament jitkellem dwar il-
istess blokki ġenerali tal-memorja, just

75
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porzjonijiet differenti ta 'dak memorja.

76
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>> Allura kif nistgħu tikseb dinamiku
allokati memorja fl-ewwel post?

77
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Kif programm tagħna jiksbu
memorja kif huwa taħdem?

78
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Well C jipprovdi funzjoni msejħa
malloc, allokatur memorja, li

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inti tagħmel sejħa biex, u inti tgħaddi fil
kif bytes ta 'memorja li inti tixtieq ħafna.

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Mela jekk program tiegħek tkun qed taħdem
u inti tixtieq runtime numru sħiħ,

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inti tista mallock erba 'bytes ta'
memorja, malloc parentesi erbgħa.

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>> mallock se jgħaddu
tfittex permezz-borġ,

83
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għaliex aħna qed dinamiku
allokazzjoni memorja,

84
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u se terġa 'lura lilek
a pointer għal dak memorja.

85
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Ma jtik li memory--
ma tagħtiha isem,

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tagħtik pointer lilha.

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U hekk hu għalhekk darb'oħra I said
li huwa importanti li forsi

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jkollhom jaraw il-video pointers
qabel nikbru wisq fis dan.

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Allura malloc għaddej biex
jagħtuk lura pointer.

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>> Jekk mallock ma jista 'jagħtik xi
memorja għaliex inti ħadthom jispiċċaw,

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dan ser jagħtuk lura pointer null.

92
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Do you remember dak li jiġri jekk aħna
ipprova u dereference pointer null?

93
00:04:15,282 --> 00:04:17,019
Aħna jbatu tort seg, right?

94
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Li probabbilment mhux tajba.

95
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>> Allura kull darba li inti tagħmel sejħa
li malloc inti dejjem, dejjem

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bżonn li jiċċekkja jekk il-
pointer huwa ħadt lura huwa null.

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Jekk huwa, inti għandek bżonn biex tintemm program tiegħek
għaliex jekk inti tipprova u dereference

98
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il pointer null int ser
li jbatu tort segmentazzjoni

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u l-programm tiegħek huwa
ser crash xorta waħda.

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Allura kif nistgħu statikament
jiksbu integer?

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>> int x.

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Imxejna probabbilment għamlu dan
mazz ta 'drabi, id-dritt?

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Dan joħloq varjabbli imsejjaħ
x li jgħix fuq il-munzell.

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Kif nistgħu dinamikament jiksbu integer?

105
00:04:46,190 --> 00:04:50,010
Int px star ugwali malloc 4.

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>> Jew b'mod aktar xieraq
aħna'd ngħidu px star int

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ugwali daqs malloc ta 'int,
biss biex titfa 'inqas

108
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numri magic madwar programm tagħna.

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Dan se jinkiseb għalina
erba 'bytes ta' memorja mill-borġ,

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u l-pointer nikbru
lura għall huwa msejjaħ px.

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U mbagħad biss kif konna
isir qabel we

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jista dereference px li
aċċess li l-memorja.

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Kif nikbru integer mill-utent?

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Nistgħu ngħidu int x ugwali tikseb int.

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Li pjuttost sempliċi.

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X'jiġri jekk irridu noħolqu firxa
ta 'x sufruni li jgħixu fuq il-munzell?

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float stack_array-- dak l-isem
tal array-- tagħna parentesi kwadri x.

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Li se toħloq għalina firxa
ta 'x sufruni li jgħixu fuq il-munzell.

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Nistgħu noħolqu firxa ta 'sufruni
li jgħix fuq l-borġ, wisq.

120
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Is-sintassi tista 'tidher a
ftit aktar diffiċli,

121
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iżda nistgħu ngħidu float
heap_array star ugwali

122
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malloc x darbiet id-daqs tal-float.

123
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I bżonn spazju biżżejjed biex iżomm
x f'wiċċ l-ilma valuri tal-punti.

124
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Allura ngħid I bżonn 100
sufruni, jew 1,000 floats.

125
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Allura f'dak il-każ ikun
400 bytes għal 100 sufruni,

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jew 4,000 bytes għal 1,000 sufruni,
għax kull float jieħu

127
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erba 'bytes ta' spazju.

