1
00:00:00,000 --> 00:00:00,980

2
00:00:00,980 --> 00:00:04,410
>> [Daqq ta mużika]

3
00:00:04,410 --> 00:00:11,147

4
00:00:11,147 --> 00:00:12,230
DAVID J. Malan: Kull dritt.

5
00:00:12,230 --> 00:00:16,440
Dan huwa CS50, u dan
hija t-tmiem tal-Ġimgħa 2.

6
00:00:16,440 --> 00:00:18,480
Allura llum, aħna qed tmur
li tkompli ħarsa tagħna

7
00:00:18,480 --> 00:00:21,150
lejn kif aħna nirrappreżentaw affarijiet
taħtha l-hood-- qegħdin nitbiegħdu

8
00:00:21,150 --> 00:00:23,520
minn numri bħall interi
u floating valuri tal-punti

9
00:00:23,520 --> 00:00:26,810
u jiffoka fuq kordi u
programmi fl-aħħarnett aktar interessanti.

10
00:00:26,810 --> 00:00:30,140
Iżda aħna ser ukoll tagħti ħarsa lejn
Koppja ta 'problems-- speċifiċi għall-domain

11
00:00:30,140 --> 00:00:33,620
l-ewwel wieħed minnhom se
jkun jinvolvi kriptografija,

12
00:00:33,620 --> 00:00:36,570
l-arti ta 'scrambling informazzjoni,
fejn inti ara hawn fuq hawn

13
00:00:36,570 --> 00:00:41,480
hija stampa ta 'Radio Orfni Annie
ċirku decoder sigriet mill-imgħoddi.

14
00:00:41,480 --> 00:00:46,490
>> Dan huwa attwalment forma ħafna primitive
u l-forma favur it-tfal ta 'cryptopgraphy

15
00:00:46,490 --> 00:00:50,590
li biha dan iċ-ċirku għandu żewġ disks--
ġewwa wieħed u barra wieħed.

16
00:00:50,590 --> 00:00:54,740
U billi ddawwar wieħed minn dawk, inti tista '
essenzjalment linja up ittri bħal A

17
00:00:54,740 --> 00:00:59,520
permezz Z ma 'ittri oħra
bħal B permezz A. Fi kliem ieħor,

18
00:00:59,520 --> 00:01:03,730
inti tista litteralment dawwar l-alfabett,
b'hekk ġejjin bi immappjar minn

19
00:01:03,730 --> 00:01:07,820
ittri lill ittri b'tali mod li, jekk inti
riedu li jibgħat messaġġ sigriet

20
00:01:07,820 --> 00:01:11,820
li xi ħadd bħal Annie, inti tista 'tikteb
isfel messaġġ tiegħek u mbagħad dawwar

21
00:01:11,820 --> 00:01:15,370
l-ittri, li biha, jekk inti tfisser
li jgħidu "A," inti minflok jgħidu "B,"

22
00:01:15,370 --> 00:01:17,280
inti jfissirx li jgħidu "B,"
inti minflok jgħidu "C" -

23
00:01:17,280 --> 00:01:20,240
jew xi ħaġa ftit aktar għaqlija
minn that-- u mbagħad, finalment,

24
00:01:20,240 --> 00:01:24,630
sakemm Annie għandha dan decoder
ring, hi tista jiddekowdja-messaġġ.

25
00:01:24,630 --> 00:01:28,540
Issa, inti tista 'tfakkar, fil-fatt, li din il-
kien użat fil-film famuż ħafna li

26
00:01:28,540 --> 00:01:31,140
jilgħab ad nauseum matul
l-istaġun tal-Milied.

27
00:01:31,140 --> 00:01:32,650
Ejja tagħti ħarsa hawn.

28
00:01:32,650 --> 00:01:35,294

29
00:01:35,294 --> 00:01:37,210
RALPHIE PARKER: "Be hija
magħrufa kollha fil-qosor

30
00:01:37,210 --> 00:01:41,000
li Ralph Parker huwa b'dan maħtur
membru ta 'Little Orfni Annie Secret

31
00:01:41,000 --> 00:01:44,860
Ċirku u huwa intitolat li l-
unuri u l-benefiċċji li jseħħu għalihom. "

32
00:01:44,860 --> 00:01:47,410
>> RALPHIE PARKER (narrating):
Iffirmat Little Orfni Annie.

33
00:01:47,410 --> 00:01:50,070
Kontrofirmata, Pierre Andre!

34
00:01:50,070 --> 00:01:51,490
Fl-linka.

35
00:01:51,490 --> 00:01:55,494
Honors u l-benefiċċji,
diġà fl-età ta 'disa.

36
00:01:55,494 --> 00:01:57,402
>> [Daqq ta mużika]

37
00:01:57,402 --> 00:02:00,470
>> [Chatter RADIO]

38
00:02:00,470 --> 00:02:01,470
RALPHIE PARKER: Come fuq.

39
00:02:01,470 --> 00:02:02,344
Ejja nikseb fuq magħha.

40
00:02:02,344 --> 00:02:06,029
I m'għandhomx bżonn dak kollu li jazz
dwar kuntrabandisti u pirati.

41
00:02:06,029 --> 00:02:08,820
Announcer RADJU: Isma għada
lejl għall-avventura jikkonkludi

42
00:02:08,820 --> 00:02:11,060
ta 'L-pirata Vapur Iswed.

43
00:02:11,060 --> 00:02:14,740
Issa, wasal iż-żmien għal tal Annie
Messaġġ Secret għalik membri

44
00:02:14,740 --> 00:02:17,110
tal-Ċirku Sigriet.

45
00:02:17,110 --> 00:02:20,700
Ftakar gidjien, biss il-membri
ta Secret Circle Annie

46
00:02:20,700 --> 00:02:23,270
jistgħu jiddekowdja-messaġġ sigriet Annie.

47
00:02:23,270 --> 00:02:27,270
>> Ftakar, Annie jiddependi fuq int.

48
00:02:27,270 --> 00:02:30,060
Set labar tiegħek lil B-2.

49
00:02:30,060 --> 00:02:34,004
Hawn hu l-message-- 12, 11, 2--

50
00:02:34,004 --> 00:02:36,503
RALPHIE PARKER (narrating): I
am fl-ewwel laqgħa sigrieta tiegħi.

51
00:02:36,503 --> 00:02:40,041
Announcer RADJU: --25, 14, 11, 18, 16--

52
00:02:40,041 --> 00:02:42,790
RALPHIE PARKER (narrating): Oh,
Pierre kien fil tonight vuċi kbira.

53
00:02:42,790 --> 00:02:46,110
I tista 'tgħid li dak il-tonight
messaġġ kien verament importanti.

54
00:02:46,110 --> 00:02:47,930
>> Announcer RADJU: --3, 25.

55
00:02:47,930 --> 00:02:49,940
C'est messaġġ mill Annie ruħha.

56
00:02:49,940 --> 00:02:52,182
Ftakar, ma tgħid xi ħadd.

57
00:02:52,182 --> 00:02:55,077
>> [Panting]

58
00:02:55,077 --> 00:02:57,285
RALPHIE PARKER (narrating):
Disgħin sekondi wara, jien

59
00:02:57,285 --> 00:03:00,090
fil-kamra biss fil-
dar fejn tifel ta 'disa'

60
00:03:00,090 --> 00:03:04,380
jista ipoġġu fil-privatezza u jiddekowdja.

61
00:03:04,380 --> 00:03:04,990
Ah.

62
00:03:04,990 --> 00:03:05,680
"B."

63
00:03:05,680 --> 00:03:06,524
>> [Chuckles]

64
00:03:06,524 --> 00:03:08,684
>> RALPHIE PARKER (narrating):
I marru għall-ieħor.

65
00:03:08,684 --> 00:03:09,610
"E."

66
00:03:09,610 --> 00:03:11,641
L-ewwel kelma hija "jkun."

67
00:03:11,641 --> 00:03:12,140
Iva!

68
00:03:12,140 --> 00:03:14,293
Hija kien ġejjin faċli issa.

69
00:03:14,293 --> 00:03:15,259
"U."

70
00:03:15,259 --> 00:03:16,225
>> [Chuckles]

71
00:03:16,225 --> 00:03:18,157
>> Randy PARKER: Aw, come fuq, Ralphie.

72
00:03:18,157 --> 00:03:19,606
I gotta go!

73
00:03:19,606 --> 00:03:21,538
>> RALPHIE PARKER: I ser tkun dritt isfel, Ma.

74
00:03:21,538 --> 00:03:22,504
Whiz GEE.

75
00:03:22,504 --> 00:03:25,402

76
00:03:25,402 --> 00:03:31,220
"T." "O." "Kun żgur
għal. "" Kun żgur li "dak?

77
00:03:31,220 --> 00:03:33,981
Liema kienet Little Orphan Annie
nipprova ngħid? "Kun żgur li" dak?

78
00:03:33,981 --> 00:03:35,522
OMM: Ralphie, Randy s'est li jmorru.

79
00:03:35,522 --> 00:03:36,735
Gaat jekk jogħġbok toħroġ?

80
00:03:36,735 --> 00:03:38,190
>> RALPHIE PARKER: Kull dritt, omm!

81
00:03:38,190 --> 00:03:39,787
I ser tkun out dritt!

82
00:03:39,787 --> 00:03:41,995
RALPHIE PARKER (narrating):
I kien jkollna aktar mill-qrib issa.

83
00:03:41,995 --> 00:03:43,370
It-tensjoni kien terribbli.

84
00:03:43,370 --> 00:03:44,794
Liema kienet?

85
00:03:44,794 --> 00:03:47,656
Il-destin tal-pjaneta
jista hang fil-bilanċ.

86
00:03:47,656 --> 00:03:50,518
>> OMM: Ralphie, li Randy ltqajna biex tmur!

87
00:03:50,518 --> 00:03:53,635
>> RALPHIE PARKER: I ser tkun dritt
out, għall biki out loud!

88
00:03:53,635 --> 00:03:55,343
RALPHIE PARKER
(Narrating): Kważi hemm!

89
00:03:55,343 --> 00:03:56,520
Swaba tiegħi taru!

90
00:03:56,520 --> 00:03:58,500
Mind tiegħi kien nassa azzar.

91
00:03:58,500 --> 00:03:59,850
Kull pori ivvibrat.

92
00:03:59,850 --> 00:04:01,806
Kien kważi ċar!

93
00:04:01,806 --> 00:04:02,773
Iva!

94
00:04:02,773 --> 00:04:03,273
Iva!

95
00:04:03,273 --> 00:04:03,773
Iva!

96
00:04:03,773 --> 00:04:04,740
Iva!

97
00:04:04,740 --> 00:04:10,250
>> RALPHIE PARKER: "Kun żgur
li tixrob Ovaltine tiegħek. "

98
00:04:10,250 --> 00:04:10,750
Ovaltine?

99
00:04:10,750 --> 00:04:14,864

100
00:04:14,864 --> 00:04:17,539
A kummerċjali crummy?

101
00:04:17,539 --> 00:04:19,439
>> [Daqq ta mużika]

102
00:04:19,439 --> 00:04:21,724
>> RALPHIE PARKER: Iben ta 'kelba.

103
00:04:21,724 --> 00:04:23,460
>> [Laughing]

104
00:04:23,460 --> 00:04:27,070
>> DAVID J. Malan: Allura dan allura huwa
glimpse lejn dak kriptografija

105
00:04:27,070 --> 00:04:29,880
jista 'jkun għal this-- a
tixrob minn imgħoddi.

106
00:04:29,880 --> 00:04:30,900
Allura tħabbira malajr.

107
00:04:30,900 --> 00:04:33,410
Jekk inti liberu dan
Ġimgħa fl 1:15 u kieku

108
00:04:33,410 --> 00:04:36,610
simili li jingħaqdu magħna għal CS50
lunch, ras għal dan il-URL hawn.

109
00:04:36,610 --> 00:04:38,080
Ewwel li jidħlu, l-ewwel iservu bħas-soltu.

110
00:04:38,080 --> 00:04:41,840
Iżda maż-żmien, aħna ser tagħmel żgur li
aktar kulmin tixtieq tipparteċipa

111
00:04:41,840 --> 00:04:43,640
tista 'tfassal skeda għaqli.

112
00:04:43,640 --> 00:04:45,170
>> Allura kordi.

113
00:04:45,170 --> 00:04:47,940
Għandna Zamyla-- min
inti issa stajt sodisfatti bl-aktar probabbli

114
00:04:47,940 --> 00:04:50,750
fil Problema Set 1-- li
isem huwa spelt b'hekk.

115
00:04:50,750 --> 00:04:53,570
U ejja ngħidu li inti ittajpjat isem tagħha
fi programm tal-kompjuter li l-

116
00:04:53,570 --> 00:04:55,710
jużaw xi ħaġa bħal getString.

117
00:04:55,710 --> 00:04:57,890
Sabiex tkun irkuprata
dawk keystrokes, kif

118
00:04:57,890 --> 00:05:01,620
do we go dwar jirrappreżentaw
string, kelma, paragrafu,

119
00:05:01,620 --> 00:05:03,960
jew ittri multipli bħal dawn hawn?

120
00:05:03,960 --> 00:05:06,790
>> Aħna tkellimna aħħar darba dwar
interi u problemi

121
00:05:06,790 --> 00:05:09,960
li jinqalgħu bl overflow numru sħiħ
u floating valuri tal-punti

122
00:05:09,960 --> 00:05:12,190
u problemi li
jinqalgħu fi ħdan preċiżjoni.

123
00:05:12,190 --> 00:05:16,080
Bil kordi, aħna mill-inqas
għandhom ftit aktar flessibilità

124
00:05:16,080 --> 00:05:17,970
minħabba strings-- biss
fil-world-- reali

125
00:05:17,970 --> 00:05:19,790
jista 'jkun ta' tul pretty arbitrarja.