128
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>> Wara li tagħmel dan nista 'nuża l-
sintassi bracket kwadru fuq heap_array.

129
00:06:05,110 --> 00:06:08,970
Just kif nixtieq fuq stack_array, I
tista 'aċċess elementi tagħha individwalment

130
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użu heap_array żero, wieħed heap_array.

131
00:06:11,590 --> 00:06:15,800
Iżda tfakkar r-raġuni nistgħu nagħmlu dan
huwa minħabba l-isem ta 'firxa fis-C

132
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huwa verament pointer li
ewwel element li firxa ta.

133
00:06:19,990 --> 00:06:23,480
Allura l-fatt li aħna qed tkun iddikjarat li
firxa ta 'sufruni fuq il-munzell hawn

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huwa attwalment daqsxejn qarrieqa.

135
00:06:24,810 --> 00:06:27,600
Aħna verament huma fil-
tieni linja tal-kodiċi hemmhekk

136
00:06:27,600 --> 00:06:32,360
ħolqien wkoll pointer għal blokki ta '
memorja li aħna mbagħad jagħmlu xi xogħol magħhom.

137
00:06:32,360 --> 00:06:35,620
>> Hawn il-problema kbira ma
dinamikament allokati memorja għalkemm,

138
00:06:35,620 --> 00:06:38,360
u dan huwa għaliex huwa verament
importanti li jiġu żviluppati xi drawwiet tajba

139
00:06:38,360 --> 00:06:39,800
meta inti qed jaħdmu magħha.

140
00:06:39,800 --> 00:06:43,060
B'differenza statikament iddikjarat
memorja, memorja tiegħek

141
00:06:43,060 --> 00:06:46,790
mhux awtomatikament lura lill-
sistema meta funzjoni tiegħek isir.

142
00:06:46,790 --> 00:06:49,280
Mela jekk ikollna prinċipali, u
prinċipali jitlob funzjoni

143
00:06:49,280 --> 00:06:53,860
f, meta f finituri dak kollu li qed jagħmel
u prospetti kontroll tal-programm

144
00:06:53,860 --> 00:06:58,810
lura għall ewlenija, kollha tal-memorja
li f użati jingħata lura.

145
00:06:58,810 --> 00:07:01,250
Huwa jista 'jerġa' jintuża
minn xi programm ieħor,

146
00:07:01,250 --> 00:07:04,250
jew xi funzjoni oħra li
gets imsejħa aktar tard fil prinċipali.

147
00:07:04,250 --> 00:07:06,970
Hija tista 'tuża l-istess memorja aktar mill-ġdid.

148
00:07:06,970 --> 00:07:09,620
>> Jekk inti dinamikament
jallokaw memorja għalkemm

149
00:07:09,620 --> 00:07:14,380
inti għandek tgħid b'mod espliċitu l-
sistema li qed isir magħha.

150
00:07:14,380 --> 00:07:18,370
Hija ser żżomm fuq dan għalik, li jistgħu
jwassal għal problema ta 'inti taħdem barra

151
00:07:18,370 --> 00:07:19,290
tal-memorja.

152
00:07:19,290 --> 00:07:22,179
U fil-fatt aħna kultant jirreferu
għal dan bħala nixxija memorja.

153
00:07:22,179 --> 00:07:24,970
U xi kultant dawn tnixxijiet memorja
jista 'attwalment jiġi verament devastanti

154
00:07:24,970 --> 00:07:27,020
għall-prestazzjoni tas-sistema.

155
00:07:27,020 --> 00:07:31,120
>> Jekk int utent internet frekwenti
inti tista 'tuża ċerti web browsers,

156
00:07:31,120 --> 00:07:35,630
u jien mhux se isem ismijiet hawn, iżda
hemm xi browsers web hemmhekk

157
00:07:35,630 --> 00:07:39,150
li huma notorji għal fatt li
tnixxijiet memorja li ma jsibux fissi.

158
00:07:39,150 --> 00:07:44,570
U jekk inti tħalli browser tiegħek miftuħa
għal perjodu twil ħafna ta 'żmien, ġranet

159
00:07:44,570 --> 00:07:48,060
u ġranet, jew ġimgħat, inti xi kultant
tista 'tinnota li s-sistema tiegħek

160
00:07:48,060 --> 00:07:49,790
huwa running tassew, tassew bil-mod.

161
00:07:49,790 --> 00:07:54,640
U r-raġuni għal dan hija li
l-browser allokat memorja,

162
00:07:54,640 --> 00:07:57,320
iżda mbagħad ma qal is-sistema
li huwa jsir minnu.

163
00:07:57,320 --> 00:08:01,000
U hekk li l-weraq memorja inqas
disponibbli għal kulħadd ta 'programmi oħra tiegħek

164
00:08:01,000 --> 00:08:04,480
li jkollhom jaqsmu, għax int
leaking-- li web browser

165
00:08:04,480 --> 00:08:06,755
programm qed tqattar memorja.

166
00:08:06,755 --> 00:08:08,880
Kif nistgħu jagħtuk memorja lura
meta aħna qed isir magħha?

167
00:08:08,880 --> 00:08:10,838
Ukoll fortunatament huwa
Mod faċli ħafna biex jagħmlu dan.

168
00:08:10,838 --> 00:08:11,710
Aħna biss ħielsa it.

169
00:08:11,710 --> 00:08:15,020
Hemm funzjoni msejħa ħielsa,
hija taċċetta pointer għall-memorja,

170
00:08:15,020 --> 00:08:16,010
u aħna qed imorru tajjeb.

171
00:08:16,010 --> 00:08:18,310
>> Mela ejja ngħidu aħna qed fil-
nofs tal-programm tagħna,

172
00:08:18,310 --> 00:08:21,970
irridu li malloc 50 karattru.

173
00:08:21,970 --> 00:08:25,710
Aħna rridu li malloc firxa li jistgħu
kapaċi jżomm 50 karattru.

174
00:08:25,710 --> 00:08:29,109
U meta aħna jiksbu pointer lura għall
li, isem li pointer huwa kelma.

175
00:08:29,109 --> 00:08:30,900
We do dak kollu aħna qed
se jagħmlu ma 'kelma,

176
00:08:30,900 --> 00:08:33,440
u mbagħad meta nkunu
isir aħna biss ħielsa it.

177
00:08:33,440 --> 00:08:37,460
U issa għandna lura dawk 50
bytes ta 'memorja lura għas-sistema.

178
00:08:37,460 --> 00:08:40,147
Xi funzjoni oħra jistgħu jużawhom.

179
00:08:40,147 --> 00:08:43,480
Aħna ma jkollhom għalfejn tinkwieta dwar ssofri
nixxija memorja għaliex għandna meħlusa kelma.

180
00:08:43,480 --> 00:08:46,639
Imxejna minħabba l-memorja lura,
hekk aħna qed isir jaħdmu magħha.

181
00:08:46,639 --> 00:08:48,430
Allura hemm tliet
regoli tad-deheb li għandhom

182
00:08:48,430 --> 00:08:51,700
jinżamm fil-moħħ meta int
dinamikament allokazzjoni memorja

183
00:08:51,700 --> 00:08:52,990
ma malloc.

184
00:08:52,990 --> 00:08:56,480
Kull blokk ta 'memorja li
inti malloc għandhom ikunu meħlusa

185
00:08:56,480 --> 00:08:58,430
qabel program tiegħek finituri running.

186
00:08:58,430 --> 00:09:02,029
Issa mill-ġdid, fil-appliance jew fil-
IDE dan it-tip ta 'jiġri għalik xorta

187
00:09:02,029 --> 00:09:04,820
meta you-- dan se jiġri xorta waħda
meta programm tiegħek jiġi tterminat,

188
00:09:04,820 --> 00:09:06,880
l-memorja se jiġu rilaxxati.

189
00:09:06,880 --> 00:09:10,750
Imma hija kodifikazzjoni ġeneralment tajba
prattika li dejjem, meta qed isir,

190
00:09:10,750 --> 00:09:13,810
ħielsa dak li għandek mallocd.

191
00:09:13,810 --> 00:09:16,690
>> Cela dit, uniċi affarijiet li
inti stajt mallocd għandhom jinħelsu.

192
00:09:16,690 --> 00:09:19,880
Jekk inti statikament jiddikjaraw
numru sħiħ, int x semi-colon,

193
00:09:19,880 --> 00:09:23,500
li jgħix fuq l-munzell, inti
ma allura jridux ħielsa x.