126
00:05:19,790 --> 00:05:21,055
Pretty qasir, pretty twil.

127
00:05:21,055 --> 00:05:23,680
Iżda anke dakinhar, aħna qed tmur biex
issib li l-kompjuters tista 'xi kultant

128
00:05:23,680 --> 00:05:27,200
jispiċċaw tal-memorja u lanqas
taħżen string kbir biżżejjed.

129
00:05:27,200 --> 00:05:30,840
>> Iżda għal issa, ejja tibda Ħares
string bħala xi ħaġa fil dawn il-kaxxi

130
00:05:30,840 --> 00:05:31,340
hawn.

131
00:05:31,340 --> 00:05:36,410
Allura sitt kaxxi bħal dawn, li kull waħda minnhom
jirrappreżenta karattru jew "char."

132
00:05:36,410 --> 00:05:40,646
Allura tfakkar li "char" - c-h-a-r-- huwa
wieħed mit-tipi ta 'dejta mibnija fil fil C.

133
00:05:40,646 --> 00:05:43,520
U x'hemm sbieħ hija li inti tista 'tuża
dik it-tip ta bħala blokk bini,

134
00:05:43,520 --> 00:05:47,880
biċċa puzzle, jekk inti se, biex jiffurmaw
tip akbar ta 'data li aħna ser tkompli

135
00:05:47,880 --> 00:05:49,410
li jsejjaħ "string."

136
00:05:49,410 --> 00:05:53,650
>> Issa, x'hemm utli dwar il-ħsieb
dwar affarijiet simili kordi b'dan il-mod?

137
00:05:53,650 --> 00:05:57,720
Ukoll, jirriżulta li nistgħu
attwalment lieva din l-istruttura

138
00:05:57,720 --> 00:06:01,420
li attwalment aċċess karattri individwali
b'mod pjuttost sempliċi.

139
00:06:01,420 --> 00:06:04,099
Jien ser jimxi 'l quddiem u joħolqu
fajl imsejjaħ "stringzero.c,"

140
00:06:04,099 --> 00:06:05,765
imma int tista 'sejħa hija tkun xi tkun tixtieq.

141
00:06:05,765 --> 00:06:08,500
U fuq il-websajt tal-kors hija
diġà dan l-eżempju bil-quddiem,

142
00:06:08,500 --> 00:06:10,430
sabiex inti m'għandekx bżonn li
tip kollox barra.

143
00:06:10,430 --> 00:06:13,820
>> U jien se jmorru 'l quddiem
u l-ewwel tagħmel bla effett prinċipali int.

144
00:06:13,820 --> 00:06:15,980
U fi ftit jiem,
aħna ser tibda tease apparti

145
00:06:15,980 --> 00:06:19,070
dak null hija hawnhekk, għaliex huwa
int li jmiss għal main, u ibqa 'sejjer hekk.

146
00:06:19,070 --> 00:06:21,180
Iżda għal issa, ejja tkompli
li kopja paste dan.

147
00:06:21,180 --> 00:06:23,455
>> Jien ser tiddikjara string imsejjaħ i.

148
00:06:23,455 --> 00:06:26,920
U jien ser jirritornaw minn
GetString x'ikun it-tipi utent fil.

149
00:06:26,920 --> 00:06:29,170
Dan se jkun sempliċi
programm, l-ebda struzzjonijiet,

150
00:06:29,170 --> 00:06:31,336
Jien biss ser bl-addoċċ
jistennew li l-utent ikun jaf

151
00:06:31,336 --> 00:06:32,600
x'għandhom jagħmlu biex jżommha sempliċi.

152
00:06:32,600 --> 00:06:34,220
>> U issa jien se jkollhom għall-loop.

153
00:06:34,220 --> 00:06:37,450
U ġewwa tal għat loop tiegħi jien
ser ikollhom int i gets żero.

154
00:06:37,450 --> 00:06:40,660
U i huwa, għal darb'oħra, biss konvenzjoni,
varjabbli indiċi għall-għadd,

155
00:06:40,660 --> 00:06:42,350
imma I tista 'sejħa dan ikun x'ikun nixtieq.

156
00:06:42,350 --> 00:06:46,275
Jien ser tagħmel i huwa inqas than-- tajjeb
Isem Zamyla huwa sitt ittri twil.

157
00:06:46,275 --> 00:06:48,150
So I m ser hard
kodiċi li hemm għal issa.

158
00:06:48,150 --> 00:06:49,730
>> U mbagħad I ++.

159
00:06:49,730 --> 00:06:53,190
U issa ġewwa minn dawn kaboċċi
braces Jien ser tagħmel printf,

160
00:06:53,190 --> 00:06:55,460
u nixtieq li jistampaw wieħed
karattru fi żmien.

161
00:06:55,460 --> 00:06:58,227
So jien ser tuża% C għal
forsi l-ewwel darba.

162
00:06:58,227 --> 00:07:00,560
U mbagħad I tixtieq li jistampaw kull
karattru fuq linja tagħha stess.

163
00:07:00,560 --> 00:07:02,550
So jien ser tpoġġi
ftit backslash n hemmhekk.

164
00:07:02,550 --> 00:07:03,640
Kwotazzjoni Agħlaq.

165
00:07:03,640 --> 00:07:06,250
>> U issa I trid tagħmel xi ħaġa hawn.

166
00:07:06,250 --> 00:07:10,610
Irrid li jistampa l-
ittra speċifika fis-sekwenza,

167
00:07:10,610 --> 00:07:13,670
i, kif jien mtennija
minn żero fuq sa sitta.

168
00:07:13,670 --> 00:07:17,150
Fi kliem ieħor, I jridu
jistampaw il-karattru i'th ta s.

169
00:07:17,150 --> 00:07:18,420
Issa kif nista 'nagħmel dan?

170
00:07:18,420 --> 00:07:21,550
>> Ukoll ħafna bħall-kaxxi fil
din ir-rappreżentanza hawn,

171
00:07:21,550 --> 00:07:25,560
tip ta ', conjure l-kunċett ta' boxing
ittri, inti tista 'bl-istess mod tagħmel dan

172
00:07:25,560 --> 00:07:32,630
sintattikament fis-C billi sempliċiment jispeċifikaw,
Irrid li jistampa l i i'th karattru.

173
00:07:32,630 --> 00:07:35,640
Jużaw il-parentesi kwadri
fuq it-tastiera tal-kompjuter tiegħek

174
00:07:35,640 --> 00:07:38,910
li fuq tastiera Istati Uniti huma
ġeneralment iktar ċavetta ritorn tiegħek.

175
00:07:38,910 --> 00:07:42,630
>> Allura dan huwa pjuttost mhux dritt
għadhom, kif inti jista 'jkollok ndunat.

176
00:07:42,630 --> 00:07:44,780
Imma jien ser tip ta '
addoċċ nimxu 'l quddiem hawnhekk.

177
00:07:44,780 --> 00:07:47,020
U jien ser tagħmel jagħmlu string 0.

178
00:07:47,020 --> 00:07:50,860
Iżda qabel I tagħmel dan, ejja ara jekk irridu
ma tistax tantiċipa xi żbalji komuni.

179
00:07:50,860 --> 00:07:52,844
Huwa dan se jikkompilaw?

180
00:07:52,844 --> 00:07:54,510
Le, jien nieqsa mazz sħiħ ta 'affarijiet.

181
00:07:54,510 --> 00:07:55,280
Libreriji I smajt.

182
00:07:55,280 --> 00:07:58,480
>> Allura li header files
tista I tixtieq iżżid hawnhekk?

183
00:07:58,480 --> 00:07:59,205
Yeah.

184
00:07:59,205 --> 00:08:01,580
>> UDJENZA: Għandek bżonn
I standard / O [inaudible]

185
00:08:01,580 --> 00:08:02,663
>> DAVID J. Malan: Eċċellenti.

186
00:08:02,663 --> 00:08:06,060
So I bżonn standard I / O. Għal dak li
iskop do Irrid I standard / O?

187
00:08:06,060 --> 00:08:06,670
Għal printf.

188
00:08:06,670 --> 00:08:09,220
Allura jinkludu stdio.h.

189
00:08:09,220 --> 00:08:13,490
U inti wkoll tipproponi li I jinkludu
il-librerija CS50 għal liema raġuni?

190
00:08:13,490 --> 00:08:14,650
Biex ikollhom kordi.

191
00:08:14,650 --> 00:08:17,780
Allura aħna ser tara dak
Librerija CS50 hija tagħmel

192
00:08:17,780 --> 00:08:19,260
biex joħolqu dan il-kunċett ta 'sekwenza.

193
00:08:19,260 --> 00:08:21,930
Iżda għal issa, inti tista 'biss jaħsbu
li bħala tip ta 'data attwali.

194
00:08:21,930 --> 00:08:23,596
>> Allura li jidher li jkun ftit mnaddfa.

195
00:08:23,596 --> 00:08:27,060
U issa jien se jimxi 'l quddiem
u tabilħaqq ma jagħmlu string 0.

196
00:08:27,060 --> 00:08:27,700
Ikkumpilat.

197
00:08:27,700 --> 00:08:28,370
Allura li tajjeb.

198
00:08:28,370 --> 00:08:32,799
So ./string0 let me zoom fl sabiex inkunu nistgħu
tara aktar mill-qrib x'inhu jiġri.

199
00:08:32,799 --> 00:08:33,850
Ikteb.

200
00:08:33,850 --> 00:08:37,789
Z-A-M-Y-L-A jidħol.

201
00:08:37,789 --> 00:08:39,440
U konna stampata isem Zamyla tal.

202
00:08:39,440 --> 00:08:40,409
>> Allura dak pjuttost tajba.

203
00:08:40,409 --> 00:08:43,220
Allura issa ejja imorru quddiem u
run dan il-programm mill-ġdid,

204
00:08:43,220 --> 00:08:45,659
u t-tip out isem sħiħ Daven tal.

205
00:08:45,659 --> 00:08:46,450
Surprise, sorpriża.

206
00:08:46,450 --> 00:08:48,021
Ikteb.

207
00:08:48,021 --> 00:08:48,520
Hmm.

208
00:08:48,520 --> 00:08:51,750
Aħna ma stampat tal Daven
ewwel isem sħiħ korrett.

209
00:08:51,750 --> 00:08:54,250
Issa dan għandu jkun ovvju fil
retrospettivament minħabba dak,

210
00:08:54,250 --> 00:08:57,010
tip ta ', id-deċiżjoni disinn stupid?

211
00:08:57,010 --> 00:08:59,590
>> Yeah, I iebsa kodifikati l-
sitta ġewwa ta tiegħi għal loop.

212
00:08:59,590 --> 00:09:01,610
Issa I did li biss minħabba
Kont naf isem Zamyla tal

213
00:09:01,610 --> 00:09:02,776
kienet se tkun sitt ittri.

214
00:09:02,776 --> 00:09:04,720
Iżda żgur dan mhuwiex
soluzzjoni ġenerali.

215
00:09:04,720 --> 00:09:07,720
Għalhekk jirriżulta li nistgħu dinamikament
insemmu l-tul ta 'sekwenza

216
00:09:07,720 --> 00:09:10,440
billi ssejjaħ il-funzjoni msejħa strlen.

217
00:09:10,440 --> 00:09:12,840
>> Għal darb'oħra, deliberatament
konċiż jismu biss

218
00:09:12,840 --> 00:09:14,450
li jagħmilha aktar konvenjenti għat-tip.

219
00:09:14,450 --> 00:09:17,170
Imma dak li sinonimu ma '
jkollna l-tul ta 'sekwenza.

220
00:09:17,170 --> 00:09:23,190
Jien se jmorru lura fis terminal tiegħi
tieqa u jerġa 'tmexxi l-kumpilatur.

221
00:09:23,190 --> 00:09:24,170
Iżda huwa yelling fil lili.

222
00:09:24,170 --> 00:09:29,130
Impliċitament li tiddikjara funzjoni librerija
strlen ma tip mhux iffirmat int const--

223
00:09:29,130 --> 00:09:29,780
Jien mitlufa.

224
00:09:29,780 --> 00:09:30,590
Kompletament.

225
00:09:30,590 --> 00:09:32,940
>> Allura, speċjalment fir tiegħek
għajnejn tibda glaze fuq

226
00:09:32,940 --> 00:09:36,000
ma messaġġi ta 'żball bħal dan, fokus
onestament fuq l-ewwel ftit kliem.

227
00:09:36,000 --> 00:09:38,590
Nafu l-problema hija fil-
linja 8, kif indikat hawn.

228
00:09:38,590 --> 00:09:40,500
U huwa fil string-0.c.

229
00:09:40,500 --> 00:09:43,580
Impliċitament li tiddikjara
funzjoni librerija strlen.

230
00:09:43,580 --> 00:09:47,000
Allura li huwa ġeneralment ser
jkun mudell ta 'messaġġi ta' żball.

231
00:09:47,000 --> 00:09:49,190
Impliċitament tiddikjara xi ħaġa.

232
00:09:49,190 --> 00:09:53,250
>> Għalhekk fil-qosor, dak li jiena deher li
għamlu fir-rigward għal-linja 8, hawnhekk.

233
00:09:53,250 --> 00:09:56,880
Liema jista 'jkun is-soluzzjoni jkun saħansitra
jekk inti stajt qatt jintużaw strlen yourself?

234
00:09:56,880 --> 00:09:58,907
>> UDJENZA: Parti ta 'librerija differenti?

235
00:09:58,907 --> 00:10:00,740
DAVID J. Malan: Parti
ta 'librerija differenti.

236
00:10:00,740 --> 00:10:02,400
Għalhekk huwa ddikjarat, biex ngħidu hekk.

237
00:10:02,400 --> 00:10:07,510
Huwa msemmi fl xi fajl
għajr stdio.h u CS50.h.