194
00:09:23,500 --> 00:09:25,970
Allura uniċi affarijiet li inti stajt
mallocd għandhom jinħelsu.

195
00:09:25,970 --> 00:09:28,960
>> U fl-aħħarnett, ma xi ħaġa b'xejn darbtejn.

196
00:09:28,960 --> 00:09:31,170
Li jistgħu jwasslu għal
sitwazzjoni stramb ieħor.

197
00:09:31,170 --> 00:09:33,530
Allura dak kollu li inti stajt
mallocd għandha jinħelsu.

198
00:09:33,530 --> 00:09:36,000
Affarijiet biss li inti stajt
malloc għandhom jinħelsu.

199
00:09:36,000 --> 00:09:38,730
U ma xi ħaġa b'xejn darbtejn.

200
00:09:38,730 --> 00:09:43,660
>> Mela ejja jmorru permezz ta 'eżempju hawn
ta 'dak li xi dinamiku allokat

201
00:09:43,660 --> 00:09:46,122
memorja jista 'dehra mħallta
ma xi memorja statika.

202
00:09:46,122 --> 00:09:47,080
X'jista 'jiġri hawn?

203
00:09:47,080 --> 00:09:48,913
Ara jekk inti tista 'ssegwi
flimkien u raden x'hemm

204
00:09:48,913 --> 00:09:51,720
se jiġri bħala immorru
permezz ta 'dawn il-linji kollha ta' kodiċi.

205
00:09:51,720 --> 00:09:53,980
>> Allura aħna ngħidu int m.

206
00:09:53,980 --> 00:09:54,840
X'jiġri hawn?

207
00:09:54,840 --> 00:09:56,339
Ukoll dan huwa pjuttost sempliċi.

208
00:09:56,339 --> 00:09:59,650
I joħolqu varjabbli numru sħiħ imsejħa m.

209
00:09:59,650 --> 00:10:01,400
I kulur it aħdar,
għaliex dak l-kulur

210
00:10:01,400 --> 00:10:03,730
li nuża meta jien jitkellem
dwar varjabbli numru sħiħ.

211
00:10:03,730 --> 00:10:05,160
Huwa kaxxa.

212
00:10:05,160 --> 00:10:08,400
Huwa sejjaħ m, u inti tista '
interi maħżen ġewwa ta 'dan.

213
00:10:08,400 --> 00:10:12,400
>> X'jiġri jekk I imbagħad ngħid star int a?

214
00:10:12,400 --> 00:10:13,530
Ukoll li pjuttost simili.

215
00:10:13,530 --> 00:10:15,780
Jien ħolqien kaxxa msejħa a.

216
00:10:15,780 --> 00:10:19,100
Huwa kapaċi li int azjenda
stilla, pointers għal interi.

217
00:10:19,100 --> 00:10:21,570
Hekk jien kulur it aħdar ish ukoll.

218
00:10:21,570 --> 00:10:24,140
>> Naf li xi ħaġa
li tagħmel ma 'numru sħiħ,

219
00:10:24,140 --> 00:10:25,852
iżda mhux nnifisha numru sħiħ.

220
00:10:25,852 --> 00:10:27,310
Imma hija pjuttost l-istess idea.

221
00:10:27,310 --> 00:10:28,101
Stajt ħolqot kaxxa.

222
00:10:28,101 --> 00:10:30,070
Kemm minn dawn id-dritt
issa jgħixu fuq il-munzell.

223
00:10:30,070 --> 00:10:32,520
Stajt tawhom kemm l-ismijiet.

224
00:10:32,520 --> 00:10:36,750
>> star int b ugwali daqs malloc ta 'int.

225
00:10:36,750 --> 00:10:38,560
Dan wieħed jista 'jkun ftit delikata.

226
00:10:38,560 --> 00:10:44,110
Tieħu t-tieni u jaħsbu dwar dak li
tistenna li jiġri fuq dan dijagramma.

227
00:10:44,110 --> 00:10:50,210
star int b ugwali daqs malloc ta 'int.

228
00:10:50,210 --> 00:10:51,940
>> Ukoll dan ma biss toħloq kaxxa waħda.