238
00:10:07,510 --> 00:10:09,179
Issa fejn m'huwa ddefinit?

239
00:10:09,179 --> 00:10:12,220
Biex inkun onest, inti jew għandek biss
jafu dan off-quċċata tar-ras tiegħek,

240
00:10:12,220 --> 00:10:13,640
jew inti Google dan u nsib.

241
00:10:13,640 --> 00:10:18,150
Jew jafu dan, stajt fetħet fil-CS50
appliance-programm terminal, li

242
00:10:18,150 --> 00:10:22,200
huwa biss il-big, screen full verżjoni ta '
x'hemm fil-qiegħ ta 'tieqa gedit tal.

243
00:10:22,200 --> 00:10:24,970
>> U jirriżulta li hemm
kmand bl-istess mod konċiż, imsejħa

244
00:10:24,970 --> 00:10:29,280
bniedem għall-manwali, fejn jekk inti tip
l-isem ta 'funzjoni u hit Ikteb,

245
00:10:29,280 --> 00:10:32,240
int ser tingħata lura pjuttost
dokumentazzjoni arcane.

246
00:10:32,240 --> 00:10:35,299
Huwa biss it-test li ġeneralment
jistenna ftit xi ħaġa bħal din.

247
00:10:35,299 --> 00:10:37,090
Huwa ftit kbira
ewwel daqqa t'għajn.

248
00:10:37,090 --> 00:10:39,048
Imma franchement jien ser
let għajnejn tiegħi glaze fuq

249
00:10:39,048 --> 00:10:41,930
u jiffoka biss fuq il-parti
I kura dwar għall-mument.

250
00:10:41,930 --> 00:10:42,780
>> Liema huwa dan.

251
00:10:42,780 --> 00:10:45,470
Liema jistenna strutturalment simili
xi ħaġa jien familjari magħhom.

252
00:10:45,470 --> 00:10:48,080
Tabilħaqq il-paġna bniedem, hekk
biex jitkellmu, se jgħidlek

253
00:10:48,080 --> 00:10:51,590
fil dak header fajl funzjoni
bħal strlen huwa definit.

254
00:10:51,590 --> 00:10:54,170
So jien se jmorru lura issa biex gedit.

255
00:10:54,170 --> 00:10:59,070
U jien ser jimxi 'l quddiem u
żid fil hawn # Jinkludu

256
00:10:59,070 --> 00:11:00,480
u tiffranka l-fajl.

257
00:11:00,480 --> 00:11:04,300
>> Jien ser ċar l-iskrin ma
Kontroll L Jekk inti ħadthom ġiet mintix.

258
00:11:04,300 --> 00:11:08,210
U jien ser make mill-ġdid run
string.0, jikkompila dan iż-żmien.

259
00:11:08,210 --> 00:11:11,790
./string.0 Zamyla.

260
00:11:11,790 --> 00:11:15,020
Dan deher li jaħdmu Let me go
quddiem u terġa 'ssir bl Davenport.

261
00:11:15,020 --> 00:11:15,860
Ikteb.

262
00:11:15,860 --> 00:11:17,730
U li, wisq, deher li jaħdmu.

263
00:11:17,730 --> 00:11:21,220
>> Allura nistgħu nagħmlu ftit aħjar minn dan,
għalkemm, nistgħu tibda affarijiet puliti

264
00:11:21,220 --> 00:11:23,257
up biss ftit.

265
00:11:23,257 --> 00:11:25,590
U jien ser fil-fatt
jintroduċu ħaġa waħda oħra issa.

266
00:11:25,590 --> 00:11:28,930
Jien ser jimxi 'l quddiem u
Ħlief dan fil-fajl differenti.

267
00:11:28,930 --> 00:11:31,770
U jien ser sejħa
dan il-fajl string1.c biss

268
00:11:31,770 --> 00:11:34,620
li tkun konsistenti mal-kodiċi
inti ser tkun tista 'ssib online.

269
00:11:34,620 --> 00:11:37,050
>> U ejja tiffoka fuq
eżattament l-istess kodiċi.

270
00:11:37,050 --> 00:11:39,000
Jirriżulta li stajt
Kien tip ta 'teħid

271
00:11:39,000 --> 00:11:42,600
għall mogħtija l-fatt li laptop tiegħi,
u min-naħa, l-appliance CS50

272
00:11:42,600 --> 00:11:47,450
għandha ħafna ta 'memorja, lott ta'
RAM, lott ta 'bytes ta' spazju

273
00:11:47,450 --> 00:11:48,920
li nista jista 'jaħżen kordi.

274
00:11:48,920 --> 00:11:53,560
>> Iżda r-realtà jekk I ittajpjat twil
biżżejjed, u biżżejjed keystrokes,

275
00:11:53,560 --> 00:11:56,170
I tista 'fil-tip teorija
fl karattri aktar

276
00:11:56,170 --> 00:11:58,830
minn kompjuter tiegħi
fiżikament memorja għal.

277
00:11:58,830 --> 00:11:59,830
U dan huwa problematiku.

278
00:11:59,830 --> 00:12:03,050
Ferm simili int tista 'biss
għadd tant għoli, fit-teorija,

279
00:12:03,050 --> 00:12:06,600
inti tista 'biss CRAM tant karattri
fis RAM kompjuter tiegħek jew Random

280
00:12:06,600 --> 00:12:07,920
Aċċess Memorja.

281
00:12:07,920 --> 00:12:11,140
>> So I kien aħjar jantiċipaw
din il-problema, anke

282
00:12:11,140 --> 00:12:13,660
għalkemm jista 'jkun rari
każ kantuniera, biex ngħidu hekk.

283
00:12:13,660 --> 00:12:15,670
Ma jiġri li spiss, jista 'jiġri.

284
00:12:15,670 --> 00:12:18,815
U jekk dan jiġri u I ma
tantiċipa u l-programm għal dan,

285
00:12:18,815 --> 00:12:20,300
programm tiegħi tista 'tagħmel li jaf dak.

286
00:12:20,300 --> 00:12:22,220
Jiffriżaw, hang, reboot, ikun x'ikun.

287
00:12:22,220 --> 00:12:24,490
Xi ħaġa antiċipat jista 'jiġri.

288
00:12:24,490 --> 00:12:27,120
>> Allura dak li jien ser tagħmel
issa, issa verament,

289
00:12:27,120 --> 00:12:31,630
huwa qabel I qatt addoċċ
jużaw varjabbli bħall-s dik

290
00:12:31,630 --> 00:12:36,790
ġiet assenjata l-valur tar-ritorn ta '
xi funzjoni oħra bħall getstring,

291
00:12:36,790 --> 00:12:40,200
Jien ser tagħmel żgur
li l-valur tagħha huwa validu.

292
00:12:40,200 --> 00:12:44,280
So I biss jafu minn wara li taqra
Dokumentazzjoni CS50 għall getstring,

293
00:12:44,280 --> 00:12:49,020
li finalment aħna ser punt inti fil,
li getstring prospetti simbolu speċjali

294
00:12:49,020 --> 00:12:53,610
imsejħa NULL, N-U-L-L fil kollha
tappijiet, jekk xi ħaġa tmur ħażin.

295
00:12:53,610 --> 00:12:55,650
>> Allura normalment, dan jirritorna string.

296
00:12:55,650 --> 00:12:59,700
Iżda inkella jekk dan jirritorna N-U-L-L--
aħna ser eventwalment tara dak li verament

297
00:12:59,700 --> 00:13:01,790
means-- li biss mezzi
xi ħaġa ħażina ġara.

298
00:13:01,790 --> 00:13:05,560
Issa dan ifisser, ferm simili fl Scratch,
I jista 'jivverifika kundizzjoni hawn fis-C,

299
00:13:05,560 --> 00:13:08,830
jekk i ma NULL ugwali.

300
00:13:08,830 --> 00:13:11,930
Mela jekk inti stajt ma bbenefikawx dan qabel,
dan ifisser biss ma ugwali.

301
00:13:11,930 --> 00:13:15,290
>> Allura huwa l-oppost ta '
ugwali ugwali, li, Recall,

302
00:13:15,290 --> 00:13:18,940
hija differenti minn wieħed
ugwali, li hija assenjazzjoni.

303
00:13:18,940 --> 00:13:23,030
Mela jekk i ma ugwali
NULL, biss allura do

304
00:13:23,030 --> 00:13:25,980
Irrid li tesegwixxi dawn il-linji ta 'kodiċi.

305
00:13:25,980 --> 00:13:28,080
Allura fi kliem ieħor,
qabel I adsa bl-addoċċ

306
00:13:28,080 --> 00:13:30,919
u tibda mtennija
fuq i, u trattat

307
00:13:30,919 --> 00:13:33,710
bħallikieku hija sekwenza ta '
karattri, jien ser ewwel jiċċekkjaw,

308
00:13:33,710 --> 00:13:37,900
stenna minuta, hija s definittivament mhux
daqs dan il-valur speċjali, NULL?

309
00:13:37,900 --> 00:13:40,030
>> Għaliex jekk huwa, affarijiet ħżiena jista 'jiġri.

310
00:13:40,030 --> 00:13:43,080
U għal issa, jassumi affarijiet li ħżiena
jiġri tfisser crashes programm tiegħek,

311
00:13:43,080 --> 00:13:45,070
u inti ma tistax neċessarjament jirkupraw.

312
00:13:45,070 --> 00:13:46,800
Allura franchement, jidher uglier.

313
00:13:46,800 --> 00:13:48,660
Huwa tip ta 'konfużjoni issa li t'għajn lejn.

314
00:13:48,660 --> 00:13:50,780
Iżda dan se jsir aktar
familjari qabel twil.

315
00:13:50,780 --> 00:13:52,920
>> Imma jien ser tipproponi
issa titjib ieħor.

316
00:13:52,920 --> 00:13:54,660
C'est titjib għall-korrettezza.

317
00:13:54,660 --> 00:13:58,800
Programm My issa huwa aktar korrett, għaliex
fil-każ rari li l-memorja mhux biżżejjed

318
00:13:58,800 --> 00:14:01,180
teżisti, I se jimmaniġġjaw dan,
u jien ser biss tagħmel xejn.

319
00:14:01,180 --> 00:14:02,680
I-inqas mhux se tiġrifa.

320
00:14:02,680 --> 00:14:05,000
>> Imma ejja do verżjoni finali hawn.

321
00:14:05,000 --> 00:14:07,690
U fajl imsejjaħ string2.c.

322
00:14:07,690 --> 00:14:10,190
Jien ser paste li
istess kodiċi għall ftit mument,

323
00:14:10,190 --> 00:14:14,210
u jien ser tenfasizza dan
linja, 11, hawn, għal ftit mument.

324
00:14:14,210 --> 00:14:18,179
Issa r-realtà hija li l-kompilaturi intelliġenti
bħal Clang tista 'tiffissa dan għalina

325
00:14:18,179 --> 00:14:19,970
wara l-kwinti
mingħajr tagħna qatt ma jkunu jafu.

326
00:14:19,970 --> 00:14:24,670
Imma ejja jaħsbu dwar dan
fundamentalment bħala disinn problematika.

327
00:14:24,670 --> 00:14:29,010
>> Din il-linja tal-kodiċi huwa, ovvjament,
qal, initialize xi varjabbli i għal 0.

328
00:14:29,010 --> 00:14:30,260
C'est pjuttost sempliċi.

329
00:14:30,260 --> 00:14:34,691
U dak darb'oħra huwa dan
dikjarazzjoni, hawn, i ++, tagħmel?

330
00:14:34,691 --> 00:14:37,066
Imxejna dehru qabel, iżda aħna
ma verament jitkellmu dwar dan.

331
00:14:37,066 --> 00:14:37,900
>> UDJENZA: inkrementazzjoni i.

332
00:14:37,900 --> 00:14:39,191
>> DAVID J. Malan: i inkrementazzjoni.

333
00:14:39,191 --> 00:14:41,890
Allura fuq kull iterazzjoni permezz
dan loop, kull ċiklu,

334
00:14:41,890 --> 00:14:43,570
int inkrementazzjoni i minn wieħed.

335
00:14:43,570 --> 00:14:45,740
Allura jiġrilha akbar, u akbar, u
akbar sakemm il-loop itemm.

336
00:14:45,740 --> 00:14:46,810
Kif ma jtemm?

337
00:14:46,810 --> 00:14:49,430
Ukoll hemm dan nofs
kundizzjoni li aħna ħadthom użati qabel.

338
00:14:49,430 --> 00:14:52,500
You stajt tidher u
walkthroughs fil-P sett.

339
00:14:52,500 --> 00:14:53,880
>> Imma dak li huwa dan qal?

340
00:14:53,880 --> 00:14:58,352
Jagħmlu l-segwenti loop hekk
Sakemm i huwa inqas minn dak?

341
00:14:58,352 --> 00:14:59,810
UDJENZA: It-tul tas-sekwenza.

342
00:14:59,810 --> 00:15:01,518
DAVID J. Malan: Il-
tul tas-sekwenza.

343
00:15:01,518 --> 00:15:04,300
Għalhekk jittraduċi pretty nadif
għall-Ingliż f'dan is-sens.

344
00:15:04,300 --> 00:15:08,810
Issa l-problema hija li kull darba I
jtenni permezz ta 'dan loop fit-teorija,

345
00:15:08,810 --> 00:15:10,000
Jien tistaqsi din il-kwistjoni.

346
00:15:10,000 --> 00:15:12,250
Huwa i inqas mit-tul sensiela ta 'i?

347
00:15:12,250 --> 00:15:14,500
Huwa i inqas mit-tul sensiela ta 'i?

348
00:15:14,500 --> 00:15:18,380
>> Issa qed i jinbidlu fuq kull iterazzjoni?

349
00:15:18,380 --> 00:15:18,880
Huwa.

350
00:15:18,880 --> 00:15:19,629
Minħabba l-++.

351
00:15:19,629 --> 00:15:21,700
Allura kull iterazzjoni i huwa jkollna akbar.

352
00:15:21,700 --> 00:15:25,411
Iżda huwa s jkollna akbar, jew
iżgħar, jew li qed jinbidlu fil-livelli kollha?

353
00:15:25,411 --> 00:15:25,910
No

354
00:15:25,910 --> 00:15:30,240
Allura f'termini ta 'disinn, wieħed mill-assi
flimkien li aħna tipprova tevalwa kodiċi

355
00:15:30,240 --> 00:15:32,610
fil-klassi, dan iħoss tip ta 'stupid.

356
00:15:32,610 --> 00:15:34,690
>> Bħalek huma litteralment,
fuq kull iterazzjoni

357
00:15:34,690 --> 00:15:37,110
ta 'dan loop titlob lill-
istess kwistjoni kkritikat mill-ġdid,

358
00:15:37,110 --> 00:15:40,770
u għal darb'oħra, u għal darb'oħra, u litteralment
huwa qatt se jibdlu.

359
00:15:40,770 --> 00:15:44,220
Mill-inqas jekk jien ma jmissu iu
jippruvaw jibdlu l-kontenut ta 'i.

360
00:15:44,220 --> 00:15:46,610
So I tista 'tagħmel ftit aħjar minn dan.

361
00:15:46,610 --> 00:15:49,530
>> U dak li jien ser tagħmel hu li ma jkunx
tiddikjara wieħed biss varjabbli i,

362
00:15:49,530 --> 00:15:53,330
iżda t-tieni varjabbli I ser arbitrarju,
iżda konvenzjonalment, sejħa hija n.

363
00:15:53,330 --> 00:15:55,940
Jassenja n ugwali għall-
tul sensiela ta 's.

364
00:15:55,940 --> 00:15:59,090
U mbagħad minn hawn, jien ser
tagħmel ottimizzazzjoni ftit għaqlija, hekk

365
00:15:59,090 --> 00:16:03,460
biex jitkellmu, li fl-aħħar tal-ġurnata
huwa aktar korrett jew inqas korrett

366
00:16:03,460 --> 00:16:04,260
minn qabel.

367
00:16:04,260 --> 00:16:05,500
Iżda huwa disinn aħjar.

368
00:16:05,500 --> 00:16:09,480
Fil-fatt li jien jużaw
inqas ħin, inqas ċikli CPU, hekk

369
00:16:09,480 --> 00:16:14,040
biex jitkellmu, li jwieġbu l-istess
kwistjoni, iżda biss ladarba.

370
00:16:14,040 --> 00:16:17,870
>> Kwalunkwe mistoqsijiet dwar dak ġenerali
prinċipju tat-titjib,

371
00:16:17,870 --> 00:16:21,294
jgħidu, l-effiċjenza ta 'programm?

372
00:16:21,294 --> 00:16:21,991
Yeah?

373
00:16:21,991 --> 00:16:23,699
UDJENZA: Għaliex għandek
uża l-[inaudible]?

374
00:16:23,699 --> 00:16:25,760

375
00:16:25,760 --> 00:16:27,010
DAVID J. Malan: Tajba kwistjoni.

376
00:16:27,010 --> 00:16:30,690
Allura għaliex do we tpoġġi l-++ fuq it-tmiem ta '
i minflok il-bidu tal-i?

377
00:16:30,690 --> 00:16:33,070
F'dan il-każ, hija għandha
ebda impatt funzjonali.

378
00:16:33,070 --> 00:16:36,670
U b'mod ġenerali, I-tendenza li
jużaw l-operatur postfix

379
00:16:36,670 --> 00:16:41,750
b'tali mod li huwa ftit aktar ċara bħala
li meta l-operazzjoni qed jiġri.

380
00:16:41,750 --> 00:16:46,670
>> Għal dawk familjari, hemm ieħor
dikjarazzjonijiet li biha inti tista 'tagħmel ++ i.

381
00:16:46,670 --> 00:16:48,747
Dawn huma funzjonalment
ekwivalenti f'dan il-każ

382
00:16:48,747 --> 00:16:51,080
għaliex hemm xejn
madwar dik incrementation.

383
00:16:51,080 --> 00:16:54,435
Iżda int tista 'toħroġ bi
każijiet u linji ta 'kodiċi

384
00:16:54,435 --> 00:16:55,810
li fihom li jagħmel differenza.

385
00:16:55,810 --> 00:16:57,810
Allura ġeneralment, aħna ma
anki jitkellmu dwar dan wieħed.

386
00:16:57,810 --> 00:17:00,690
Minħabba franchement, jagħmel tiegħek
kodiċi sexier, u tip ta 'slicker,

387
00:17:00,690 --> 00:17:01,776
u inqas karattri.

388
00:17:01,776 --> 00:17:04,859
Iżda r-realtà hija li huwa ħafna aktar diffiċli,
I think, anke għalija biex nagħlaq f'moħħi

389
00:17:04,859 --> 00:17:07,319
madwaru kultant,
l-ordni ta 'operazzjonijiet.

390
00:17:07,319 --> 00:17:09,750
Allura bħala twarrib, jekk inti
verament ma bħal din,

391
00:17:09,750 --> 00:17:14,650
anke jekk din hija tip ta 'sexy
tfittex, inti tista 'ukoll tagħmel i + = 1,

392
00:17:14,650 --> 00:17:18,880
li hija l-verżjoni uglier tal-
istess idea għal incrementation postfix.

393
00:17:18,880 --> 00:17:22,250
>> Jien ngħid dan u int
għandhom jagħmlu gost ta 'dan,

394
00:17:22,250 --> 00:17:25,140
iżda inti se jidħlu biex tara kodiċi kif
xi ħaġa sabiħa qabel twil.

395
00:17:25,140 --> 00:17:27,160
>> [Rires]

396
00:17:27,160 --> 00:17:28,410
>> DAVID J. Malan: Right?

397
00:17:28,410 --> 00:17:29,360
Yeah.

398
00:17:29,360 --> 00:17:30,480
Mistoqsija fin-nofs.

399
00:17:30,480 --> 00:17:32,146
>> UDJENZA: Għandek bżonn li jgħidu int n?

400
00:17:32,146 --> 00:17:34,020
DAVID J. Malan: You do
m'għandhomx bżonn li jgħidu int n.

401
00:17:34,020 --> 00:17:37,670
Allura għaliex aħna diġà qal int,
inti m'għandekx bżonn li ngħid mill-ġdid.

402
00:17:37,670 --> 00:17:41,820
Il-qabda hija li n għandu
jkun l-istess tip ta 'data kif i.

403
00:17:41,820 --> 00:17:43,310
Allura li jinsab biss konvenjenza hawn.

404
00:17:43,310 --> 00:17:44,058
Yeah.

405
00:17:44,058 --> 00:17:47,806
>> UDJENZA: Tista jmorru fuq il-
karattru print s bracket i mill-ġdid?

406
00:17:47,806 --> 00:17:48,930
DAVID J. Malan: Assolutament.

407
00:17:48,930 --> 00:17:52,110
Allura% c, recall mill-aħħar
time, huwa biss placeholder.

408
00:17:52,110 --> 00:17:53,930
Dan ifisser tpoġġi char hawn.

409
00:17:53,930 --> 00:17:56,780
backslash n, naturalment, biss
mezzi tpoġġi pawża linja hawn.

410
00:17:56,780 --> 00:17:59,540
Hekk li biss tħalli, issa,
din il-biċċa ta 'sintassi ġdida.

411
00:17:59,540 --> 00:18:03,730
U dan huwa litteralment qal, grab
l-string imsejjaħ iu mur jiksbu tagħha

412
00:18:03,730 --> 00:18:06,050
karattru i'th, biex ngħidu hekk.

413
00:18:06,050 --> 00:18:10,590
>> And I iżommu qal karattru i'th
għax fuq kull iterazzjoni ta 'dan loop

414
00:18:10,590 --> 00:18:14,540
huwa bħallikieku aħna qed istampar
out, l-ewwel parentesi s 0,

415
00:18:14,540 --> 00:18:15,780
bħala programmer jista 'jgħid.

416
00:18:15,780 --> 00:18:18,680
Imbagħad i bracket 1, allura s
bracket 2, allura 3, imbagħad 4.

417
00:18:18,680 --> 00:18:21,610
Iżda naturalment huwa varjabbli,
so I biss jesprimu bl i.

418
00:18:21,610 --> 00:18:23,900
>> Key, għalkemm, hi li tirrealizza,
speċjalment jekk inti stajt ma

419
00:18:23,900 --> 00:18:26,358
ġew acclimating għal din id-dinja
ta 'programmazzjoni, fejn aħna kollha

420
00:18:26,358 --> 00:18:28,950
jidhru li jgħoddu minn żero, gotta
jibdew jingħaddu minn żero issa.

421
00:18:28,950 --> 00:18:35,130
Minħabba kordi, l-ewwel karattru, l-
z fl Zamyla huwa għall-aħjar jew għall-agħar

422
00:18:35,130 --> 00:18:40,490
tmur tgħix fil-numru lokazzjoni żero.

423
00:18:40,490 --> 00:18:48,210
>> Kull dritt, so let me iġġib
us lura hawn biex Zamyla

424
00:18:48,210 --> 00:18:50,746
u ara x'inhu verament għaddej
fuq taħt il-barnuża.

425
00:18:50,746 --> 00:18:52,370
Allura hemm dan il-kunċett ta 'ikkastjar tip.

426
00:18:52,370 --> 00:18:53,800
Inti jista 'jkollok attwalment
lagħbu dan diġà,

427
00:18:53,800 --> 00:18:55,970
forsi għall-Hacker
edizzjoni ta 'P sett wieħed.

428
00:18:55,970 --> 00:19:00,320
Iżda ikkastjar tip biss tirreferi għall-
ħila fis-C u f'xi lingwi oħrajn

429
00:19:00,320 --> 00:19:03,170
li jikkonvertu tip ta 'data wieħed għall-ieħor.

430
00:19:03,170 --> 00:19:05,450
>> Issa kif tista naraw dan
pretty jinftiehem?

431
00:19:05,450 --> 00:19:08,530
Allura dan, recall, huwa l-bidu
tal-alfabett Ingliż.

432
00:19:08,530 --> 00:19:11,265
U l-kuntest, ifakkar, minn
bħal ġimgħa ilu huwa ASCII.

433
00:19:11,265 --> 00:19:13,790
Il-Kodiċi American Standard
għall-Informazzjoni Interchange.

434
00:19:13,790 --> 00:19:17,080
Liema huwa biss mod verament twila
ta 'tgħid immappjar mill-ittri

435
00:19:17,080 --> 00:19:19,370
għal numri, u minn numri għall-ittri.

436
00:19:19,370 --> 00:19:22,940
>> Allura A permezz M hawn, dot dot
dot, linji up ma ', irtirar,

437
00:19:22,940 --> 00:19:25,582
in-numru deċimali 65 fuq up.

438
00:19:25,582 --> 00:19:27,290
U aħna ma nitkellmu
dwar dan b'mod espliċitu,

439
00:19:27,290 --> 00:19:29,850
imma żgur hemm simili
Numri għall-ittri lowercase.

440
00:19:29,850 --> 00:19:30,820
U fil-fatt, hemm.

441
00:19:30,820 --> 00:19:33,730
Id-dinja iddeċieda xi snin
ilu li ftit a, zghar a,

442
00:19:33,730 --> 00:19:35,020
se tkun 97.

443
00:19:35,020 --> 00:19:38,010
U ftit b huwa għaddej
li tkun 98, u ibqa 'sejjer hekk.

444
00:19:38,010 --> 00:19:40,200
>> U għal kwalunkwe ewlenin oħra fuq
tastiera tiegħek, hemm

445
00:19:40,200 --> 00:19:42,190
ser tkun mudell simili ta 'bits.

446
00:19:42,190 --> 00:19:44,540
Jew ekwivalenti, numru deċimali.

447
00:19:44,540 --> 00:19:47,110
Għalhekk il-kwistjoni fil-idejn,
allura, huwa kif nistgħu

448
00:19:47,110 --> 00:19:49,400
attwalment tara dan minn taħt il-barnuża?

449
00:19:49,400 --> 00:19:51,539
So jien se jmorru fuq biex gedit mill-ġdid.

450
00:19:51,539 --> 00:19:53,330
U minflok tip
dan wieħed mill-bidunett,

451
00:19:53,330 --> 00:19:55,330
Jien ser jimxi 'l quddiem u
biss tiftaħ up xi ħaġa

452
00:19:55,330 --> 00:19:58,350
mill-kodiċi tal-lum sejjaħ ASCII żero.

453
00:19:58,350 --> 00:20:01,210
>> U ASCII żero tidher bħal dan.

454
00:20:01,210 --> 00:20:02,710
Mela ejja wrap imħuħ tagħna madwar dan.

455
00:20:02,710 --> 00:20:04,969
Allura l-ewwel, stajt kkummentaw
il-kodiċi, li huwa sabiħ.

456
00:20:04,969 --> 00:20:07,010
Għaliex dan huwa litteralment
javżak me dak li tistenna,

457
00:20:07,010 --> 00:20:08,950
juru mapping għall-ittri uppercase.

458
00:20:08,950 --> 00:20:13,690
Issa I do not pjuttost taf liema I
tfisser li, hekk ejja jiddeduċu.

459
00:20:13,690 --> 00:20:16,870
>> Bl-Ingliż, forsi
kemmxejn techie Ingliż,

460
00:20:16,870 --> 00:20:20,660
dak ma linja 18 jidhru
li tkun qiegħda tagħmel għalina?

461
00:20:20,660 --> 00:20:21,500
Just linja 18.