229
00:10:51,940 --> 00:10:53,800
Dan fil-fatt joħloq żewġ kaxxi.

230
00:10:53,800 --> 00:10:58,670
U hija torbot, huwa jistabbilixxi wkoll
punt fl-relazzjoni.

231
00:10:58,670 --> 00:11:02,240
Imxejna allokat blokka waħda
tal-memorja fuq il-borġ.

232
00:11:02,240 --> 00:11:05,940
Avviż li l-kaxxa lemin ta 'fuq
hemm ma jkollux isem.

233
00:11:05,940 --> 00:11:06,760
>> Aħna mallocd dan.

234
00:11:06,760 --> 00:11:08,050
Hija teżisti fis-borġ.

235
00:11:08,050 --> 00:11:10,090
Iżda b għandha isem.

236
00:11:10,090 --> 00:11:11,950
Huwa varjabbli pointer imsejjaħ b.

237
00:11:11,950 --> 00:11:13,910
Li jgħix fuq il-munzell.

238
00:11:13,910 --> 00:11:18,250
>> Allura huwa biċċa ta 'memorja
li l-punti ma 'xulxin.

239
00:11:18,250 --> 00:11:21,840
b fih l-indirizz
ta 'dik blokk ta' memorja.

240
00:11:21,840 --> 00:11:23,757
Huwa ma jkollu l-isem mod ieħor.

241
00:11:23,757 --> 00:11:24,590
Iżda dan jindika lilha.

242
00:11:24,590 --> 00:11:29,760
Allura meta ngħidu star int b ugwali
daqs malloc ta 'int, li hemm dritt,

243
00:11:29,760 --> 00:11:33,490
li vleġġa li feġġ fuq l-
lemin hemm, li ħaġa sħiħa,

244
00:11:33,490 --> 00:11:36,740
I ser ikollhom jidher
għal darb'oħra, huwa dak li jiġri.

245
00:11:36,740 --> 00:11:39,341
Kollha ta 'li jiġri fil
li linja waħda tal-kodiċi.

246
00:11:39,341 --> 00:11:41,340
Issa aħna ser tingħata ftit aktar
sempliċi mill-ġdid.

247
00:11:41,340 --> 00:11:43,330
a ugwali ampersand m.

248
00:11:43,330 --> 00:11:46,280
Tiftakar dak
ugwali ampersand m hu?

249
00:11:46,280 --> 00:11:48,920
Ukoll li l-gets indirizz m ta.

250
00:11:48,920 --> 00:11:54,150
Jew imqiegħda aktar permezz tad-dijagramma,
punti li m.

251
00:11:54,150 --> 00:11:56,360
>> a ugwali b.

252
00:11:56,360 --> 00:11:57,560
OK hekk hawn xulxin.

253
00:11:57,560 --> 00:11:59,230
A ugwali b.

254
00:11:59,230 --> 00:12:02,260
X'hemm jiġri
għall-dijagramma dan iż-żmien?

255
00:12:02,260 --> 00:12:04,330
>> Ukoll ifakkar li l-
xogħlijiet operatur assenjazzjoni

256
00:12:04,330 --> 00:12:08,960
billi jassenja l-valur fis-
dritt għall-valur fuq ix-xellug.

257
00:12:08,960 --> 00:12:14,820
Allura minflok ta 'tipponta lejn m, a issa
jindika l-istess post li l-punti b.

258
00:12:14,820 --> 00:12:18,900
a ma jwassalx biex b, a
jinnota punti fejn b.

259
00:12:18,900 --> 00:12:25,280
>> Jekk osservat li b li
kienu ugwali ampersand b.

260
00:12:25,280 --> 00:12:28,150
Iżda minflok ugwali b biss
ifisser li aub huma issa

261
00:12:28,150 --> 00:12:31,770
tipponta lejn l-istess indirizz, minħabba
ġewwa tal b huwa biss l-indirizz.

262
00:12:31,770 --> 00:12:35,004
U issa ġewwa ta 'l-istess indirizz.

263
00:12:35,004 --> 00:12:37,170
m ugwali għal 10, probabbilment l-
aktar ħaġa sempliċi

264
00:12:37,170 --> 00:12:38,690
aħna ghamilt fil ftit.

265
00:12:38,690 --> 00:12:40,460
Poġġi l-10 fil-kaxxa.

266
00:12:40,460 --> 00:12:45,640
Star b ugwali m flimkien ma '2, jitlob lura mingħandhom
pointers vidjo tagħna dak star b jfisser.

267
00:12:45,640 --> 00:12:50,230
Aħna qed tmur biex dereference bu mressqa
xi valur f'dak il-lok memorja.

268
00:12:50,230 --> 00:12:51,860
F'dan il-każ 12.

269
00:12:51,860 --> 00:12:55,300
>> Allura meta aħna dereference punt ta '
ifakkar aħna biss ivvjaġġar l-vleġġa.

270
00:12:55,300 --> 00:12:58,205
Jew fi kliem ieħor, aħna
tmur f'dak indirizz memorja

271
00:12:58,205 --> 00:12:59,580
u aħna jimmanipulaw dan b'xi mod.

272
00:12:59,580 --> 00:13:00,830
Npoġġux xi valur fil hemmhekk.

273
00:13:00,830 --> 00:13:03,960
F'dan il-każ star b
ugwali m plus 2 huwa biss

274
00:13:03,960 --> 00:13:08,230
mur l-varjabbli indikat mill b,
mur l-memorja indikat mill b,

275
00:13:08,230 --> 00:13:11,750
u mqiegħda m plus 2 fil hemm, 12.

276
00:13:11,750 --> 00:13:14,970
>> Issa I mingħajr b.

277
00:13:14,970 --> 00:13:16,490
X'jiġri meta I mingħajr b?

278
00:13:16,490 --> 00:13:18,800
Ftakar dak li għidt mezzi ħielsa.

279
00:13:18,800 --> 00:13:21,920
What am I qal meta I mingħajr b?

280
00:13:21,920 --> 00:13:23,410
>> Jien jsir taħdem ma 'dan, id-dritt?

281
00:13:23,410 --> 00:13:25,702
I essenzjalment tagħti l-memorja.

282
00:13:25,702 --> 00:13:26,910
I jagħtu lura għas-sistema.

283
00:13:26,910 --> 00:13:33,010
I m'għandhomx bżonn dan aktar huwa
dak li jien tgħidilhom, OK?

284
00:13:33,010 --> 00:13:37,390
>> Issa jekk ngħid star a
huwa daqs 11 inti tista 'probabbilment

285
00:13:37,390 --> 00:13:40,460
diġà tgħid li xi ħaġa ħażina
jiġri hawn, id-dritt?

286
00:13:40,460 --> 00:13:44,160
U fil-fatt jekk I ppruvaw li I probabbilment
jsofrux tort segmentazzjoni.

287
00:13:44,160 --> 00:13:47,140
Għaliex issa, għalkemm
qabel dik blokki ta 'memorja

288
00:13:47,140 --> 00:13:50,220
kienet xi ħaġa li kelli
aċċess għal, f'dan il-punt

289
00:13:50,220 --> 00:13:54,590
jien issa jaċċessaw memorja li
mhuwiex legali biex nagħmel l-aċċess.

290
00:13:54,590 --> 00:13:57,330
>> U kif aħna se probabbilment
ifakkar, meta aħna jkollhom aċċess memorja

291
00:13:57,330 --> 00:14:00,000
li aħna mhux qed suppost għal mess,
dak l-aktar kawża komuni

292
00:14:00,000 --> 00:14:01,860
ta 'segmentazzjoni
tort. U hekk program tiegħi

293
00:14:01,860 --> 00:14:05,170
kieku crash jekk I ppruvaw jagħmlu dan.

294
00:14:05,170 --> 00:14:09,910
Għalhekk għal darb'oħra din hija idea tajba li tikseb tajba
prattika u tajba drawwiet sodi

295
00:14:09,910 --> 00:14:12,920
meta jaħdmu ma malloc u ħielsa,
sabiex inti ma jbatux segmentazzjoni

296
00:14:12,920 --> 00:14:15,310
ħsarat, u li tuża
dinamikament allokat tiegħek

297
00:14:15,310 --> 00:14:17,370
memorja responsabbli.

298
00:14:17,370 --> 00:14:20,300
>> Jien Doug Lloyd dan huwa CS50.

299
00:14:20,300 --> 00:14:21,947