462
00:20:21,500 --> 00:20:22,430
X'hemm dan jinduċu?

463
00:20:22,430 --> 00:20:25,192
X'hemm Huwa ser kick off hawn?

464
00:20:25,192 --> 00:20:26,100
>> UDJENZA: A loop.

465
00:20:26,100 --> 00:20:26,630
>> DAVID J. Malan: A loop.

466
00:20:26,630 --> 00:20:28,463
U kif ħafna drabi huwa
li ser jtenni?

467
00:20:28,463 --> 00:20:31,562

468
00:20:31,562 --> 00:20:33,270
UDJENZA: [INTERPOSING VOICES]
sitt darbiet.

469
00:20:33,270 --> 00:20:34,830
DAVID J. Malan: Mhux sitt darbiet.

470
00:20:34,830 --> 00:20:35,840
UDJENZA: 26 darba.

471
00:20:35,840 --> 00:20:36,560
DAVID J. Malan: 26 darba.

472
00:20:36,560 --> 00:20:37,060
Yeah, sorry.

473
00:20:37,060 --> 00:20:37,960
26 darba.

474
00:20:37,960 --> 00:20:38,460
Għaliex?

475
00:20:38,460 --> 00:20:41,590
Ukoll, huwa ftit stramb, imma
Stajt beda meta tgħodd minn 65.

476
00:20:41,590 --> 00:20:43,300
Liema hija stramb, iżda mhux ħażin.

477
00:20:43,300 --> 00:20:44,610
Huwa mhux ħażin kull jiġifieri.

478
00:20:44,610 --> 00:20:46,980
U jien tagħmel dan biss
minħabba li, għal dan l-eżempju,

479
00:20:46,980 --> 00:20:50,455
Jien tip ta 'antiċipazzjoni
dak il-kapital A kien 65.

480
00:20:50,455 --> 00:20:53,330
Issa dan mhuwiex l-aktar eleganti
mod biex isir dan, it-tip ta 'kodiċi hard

481
00:20:53,330 --> 00:20:56,130
Valuri esoteric li l-ebda wieħed
huwa qatt mistennija li tiftakar.

482
00:20:56,130 --> 00:21:00,155
>> Iżda għal issa, avviż li jien
tagħmel dan up permezz 65 plus 26.

483
00:21:00,155 --> 00:21:03,030
Minħabba apparentement I ma saħansitra jridu
biex jagħmlu l-aritmetika in my head.

484
00:21:03,030 --> 00:21:04,440
So I ser let l-kumpilatur tagħmel dan.

485
00:21:04,440 --> 00:21:08,600
Iżda mbagħad fuq kull linja, kull iterazzjoni
tal-linja, jien inkrementazzjoni i.

486
00:21:08,600 --> 00:21:10,196
>> Allura issa dan jistenna ftit cryptic.

487
00:21:10,196 --> 00:21:13,320
Iżda aħna għandu jkollhom il-bini bażika
blokki li biex jifhmu dan.

488
00:21:13,320 --> 00:21:15,510
% C huwa biss placeholder għal char.

489
00:21:15,510 --> 00:21:19,010
% I huwa placeholder għal int.

490
00:21:19,010 --> 00:21:23,310
U jirriżulta li bl-użu din
sintassi ġdida, dan parenthetical, hekk

491
00:21:23,310 --> 00:21:26,100
biex jitkellmu, so a tip ta 'dejta
ġewwa parentesi,

492
00:21:26,100 --> 00:21:32,270
I tista 'seħħ l-kumpilatur biex jikkura
i ma huwa integer, iżda bħala char.

493
00:21:32,270 --> 00:21:35,520
>> U b'hekk juru lili il-karattru
ekwivalenti ta 'dak in-numru.

494
00:21:35,520 --> 00:21:37,986
Issa stabbiliti hawn, dan il-kodiċi
huwa pretty ħafna identiċi.

495
00:21:37,986 --> 00:21:39,860
I biss riedu jagħmlu
super espliċitu l-fatt

496
00:21:39,860 --> 00:21:42,095
li jien jibdew fil 97,
li huwa zghar a.

497
00:21:42,095 --> 00:21:44,080
Fuq sa permezz 26 ittri aktar.

498
00:21:44,080 --> 00:21:46,970
U jien doing-- darb'oħra,
ikkastjar i, biex ngħidu hekk.

499
00:21:46,970 --> 00:21:49,160
Jew Tip I ikkastjar, biex ngħidu hekk.

500
00:21:49,160 --> 00:21:51,420
>> Minn int għal char.

501
00:21:51,420 --> 00:21:55,760
Allura l-riżultat aħħari se tkun,
franchement, informazzjoni aħna diġà jafu.

502
00:21:55,760 --> 00:21:59,411
Jien ser jagħmlu
-ascii 0 ma dot-- dot c.

503
00:21:59,411 --> 00:22:02,160
Avviż, inti probabilment għamlet din
żball bħala I biss għamlet aċċidentalment.

504
00:22:02,160 --> 00:22:03,820
Make-ascii 0.

505
00:22:03,820 --> 00:22:06,090
Issa jien ser tagħmel ./ascii-0.

506
00:22:06,090 --> 00:22:09,050
I ser zoom fi, u sfortunatament
li għaddej biex tiskrollja barra l-iskrin.

507
00:22:09,050 --> 00:22:15,060
Iżda aħna naraw chart kollu fejn
a mapep sa 97, mapep B sa 98,

508
00:22:15,060 --> 00:22:18,931
u jekk aħna iscroll aktar
A, naturalment, mapep sa 65.

509
00:22:18,931 --> 00:22:21,180
Allura dan huwa biss biex jgħidu li
dak li aħna kont qed jippriedka,

510
00:22:21,180 --> 00:22:25,310
hemm din l-ekwivalenza, huwa
fil-fatt il-każ fir-realtà.

511
00:22:25,310 --> 00:22:28,000
Allura modifika ta 'malajr ta' din.

512
00:22:28,000 --> 00:22:31,220
Let me jiftħu ascii-1.c.

513
00:22:31,220 --> 00:22:38,070
U Avviż dan għaqlija, sort
ta ', kjarifika ta' dan.

514
00:22:38,070 --> 00:22:41,770
Dan huwa ASCII-1.c, u
Avviż dan ħaġa crazy.

515
00:22:41,770 --> 00:22:45,120
>> U dan verament gets il-qalb
ta 'dak kompjuters qed jagħmlu.

516
00:22:45,120 --> 00:22:48,150
Anki jekk aħna bnedmin kieku
Ma jgħoddux f'termini ta 'letters--

517
00:22:48,150 --> 00:22:50,380
I ma tibda taħseb,
id-dritt ta 'imbagħad b,

518
00:22:50,380 --> 00:22:52,590
u jużaw dawk li jgħoddu oġġetti fiżiċi.

519
00:22:52,590 --> 00:22:58,680
Inti tista 'ċertament ngħid li nixtieq li
initialize xi varjabbli imsejħa c--

520
00:22:58,680 --> 00:23:03,220
imma I setgħet sejjaħ dan anything--
hekk c huwa initialized għall-kapital A.

521
00:23:03,220 --> 00:23:07,560
>> Minħabba fl-aħħar tal-ġurnata, il-kompjuter
ma care dak li qed ħażna,

522
00:23:07,560 --> 00:23:10,170
biss jimpurtaha kif tixtieq
biex tippreżenta dik l-informazzjoni.

523
00:23:10,170 --> 00:23:13,560
Kif tridu l-kompjuter biex
tinterpreta dak il-mudell ta 'bits?

524
00:23:13,560 --> 00:23:16,320
Allura dan mhux xi ħaġa I
ġeneralment jirrakkomandaw tagħmel.

525
00:23:16,320 --> 00:23:19,500
Huwa tassew biss eżempju biex
twassal li inti tista 'assolutament

526
00:23:19,500 --> 00:23:22,049
initialize integer għal char.

527
00:23:22,049 --> 00:23:24,090
Minħabba taħtha l-
barnuża ta 'char, naturalment,

528
00:23:24,090 --> 00:23:26,170
huwa biss numru 0-255.

529
00:23:26,170 --> 00:23:28,540
>> Allura inti tista 'ċertament
poġġih ġewwa ta 'int.

530
00:23:28,540 --> 00:23:30,890
U dak li din ukoll
juri huwa li aħna

531
00:23:30,890 --> 00:23:34,040
jistgħu jikkonvertu minn waħda
tip għall-ieħor, hawnhekk,

532
00:23:34,040 --> 00:23:36,780
finalment istampar l-istess ħaġa.

533
00:23:36,780 --> 00:23:44,760
U fil-fatt, dan I se jiffissaw online--
kien maħsub biex ngħid dan, għal darb'oħra, here.

534
00:23:44,760 --> 00:23:48,610
Let me tnaddaf dan up online, u aħna ser
tara fi walkthrough online kif meħtieġ,

535
00:23:48,610 --> 00:23:50,280
dak li kien maħsub hemmhekk.

536
00:23:50,280 --> 00:23:50,960
>> OK.

537
00:23:50,960 --> 00:23:53,892
Allura aħħar eżempju issa jinvolvu
'A u B tal u allura aħna ser

538
00:23:53,892 --> 00:23:54,850
jieħdu l-affarijiet up a talja.

539
00:23:54,850 --> 00:23:58,330
Allura ma 'u tan-bu
tal Ċ fil-kapitalizzazzjoni

540
00:23:58,330 --> 00:24:01,560
u l-ekwivalenza tiegħu, ejja
tagħti ħarsa lejn dan l-eżempju, hawn.

541
00:24:01,560 --> 00:24:02,752
Eżempju ieħor kodiċi.

542
00:24:02,752 --> 00:24:04,460
Aħna ser tiftaħ waħda li
diġà sar, hekk aħna

543
00:24:04,460 --> 00:24:06,440
ma għandekx tip li
kollha barra mill-bidu.

544
00:24:06,440 --> 00:24:09,420
>> U avviż fil antiċipazzjoni
aħna qed jużaw header multiplu

545
00:24:09,420 --> 00:24:13,240
fajls, fosthom hija
ħabib ġdid tagħna, string.h.

546
00:24:13,240 --> 00:24:15,597
Issa dan jistenna, fl-ewwel
t'għajn, ftit cryptic.

547
00:24:15,597 --> 00:24:18,180
Imma ejja ara jekk ma nkunux nistgħu raġuni
permezz x'inhu għaddej hawn.

548
00:24:18,180 --> 00:24:21,150
Ewwel I nikseb string mill-utent,
u nressaq li string fi varjabbli

549
00:24:21,150 --> 00:24:22,286
imsejħa s.

550
00:24:22,286 --> 00:24:24,090
Kopja paste minn qabel.

551
00:24:24,090 --> 00:24:27,250
F'konformità 22, jien apparentement
tagħmel eżattament dak

552
00:24:27,250 --> 00:24:30,760
Jien għamilt mument ilu, jien mtennija
fuq il-karattri fit s.

553
00:24:30,760 --> 00:24:34,780
>> U l-tricks ġodda hawn huma jużaw
tul string, l-ottimizzazzjoni minuri

554
00:24:34,780 --> 00:24:37,930
tal-ħażna tul string fil n,
pjuttost milli ssejjaħ strlen darb'oħra,

555
00:24:37,930 --> 00:24:38,850
u għal darb'oħra, u għal darb'oħra.

556
00:24:38,850 --> 00:24:41,120
U biss verifika li i huwa inqas minn n.

557
00:24:41,120 --> 00:24:43,330
Issa hawnhekk, affarijiet nikseb
ftit interessanti.

558
00:24:43,330 --> 00:24:45,980
Iżda huwa biss applikazzjoni
ta 'dan l-istess idea ġdida.

559
00:24:45,980 --> 00:24:48,470
Liema bl-Ingliż ma
bracket s i jirrappreżenta?

560
00:24:48,470 --> 00:24:51,772

561
00:24:51,772 --> 00:24:54,260
>> UDJENZA: għadd ta 'kull
karattru [inaudible].

562
00:24:54,260 --> 00:24:55,926
>> DAVID J. Malan: għadd kull karattru.

563
00:24:55,926 --> 00:24:58,680
U anke aktar konċiż,
bracket s i jirrappreżentaw liema?

564
00:24:58,680 --> 00:25:00,950
Would you say.

565
00:25:00,950 --> 00:25:04,084
Mhux biex tpoġġi lilek fuq il-post hawn.

566
00:25:04,084 --> 00:25:06,375
>> UDJENZA: Well--

567
00:25:06,375 --> 00:25:09,500
DAVID J. Malan: Allura jekk il-kelma is-- jekk
il-sekwenza huwa Zamyla, li starts--

568
00:25:09,500 --> 00:25:12,380
UDJENZA: --you jittrattaw
il-karattri separately--

569
00:25:12,380 --> 00:25:13,690
DAVID J. Malan: Tajba.

570
00:25:13,690 --> 00:25:14,190
Eżattament.

571
00:25:14,190 --> 00:25:17,940
Il notazzjoni bracket kwadru jippermettilek
jaċċessaw kull karattru individwalment,

572
00:25:17,940 --> 00:25:21,120
hekk i bracket 0 se tkun l-
ewwel karattru fil-sekwenza.

573
00:25:21,120 --> 00:25:24,110
bracket s 1 se tkun
it-tieni, u ibqa 'sejjer hekk.

574
00:25:24,110 --> 00:25:28,050
Għalhekk il-kwistjoni jien tistaqsi,
hawn, f'din il-kundizzjoni huwa dak?

575
00:25:28,050 --> 00:25:33,984
Huwa l-karattru i'th ta 'aktar i
minn jew ugwali għal zghar a?

576
00:25:33,984 --> 00:25:36,400
U dak li jfisser dan, hawn,
mal-ampersands doppja?

577
00:25:36,400 --> 00:25:36,800
UDJENZA (FLIMKIEN): U.

578
00:25:36,800 --> 00:25:37,210
DAVID J. Malan: U.

579
00:25:37,210 --> 00:25:38,418
Huwa biss ekwivalenti għal dan.

580
00:25:38,418 --> 00:25:42,310
U mhix keyword fis-C, inti għandek
użu, annoyingly, ampersand ampersand.

581
00:25:42,310 --> 00:25:47,520
U dan, għall-kuntrarju, hija tistaqsi hija
i tal i'th karattru inqas minn jew ugwali

582
00:25:47,520 --> 00:25:49,030
biex zghar z?

583
00:25:49,030 --> 00:25:52,440
U għal darb'oħra, hawn fejn
jifhmu l-sottostanti

584
00:25:52,440 --> 00:25:54,550
implimentazzjoni ta '
kompjuter jagħmel sens.

585
00:25:54,550 --> 00:25:57,330
Avviż li, anki jekk I jkollhom
l-dot dot dot hemmhekk,

586
00:25:57,330 --> 00:26:04,410
qisu permezz z fl zghar huma
Valuri kontigwi kollha up mill-97 fuq up.

587
00:26:04,410 --> 00:26:07,820
>> U istess għall uppercase jibdew f'65.

588
00:26:07,820 --> 00:26:10,410
Allura l-takeaway, imbagħad,
hija li fil-Ingliż,

589
00:26:10,410 --> 00:26:12,760
Kif tiddeskrivi
liema linja 24 qed tagħmel?

590
00:26:12,760 --> 00:26:15,736

591
00:26:15,736 --> 00:26:16,728
Yeah?

592
00:26:16,728 --> 00:26:21,575
>> UDJENZA: Fl-24 huwa verifika biex tara
jekk kull karattru huwa zghar.

593
00:26:21,575 --> 00:26:24,700
DAVID J. Malan: Huwa verifika jekk
kull karattru hija ittra zghar.

594
00:26:24,700 --> 00:26:28,590
Hekk anke aktar konċiż, hija l-
karattru i'th tal zghar i?

595
00:26:28,590 --> 00:26:30,690
Li kollox aħna qed
jesprimu hawn loġikament,

596
00:26:30,690 --> 00:26:33,750
ftit cryptically, imma
finalment pretty jinftiehem.

597
00:26:33,750 --> 00:26:36,480
Hija S tal i'th zghar karattru?

598
00:26:36,480 --> 00:26:40,130
>> Jekk iva, u hawn fejn l-affarijiet
jiksbu mind ftit liwi

599
00:26:40,130 --> 00:26:44,760
għal ftit mument, jekk iva, imorru
quddiem u jistampa karattru.

600
00:26:44,760 --> 00:26:47,360
Allura dan huwa biss placeholder,
imma dak karattru?

601
00:26:47,360 --> 00:26:53,710
Why am I tagħmel bracket s i
minus din l-espressjoni hawn?

602
00:26:53,710 --> 00:26:55,110
>> Ukoll avviż l-mudell hawnhekk.

603
00:26:55,110 --> 00:26:57,380
In-numri reali ma jimpurtax tant.

604
00:26:57,380 --> 00:27:02,700
Iżda avviż li 97 hija
kemm bogħod mill 65?

605
00:27:02,700 --> 00:27:03,560
>> UDJENZA: 32.

606
00:27:03,560 --> 00:27:04,480
>> DAVID J. Malan: 32.

607
00:27:04,480 --> 00:27:06,890
Kemm bogħod huwa 98 minn 66?

608
00:27:06,890 --> 00:27:07,740
>> UDJENZA: 32.

609
00:27:07,740 --> 00:27:09,890
>> DAVID J. Malan: Little c minn C big?

610
00:27:09,890 --> 00:27:10,420
32.

611
00:27:10,420 --> 00:27:14,550
Allura hemm 32-ħops minn
ittra waħda għall-ieħor.

612
00:27:14,550 --> 00:27:17,790
So franchement I, jistgħu
jissimplifika dan għal dak.

613
00:27:17,790 --> 00:27:20,400
Imma mbagħad jien tip ta 'diffiċli' kodifikazzjoni
dan il-fehim livell baxx

614
00:27:20,400 --> 00:27:21,740
li l-ebda qarrej huwa qatt
ser jifhmu.

615
00:27:21,740 --> 00:27:25,080
So jien ser tiġġeneralizza bħala, I
jafu l-ittri lowercase huma akbar.

616
00:27:25,080 --> 00:27:28,400
I know-ittri kapitali huma
Valuri iżgħar, ironikament.

617
00:27:28,400 --> 00:27:33,216
>> Iżda din hija effettivament ekwivalenti għal
qal naqqas 32 mill parentesi s i.

618
00:27:33,216 --> 00:27:35,430
Allura fil-kuntest ta 'dawn
ittri, jekk l-ittra

619
00:27:35,430 --> 00:27:38,950
jiġri li jkun, lowercase
a, u I naqqas 32,

620
00:27:38,950 --> 00:27:43,442
x'effett ma li jkollhom,
matematikament, fuq zghar a?

621
00:27:43,442 --> 00:27:44,400
UDJENZA: Capitalizes--

622
00:27:44,400 --> 00:27:45,691
DAVID J. Malan: tikkapitalizza dan.

623
00:27:45,691 --> 00:27:48,440
U fil-fatt, dan huwa għaliex tagħna
programm huwa msejjaħ kapitalizzazzjoni żero.

624
00:27:48,440 --> 00:27:51,590
Dan il-programm jew
tikkapitalizza ittra,

625
00:27:51,590 --> 00:27:54,580
wara verifika jekk huwa
tabilħaqq ittra zghar.

626
00:27:54,580 --> 00:27:59,810
Inkella, fil-linja 30, x'għandi nagħmel jekk
huwa mhux ittra lowercase li jien

627
00:27:59,810 --> 00:28:02,852
tħares lejn lejn partikolari
iterazzjoni fil-linja.

628
00:28:02,852 --> 00:28:03,890
Just ipprintjaha.

629
00:28:03,890 --> 00:28:07,010
>> Allura ma jbiddlux Jittieħed
li mhux anki zghar.

630
00:28:07,010 --> 00:28:10,790
Illimita lilek innifsek biex
ftit li permezz ftit z.

631
00:28:10,790 --> 00:28:12,730
Issa dan huwa pjuttost arcane.

632
00:28:12,730 --> 00:28:15,230
Iżda fl-aħħar tal-ġurnata, dan
huwa kif aħna, darba fuq żmien,

633
00:28:15,230 --> 00:28:16,460
kellhom jimplimentaw affarijiet.

634
00:28:16,460 --> 00:28:19,780
Jekk I minflok tiftaħ kapitalizzazzjoni
wieħed, oh thank god.

635
00:28:19,780 --> 00:28:22,320
Hemm funzjoni
msejħa biex fuq li jistgħu

636
00:28:22,320 --> 00:28:25,410
do kollox aħna biss għamlet
fuq livell pjuttost baxx.

637
00:28:25,410 --> 00:28:28,752
>> Issa biex fuq huwa interessanti
minħabba li huwa ddikjarat fil-fajl,

638
00:28:28,752 --> 00:28:31,210
u inti biss taf dan
billi tiċċekkja d-dokumentazzjoni,

639
00:28:31,210 --> 00:28:35,730
jew jghidulek, ngħidu aħna, fil-klassi, fejn
teżisti, fil fajl imsejjaħ ctype.h.

640
00:28:35,730 --> 00:28:37,630
Allura dan huwa ħabib ieħor ġdid ta 'tagħna.

641
00:28:37,630 --> 00:28:40,750
U biex fuq ma eżattament
dak l-isem stess jissuġġerixxi.

642
00:28:40,750 --> 00:28:44,860
>> Inti tista 'tgħaddi fil-, bħala argument, bejn
dawn parentesi, xi karattru.

643
00:28:44,860 --> 00:28:48,390
Jien ser jgħaddu fil-karattru i'th
ta 'S użu notazzjoni ġdida tagħna fancy

644
00:28:48,390 --> 00:28:49,870
jinvolvu parentesi kwadri.

645
00:28:49,870 --> 00:28:53,391
U tieħu raden, dak huwa r-ritorn
valur ta 'li fuq apparentement tmur

646
00:28:53,391 --> 00:28:53,890
li tkun?

647
00:28:53,890 --> 00:28:56,460

648
00:28:56,460 --> 00:28:57,770
A ittra kapitali.

649
00:28:57,770 --> 00:28:58,620
A ittra kapitali.

650
00:28:58,620 --> 00:29:02,330
>> Mela jekk jien jgħaddu fi zghar a,
nisperaw, b'definizzjoni ta lil ta 'fuq,

651
00:29:02,330 --> 00:29:05,600
li għaddej biex jirritorna l
uppercase A. Inkella,

652
00:29:05,600 --> 00:29:08,590
jekk mhuwiex ittra zghar fil
l-ewwel post, I biss print it out.

653
00:29:08,590 --> 00:29:10,800
U fil-fatt, avviż-
tieni ħabib hawn.

654
00:29:10,800 --> 00:29:13,840
Mhux biss biex fuq teżisti,
imma hija inqas, li

655
00:29:13,840 --> 00:29:16,200
attwalment iwieġeb din id-domanda għalija.

656
00:29:16,200 --> 00:29:19,730
>> Issa min kiteb dawn l-affarijiet,
10s ta 'snin ilu, inti taf liema?

657
00:29:19,730 --> 00:29:23,840
Implimentati biex fuq u huwa
iktar baxxa li jużaw kodiċi bħal dan.

658
00:29:23,840 --> 00:29:27,270
Iżda għal darb'oħra, konsistenti mal-
din l-idea ta 'abstracting bogħod,

659
00:29:27,270 --> 00:29:29,190
tip ta ', livell aktar baxx
dettalji tal-implimentazzjoni.

660
00:29:29,190 --> 00:29:32,600
U wieqfa fuq l-ispallejn ta 'nies
li daħlu qabel magħna, bl-użu funzjonijiet

661
00:29:32,600 --> 00:29:36,300
simili li fuq u huwa inqas, li
wonderfully biżżejjed huma nicely

662
00:29:36,300 --> 00:29:40,190
jismu li jgħidu dak li jagħmlu, huwa
paradigma mill-isbaħ li jadottaw.

663
00:29:40,190 --> 00:29:44,040
>> Issa, jirriżulta li jekk I taqra
il-paġna bniedem għal, ngħidu, biex fuq,

664
00:29:44,040 --> 00:29:45,010
I jitgħallmu xi ħaġa oħra.

665
00:29:45,010 --> 00:29:46,890
Allura bniedem toUpper.

666
00:29:46,890 --> 00:29:48,050
Huwa ftit kbira.

667
00:29:48,050 --> 00:29:51,110
Iżda avviż, hawnhekk li aċċenn
il-fajl header li għandi jużaw.

668
00:29:51,110 --> 00:29:54,460
Bħala twarrib, għaliex dan
hija qarrieqa, il-funzjoni

669
00:29:54,460 --> 00:29:59,070
użi ints minflok Chars
għal raġunijiet ta 'żball iċċekkjar.

670
00:29:59,070 --> 00:30:01,260
Iżda aħna ser forsi jaslu
lura għal dak fil-futur.

671
00:30:01,260 --> 00:30:05,910
>> Iżda avviż, hawn, biex tikkonverti 'fuq
l-ittra c sabiex uppercase jekk possibbli.

672
00:30:05,910 --> 00:30:07,674
Allura dak pjuttost sempliċi.

673
00:30:07,674 --> 00:30:09,340
U issa ejja jkun ftit aktar speċifiku.

674
00:30:09,340 --> 00:30:12,750
Ejja nħarsu lejn l-parti tal-
paġna bniedem taħt il-valur tar-ritorn.

675
00:30:12,750 --> 00:30:15,420
Il-valur irritornat huwa li
tal-ittra konvertiti.

676
00:30:15,420 --> 00:30:18,690
Jew c, jekk il-konverżjoni
ma kienx possibbli,

677
00:30:18,690 --> 00:30:20,250
fejn c hija l-input oriġinali.

678
00:30:20,250 --> 00:30:24,140
Liema Naf minn hawn, minn
l-argument li għal ta 'fuq.

679
00:30:24,140 --> 00:30:25,780
>> Allura x'inhi l-takeaway ta 'dan?

680
00:30:25,780 --> 00:30:28,060
Il-valur irritornat huwa li
tal-ittra konvertiti,

681
00:30:28,060 --> 00:30:32,110
jew c, l-ittra oriġinali, jekk
l-konverżjoni ma kienx possibbli.

682
00:30:32,110 --> 00:30:36,460
What titjib nista għalhekk
tagħmel it-tfassil kodiċi tiegħi?

683
00:30:36,460 --> 00:30:37,146
Yeah?

684
00:30:37,146 --> 00:30:38,810
>> UDJENZA: Inti tista 'tneħħi l-ieħor.

685
00:30:38,810 --> 00:30:40,810
DAVID J. Malan: I tista '
neħħi l-istqarrija inkella,

686
00:30:40,810 --> 00:30:42,510
u mhux biss l-istqarrija inkella.

687
00:30:42,510 --> 00:30:44,150
>> UDJENZA: Inti tista 'tneħħi [inaudible].

688
00:30:44,150 --> 00:30:46,310
>> DAVID J. Malan: I tista '
neħħi l-furketta kollu

689
00:30:46,310 --> 00:30:48,209
fit-triq, il-jekk inkella għal kollox.

690
00:30:48,209 --> 00:30:50,250
Allura fil-fatt, let me miftuħa
il-verżjoni finali ta 'din,

691
00:30:50,250 --> 00:30:55,540
kapitalizzazzjoni-2 u avviż kemm, jekk
inti se, sexy, il-kodiċi hija issa jkollna,

692
00:30:55,540 --> 00:31:00,040
f'dak stajt mnaqqas minn xi
seba 'jew hekk linji għal ftit erba,

693
00:31:00,040 --> 00:31:03,850
l-funzjonalità li I maħsuba
billi sempliċiment ssejjaħ biex fuq,

694
00:31:03,850 --> 00:31:09,410
tgħaddi fis-bracket i i, u l-istampar
, bl-placeholder% c,

695
00:31:09,410 --> 00:31:11,090
dan il-karattru partikolari.

696
00:31:11,090 --> 00:31:14,560
>> Issa forsi, hemm bug,
jew għall-inqas ir-riskju ta 'bug,

697
00:31:14,560 --> 00:31:15,350
f'dan il-programm.

698
00:31:15,350 --> 00:31:18,200
Hekk biss li jiġu lura
għal takeaway aktar kmieni,

699
00:31:18,200 --> 00:31:21,820
x'għandi I probabbilment wkoll tagħmel fil
dan il-programm li jagħmilha aktar b'saħħitha,

700
00:31:21,820 --> 00:31:24,974
sabiex ma jkun hemm l-ebda mod li tista
tiġrifa, anki f'każijiet rari?

701
00:31:24,974 --> 00:31:26,390
UDJENZA: Kun ċert li huwa mhux NULL.

702
00:31:26,390 --> 00:31:28,056
DAVID J. Malan: Kun ċert li huwa mhux NULL.

703
00:31:28,056 --> 00:31:31,030
Allura verament, biex jagħmlu dan super
xierqa, I għandhom jagħmlu xi ħaġa simili,

704
00:31:31,030 --> 00:31:35,300
jekk i ma tkunx NULL, allura
imorru quddiem u tesegwixxi

705
00:31:35,300 --> 00:31:38,470
dawn il-linji ta 'kodiċi, li
I jistgħu mbagħad inċiż bħal dik,

706
00:31:38,470 --> 00:31:39,870
u mbagħad titqiegħed fil Brace qrib tiegħi.

707
00:31:39,870 --> 00:31:41,550
Allura tajjeb irbit flimkien taż-żewġ ideat.

708
00:31:41,550 --> 00:31:42,429
Yeah?

709
00:31:42,429 --> 00:31:44,470
UDJENZA: Tista 'tuża
do filwaqt loop, minflok?

710
00:31:44,470 --> 00:31:47,270
DAVID J. Malan: Jista
I do do filwaqt loop?

711
00:31:47,270 --> 00:31:50,020
UDJENZA: --you tixtieq li tagħmel ċert
li inti fil-fatt [inaudible].

712
00:31:50,020 --> 00:31:51,728
DAVID J. Malan: Jista
tuża do filwaqt?

713
00:31:51,728 --> 00:31:52,450
Risposta qasira, l-ebda.

714
00:31:52,450 --> 00:31:54,700
Għaliex int ser
jintroduċu każ ieħor kantuniera.

715
00:31:54,700 --> 00:31:56,660
Jekk il-sekwenza huwa ta 'tul żero.

716
00:31:56,660 --> 00:31:59,600
Jekk per eżempju, I biss hit
Ikteb, mingħajr qatt ittajpjar Zamyla.

717
00:31:59,600 --> 00:32:02,490
Jien ser inti idejn lura attwali
string, kif aħna ser eventwalment tara,

718
00:32:02,490 --> 00:32:03,780
li għandha żero karattri.

719
00:32:03,780 --> 00:32:05,630
Huwa għadu string,
huwa biss super qasir.

720
00:32:05,630 --> 00:32:07,960
Imma jekk inti tuża do waqt,
int ser addoċċ

721
00:32:07,960 --> 00:32:10,050
jipprova jagħmel xi ħaġa ma '
rigward ta 'dik string,

722
00:32:10,050 --> 00:32:12,537
u xejn għaddej biex jkun hemm.

723
00:32:12,537 --> 00:32:18,607
>> UDJENZA: Well, jekk inti ma
do [inaudible] filwaqt S--

724
00:32:18,607 --> 00:32:21,190
DAVID J. Malan: Oh I see, iżommu
jkollna string mill-utent.

725
00:32:21,190 --> 00:32:23,525
Tweġiba tant qasir, inti
jista, u jżommu pestering

726
00:32:23,525 --> 00:32:26,150
biex jagħtuk string li l-
qasir biżżejjed li jitwaħħal fil-memorja.

727
00:32:26,150 --> 00:32:26,700
Assolutament.

728
00:32:26,700 --> 00:32:27,630
I biss għażlet li ma.

729
00:32:27,630 --> 00:32:30,505
Jekk dawn ma jagħtux me-sekwenza I
tixtieq, jien jaqtagħhom, jien jċedu.

730
00:32:30,505 --> 00:32:33,260
Iżda assolutament, għal dak l-iskop,
inti tista 'assolutament tagħmel dan.

731
00:32:33,260 --> 00:32:37,500
>> Allura fajls header tal-librerija li
aħna qed issa familjari ma huma dawn, here.

732
00:32:37,500 --> 00:32:41,550
Standard I / O, CS50.h, string.h,
ctype.h, u hemm, tabilħaqq, oħrajn.

733
00:32:41,550 --> 00:32:44,460
Xi wħud minnkom skoprew
il-librerija matematika fl math.h.

734
00:32:44,460 --> 00:32:48,200
Imma let me jintroduċu inti, issa, biex
din ir-riżorsa li l-persunal CS50, Davin,

735
00:32:48,200 --> 00:32:50,630
u Rob, u Gabe partikolari
poġġew flimkien.

736
00:32:50,630 --> 00:32:52,630
Li dalwaqt se link fuq
websajt tal-kors tal-.

737
00:32:52,630 --> 00:32:54,870
Huwa sejjaħ referenza CS50.

738
00:32:54,870 --> 00:32:58,230
>> Liema biss biex jagħtuk quick
togħma ta 'dan, xogħlijiet kif ġej.

739
00:32:58,230 --> 00:33:00,740
Let me mur reference.cs50.net.

740
00:33:00,740 --> 00:33:02,990
Int ser ikollok tara fuq in-naħa tax-xellug
ġenb lista kbira

741
00:33:02,990 --> 00:33:04,595
tal-funzjonijiet li jiġu mal c.

742
00:33:04,595 --> 00:33:07,790
Imma jekk I kura, għall-mument,
dwar xi ħaġa bħal strlen,

743
00:33:07,790 --> 00:33:08,746
I tista tip hemmhekk.

744
00:33:08,746 --> 00:33:10,870
Hija filtri jistabbilixxi l-lista
li biss dak I care about.

745
00:33:10,870 --> 00:33:11,940
Jien ser ikklikkja dan.

746
00:33:11,940 --> 00:33:14,740
U issa fuq ix-xellug,
tkun taf tara dak li aħna nittamaw

747
00:33:14,740 --> 00:33:18,290
huwa aktar sempliċi, umani
spjegazzjoni friendly ta 'kif

748
00:33:18,290 --> 00:33:19,170
din il-funzjoni jaħdem.

749
00:33:19,170 --> 00:33:20,600
>> Denunzji-tul ta 'sekwenza.

750
00:33:20,600 --> 00:33:24,060
Hawn sinopsi, hawnhekk kif inti
tużah f'termini tal-fajl header,

751
00:33:24,060 --> 00:33:27,430
u f'termini ta 'dak li l-funzjoni
Dehra f'termini ta 'l-argumenti tagħha.

752
00:33:27,430 --> 00:33:30,250
U allura hawnhekk, prospetti
it-tul ta 'sekwenza.

753
00:33:30,250 --> 00:33:34,280
Iżda għal dawk tal inti aktar komda,
inti tista 'attwalment ikklikkja aktar comfy,

754
00:33:34,280 --> 00:33:37,070
u l-kontenut ta 'dan
paġna, issa, se jinbidlu

755
00:33:37,070 --> 00:33:41,660
li jkun il-valuri awtomatiċi ta 'dak li
ikollok billi tuża il-paġna bniedem.

756
00:33:41,660 --> 00:33:44,100
>> Fi kliem ieħor, CS50
referenza hija simplifikazzjoni

757
00:33:44,100 --> 00:33:46,220
ta 'paġni bniedem mill-persunal, għall-istudenti.

758
00:33:46,220 --> 00:33:49,320
Partikolarment, dawk inqas komdi
u fl bejn, sabiex inti

759
00:33:49,320 --> 00:33:51,660
ma għandekx biex jippruvaw biex nagħlaq
moħħok madwar, franchement,

760
00:33:51,660 --> 00:33:55,030
xi sintassi pjuttost cryptic
u dokumentazzjoni f'xi.

761
00:33:55,030 --> 00:33:57,650
>> Sabiex iżommu dan f'moħħhom
fil-jiem li ġejjin.

762
00:33:57,650 --> 00:33:59,560
Allura hawnhekk, għal darb'oħra, huwa Zamyla.

763
00:33:59,560 --> 00:34:03,255
Ejja issa jistaqsu mistoqsija li l-
ftit aktar umana aċċessibbli.

764
00:34:03,255 --> 00:34:05,380
Grazzi għall Chang, li kien
istampar aktar iljunfanti

765
00:34:05,380 --> 00:34:07,090
nonstop għall-aħħar ftit jiem.

766
00:34:07,090 --> 00:34:09,730
Għandna l-opportunità li jagħtu
mill-inqas wieħed minnhom bogħod.

767
00:34:09,730 --> 00:34:13,239
Jekk nistgħu tikseb wieħed biss voluntier
li ġejjin fuq up biex ifasslu fuq l-iskrin.

768
00:34:13,239 --> 00:34:14,530
Kif dwar hawn?

769
00:34:14,530 --> 00:34:15,340
>> Come fuq up.

770
00:34:15,340 --> 00:34:16,720
X'inhu l-isem tiegħek?

771
00:34:16,720 --> 00:34:17,219
ALEX: Alex.

772
00:34:17,219 --> 00:34:17,760
DAVID J. Malan: Alex.

773
00:34:17,760 --> 00:34:18,259
Kull dritt.

774
00:34:18,259 --> 00:34:19,388
Alex, come fuq up.

775
00:34:19,388 --> 00:34:21,679
Aħna waslet biex tara tiegħek
kalligrafija fuq l-iskrin hawn.

776
00:34:21,679 --> 00:34:24,325

777
00:34:24,325 --> 00:34:25,570
Kull dritt, sbieħ li jissodisfaw inti.

778
00:34:25,570 --> 00:34:26,429
>> ALEX: Nizza inti tissodisfa inti.

779
00:34:26,429 --> 00:34:27,512
>> DAVID J. Malan: Kull dritt.

780
00:34:27,512 --> 00:34:28,969
Allura, l-eżerċizzju super sempliċi.

781
00:34:28,969 --> 00:34:31,440
Bar mhuwiex għoli li
tikseb iljunfant llum.

782
00:34:31,440 --> 00:34:33,439
Inti qed jilagħbu l-irwol ta 'getstring.

783
00:34:33,439 --> 00:34:35,980
U jien ser jgħidlek biss
l-sekwenza li inti stajt gotten.

784
00:34:35,980 --> 00:34:38,080
U jissoponi li inti,
getstring, ġew imsejħa.

785
00:34:38,080 --> 00:34:42,480
U l-bniedem, bħali, għandha
ittajpjat fil Zamyla, Z-A-M-Y-L-A.

786
00:34:42,480 --> 00:34:45,650
Just go quddiem u jiktbu Zamyla fuq il-
screen daqslikieku inti gotten dan

787
00:34:45,650 --> 00:34:47,250
u maħżuna x'imkien fil-memorja.

788
00:34:47,250 --> 00:34:52,370

789
00:34:52,370 --> 00:34:55,570
>> Leaving kamra għal dak li se jkun diversi
words-- ieħor li OK, iżommu għaddejjin.

790
00:34:55,570 --> 00:34:59,620
>> [Rires]

791
00:34:59,620 --> 00:35:00,800
>> Allura Zamyla, Eċċellenti.

792
00:35:00,800 --> 00:35:04,880
Allura issa jissoponi li inti,
getstring, huma msejħa mill-ġdid.

793
00:35:04,880 --> 00:35:09,350
U għalhekk, I jagħtuk, fil-
keyboard, ma 'isem ieħor, Belinda.

794
00:35:09,350 --> 00:35:17,560

795
00:35:17,560 --> 00:35:18,060
Kull dritt.

796
00:35:18,060 --> 00:35:22,380
U issa l-getstring ħin li jmiss hu
imsejħa, I tip fil xi ħaġa simili Gabe,

797
00:35:22,380 --> 00:35:27,560
G-A-B E. Int verament tieħu
qalb memorja t'aċċess bl-addoċċ.

798
00:35:27,560 --> 00:35:29,631
Liema hija tpinġija kollox
kompletament saltwarjament.

799
00:35:29,631 --> 00:35:30,130
OK.

800
00:35:30,130 --> 00:35:31,104
>> [Rires]

801
00:35:31,104 --> 00:35:32,520
ALEX: Jiddispjacini kalligrafija tiegħi huwa ħażin.

802
00:35:32,520 --> 00:35:33,770
DAVID J. Malan: Le, li OK.

803
00:35:33,770 --> 00:35:40,480
U kif madwar Rob, R-O-B. OK.

804
00:35:40,480 --> 00:35:41,020
Tajba.

805
00:35:41,020 --> 00:35:43,853
So I ma tantiċipa inti
tip ta jistabbilixxu affarijiet f'din il-mod.

806
00:35:43,853 --> 00:35:45,020
Iżda nistgħu nagħmlu dan ix-xogħol.

807
00:35:45,020 --> 00:35:48,810
Allura kif ma inti tmur dwar li
out dawn Chars fil-memorja?

808
00:35:48,810 --> 00:35:51,310
Fi kliem ieħor, jekk naħsbu ta '
dan l-iskrin iswed rettangolari

809
00:35:51,310 --> 00:35:53,550
bħala li jirrappreżentaw
RAM, jew memorja tal-kompjuter.

810
00:35:53,550 --> 00:35:55,850
>> U tfakkar li RAM huwa biss
mazz sħiħ ta 'bytes,

811
00:35:55,850 --> 00:35:57,480
u bytes huma mazz sħiħ ta 'bits.

812
00:35:57,480 --> 00:35:59,350
U bits huma b'xi mod
implimentati, ġeneralment

813
00:35:59,350 --> 00:36:01,119
ma 'xi forma ta'
elettriku fil-hardware.

814
00:36:01,119 --> 00:36:03,160
Allura dak it-tip ta 'l-
saffi konna tkellimna dwar

815
00:36:03,160 --> 00:36:04,510
u issa tista 'tieħu għall mogħtija.

816
00:36:04,510 --> 00:36:07,020
Kif ma inti tmur dwar
jiddeċiedu fejn jiktbu

817
00:36:07,020 --> 00:36:11,634
Rob versus Gabe versus
Belinda versus Zamyla?

818
00:36:11,634 --> 00:36:14,020
>> ALEX: I biss ma kien fil-
tordna li inti told me.

819
00:36:14,020 --> 00:36:15,650
>> DAVID J. Malan: U li huwa veru.

820
00:36:15,650 --> 00:36:20,100
Imma dak regolati fejn inti tpoġġi
Isem Belinda u l-isem Gabe tal?

821
00:36:20,100 --> 00:36:20,764
>> ALEX: Xejn?

822
00:36:20,764 --> 00:36:22,930
DAVID J. Malan: [Laughs]
Allura li jaħdem, li l-multa.

823
00:36:22,930 --> 00:36:25,290
Allura kompjuters huma ftit
aktar ordnat minn dak.

824
00:36:25,290 --> 00:36:29,000
U hekk meta aħna implement-- jibqgħu hemm
għal ftit moment-- meta aħna attwalment

825
00:36:29,000 --> 00:36:31,470
jimplimentaw xi ħaġa bħal
getstring fil-kompjuter,

826
00:36:31,470 --> 00:36:34,480
Zamyla jista 'jiġi stabbiliti pretty ħafna
bħal għamilt fuq l-iskrin, hemm.

827
00:36:34,480 --> 00:36:36,660
>> U dak li huwa importanti li l-avviż
hawn, dak Alex għamlet,

828
00:36:36,660 --> 00:36:40,260
hija li hemm tip ta 'demarkazzjoni
fost kull wieħed minn dawn il-kliem, id-dritt?

829
00:36:40,260 --> 00:36:46,580
Inti ma jiktbu
Z-A-M-Y-L-A-B-E-L-I-N-D-A-G-A-B--

830
00:36:46,580 --> 00:36:49,740
fi kliem ieħor, hemm xi tip
ta 'demarkazzjoni li jidher li jkun,

831
00:36:49,740 --> 00:36:52,370
tip ta ', ispazjar każwali
bejn dawn il-kliem differenti.

832
00:36:52,370 --> 00:36:54,120
Imma li tajjeb, għaliex
aħna bnedmin issa jistgħu

833
00:36:54,120 --> 00:36:56,470
Ħares li dawn huma
erba kordi differenti.

834
00:36:56,470 --> 00:36:59,540
Huwa mhux biss sekwenza waħda
ta 'lottijiet ta' karattri.

835
00:36:59,540 --> 00:37:04,190
Allura kompjuter, imbagħad, sadanittant,
jista 'jieħu string bħal Zamyla,

836
00:37:04,190 --> 00:37:07,220
tpoġġi kull wieħed minn dawn l-ittri
ġewwa ta 'byte ta' memorja.

837
00:37:07,220 --> 00:37:10,400
Iżda dan in-numru huwa ħafna akbar,
naturalment, minn sitt karattri.

838
00:37:10,400 --> 00:37:11,690
>> Hemm mazz sħiħ ta 'RAM.

839
00:37:11,690 --> 00:37:15,330
U hekk issa, dan
grid ta 'kaxxi li qed jiġri

840
00:37:15,330 --> 00:37:17,560
biex jirrappreżentaw dak Alex biss
għamlet hawn fuq l-iskrin.

841
00:37:17,560 --> 00:37:20,937
U issa, Alex, nistgħu noffrulek
blu jew iljunfant oranġjo minn Chang.

842
00:37:20,937 --> 00:37:22,270
ALEX: I ser tieħu iljunfant blu.

843
00:37:22,270 --> 00:37:23,120
DAVID J. Malan: A iljunfant blu.

844
00:37:23,120 --> 00:37:25,580
Allura rawnd kbir ta 'applause,
jekk nistgħu, għal Alex hawn.

845
00:37:25,580 --> 00:37:26,100
>> [Applause]

846
00:37:26,100 --> 00:37:26,766
>> ALEX: Grazzi.

847
00:37:26,766 --> 00:37:28,820
DAVID J. Malan: Grazzi.

848
00:37:28,820 --> 00:37:36,230
Allura l-takeaway hija li, anki jekk il-
mudell tip ta inbidlet matul iż-żmien, hawn

849
00:37:36,230 --> 00:37:40,430
fuq il-bord, kien hemm dan
demarkazzjoni fost il-kordi varji

850
00:37:40,430 --> 00:37:42,610
li Alex ltqajna għalina.

851
00:37:42,610 --> 00:37:45,230
Issa kompjuters, franchement,
tista 'tagħmel l-istess ħaġa.

852
00:37:45,230 --> 00:37:48,210
Huma jistgħu tip ta 'plop
kordi kullimkien fil RAM.

853
00:37:48,210 --> 00:37:50,710
Up hawn, hawn fuq,
stabbiliti hawn, stabbiliti hawn.

854
00:37:50,710 --> 00:37:52,020
>> Huma jistgħu jagħmlu eżattament dan.

855
00:37:52,020 --> 00:37:54,280
Imma, naturalment, li l-
probabbilment mhux l-aħjar ippjanar.

856
00:37:54,280 --> 00:37:54,780
Right?

857
00:37:54,780 --> 00:37:57,340
Jekk I tinżamm tistaqsi Alex biex
tikseb l-ismijiet, probabbilment hu d

858
00:37:57,340 --> 00:38:01,370
jqajjem xi aktar stabbiliti hawn, forsi up
hawn, hawn, hawn fuq, eventwalment

859
00:38:01,370 --> 00:38:02,211
minn hawn.

860
00:38:02,211 --> 00:38:05,460
Iżda bi ftit aktar ippjanar, ċertament,
nistgħu jistabbilixxu affarijiet out aktar nadif.

861
00:38:05,460 --> 00:38:07,350
U fil-fatt, dan huwa dak kompjuter ma.

862
00:38:07,350 --> 00:38:10,720
>> Iżda l-qabda hija li
jekk il-string jmiss I nikseb

863
00:38:10,720 --> 00:38:14,050
wara Zamyla hija xi ħaġa
bħall-Belinda,

864
00:38:14,050 --> 00:38:17,929
tipproponi fejn nistgħu tikteb il-
ittra b rigward dan il grid?

865
00:38:17,929 --> 00:38:18,720
Fejn kieku inti tmur?

866
00:38:18,720 --> 00:38:21,480
Għad-dritt ta 'l-a,
taħt il-z, taħt il-a?

867
00:38:21,480 --> 00:38:23,204
X'għandu instincts tiegħek l-ewwel tkun?

868
00:38:23,204 --> 00:38:24,120
UDJENZA: Hawn taħt il-z.

869
00:38:24,120 --> 00:38:25,100
DAVID J. Malan: Allura taħt il-z.

870
00:38:25,100 --> 00:38:26,530
U li pretty
sempliċi, id-dritt?

871
00:38:26,530 --> 00:38:29,321
Huwa tip ta 'pulita, huwa dak li nagħmlu
fuq tastiera meta aħna hit Ikteb,

872
00:38:29,321 --> 00:38:31,770
jew email meta jagħmlu
lista bulleted ta 'affarijiet.

873
00:38:31,770 --> 00:38:34,310
Iżda r-realtà hija li l-kompjuters
jippruvaw ikunu aktar effiċjenti,

874
00:38:34,310 --> 00:38:37,170
u CRAM ċertament kemm
data fis RAM kemm jista 'jkun,

875
00:38:37,170 --> 00:38:38,890
sabiex inti ma jaħlux xi bytes.

876
00:38:38,890 --> 00:38:41,545
Allura li inti ma jaħlux
kwalunkwe proprjetà immobbli iskrin.

877
00:38:41,545 --> 00:38:44,170
U l-problema, għalkemm, hi li
jekk aħna litteralment tpoġġi l-ittra

878
00:38:44,170 --> 00:38:49,940
b wara, kif huma aħna se
taf fejn isem Zamyla jintemm

879
00:38:49,940 --> 00:38:51,840
u l-isem tal-Belinda tal jibda?

880
00:38:51,840 --> 00:38:55,270
Allura inti bnedmin biss proposta, ukoll,
laqat il Enter, essenzjalment.

881
00:38:55,270 --> 00:38:56,410
Poġġi l-isfel hawn taħt.

882
00:38:56,410 --> 00:38:59,750
Jew anke bħala Alex ma, biss tibda bil-miktub
l-isem li jmiss taħt dak preċedenti,

883
00:38:59,750 --> 00:39:01,583
u taħt dak waħda, u
allura hawn taħt li wieħed.

884
00:39:01,583 --> 00:39:02,510
Li l-CUÉ viżwali.

885
00:39:02,510 --> 00:39:05,960
>> Kompjuters jkollhom CUÉ viżwali ieħor,
iżda huwa ftit aktar imqassra.

886
00:39:05,960 --> 00:39:07,840
Huwa dan il-karattru funky.

887
00:39:07,840 --> 00:39:11,890
Backslash 0, li hija forsi
reminixxenti tal backslash n,

888
00:39:11,890 --> 00:39:12,640
u ibqa 'sejjer hekk, issa.

889
00:39:12,640 --> 00:39:14,120
Il-sekwenzi speċjali salvataġġ.

890
00:39:14,120 --> 00:39:19,120
Backslash 0 huwa l-mod ta '
li jirrappreżenta tmien żero bits fil-filliera.

891
00:39:19,120 --> 00:39:22,000
0000 0000.

892
00:39:22,000 --> 00:39:26,130
>> Il-mod inti tesprimi dan ma
laqat il-numru żero fuq it-tastiera tiegħek,

893
00:39:26,130 --> 00:39:28,140
minħabba fil-fatt li huwa char ASCII.

894
00:39:28,140 --> 00:39:30,990
Jidher qisu numru, iżda
huwa attwalment numru deċimali

895
00:39:30,990 --> 00:39:35,910
li tirrappreżenta l-ċirkolari
glyph, it-tipa ċirkolari.

896
00:39:35,910 --> 00:39:38,410
Sadanittant, backslash
żero litteralment tfisser

897
00:39:38,410 --> 00:39:40,700
tpoġġi tmien żero bytes hawn għalija.

898
00:39:40,700 --> 00:39:42,136
>> Allura dan huwa kemmxejn arbitrarja.

899
00:39:42,136 --> 00:39:44,260
We jistgħu stajt użat kwalunkwe mudell
ta 'bits, iżda fid-dinja

900
00:39:44,260 --> 00:39:46,610
iddeċieda xi snin
ilu, li jirrappreżentaw

901
00:39:46,610 --> 00:39:49,710
it-tmiem ta string fil-memorja,
biss jitqiegħed mazz sħiħ ta 'żerijiet.

902
00:39:49,710 --> 00:39:51,000
Għaliex nistgħu jikxfu dik.

903
00:39:51,000 --> 00:39:54,790
Issa li jfisser li l-ebda ittra ta 'l-
alfabett jista 'jiġi rappreżentat b'żero.

904
00:39:54,790 --> 00:39:58,480
>> Imma dak li OK, konna diġà raw
li aħna qed tuża 65 fuq up f'97 fuq up.

905
00:39:58,480 --> 00:40:00,290
Aħna ma jiksbu kullimkien
qrib żerijiet kollha.

906
00:40:00,290 --> 00:40:03,040

907
00:40:03,040 --> 00:40:06,540
Allura Belinda fil-memorja tal-kompjuter
huwa attwalment se jmorru hawn.

908
00:40:06,540 --> 00:40:09,764
Stajt irtirat hu isfar biss
tiġbed l-attenzjoni tagħna għaliha.

909
00:40:09,764 --> 00:40:11,680
U avviż, wisq, dan
huwa kompletament arbitrarja.

910
00:40:11,680 --> 00:40:12,680
Stajt mfassla bħala grilja.

911
00:40:12,680 --> 00:40:14,460
Bħal, RAM huwa biss xi oġġett fiżiku.

912
00:40:14,460 --> 00:40:17,300
Dan ma jfissirx neċessarjament ikollhom
ringieli u kolonni, per se.

913
00:40:17,300 --> 00:40:20,490
Huwa biss ltqajna mazz sħiħ ta 'bytes
implimentat fil-hardware b'xi.

914
00:40:20,490 --> 00:40:22,817
Imma jekk wara Belinda I
ittajpjat fl-isem Gabe, l

915
00:40:22,817 --> 00:40:25,650
huwa għaddej biex jispiċċaw hawn fil-memorja,
u jekk I ittajpjat fil isem Daven tal,

916
00:40:25,650 --> 00:40:27,316
per eżempju, huwa għaddej biex jispiċċaw here.

917
00:40:27,316 --> 00:40:29,310
U nista 'tkompli
jiktbu saħansitra aktar ismijiet.

918
00:40:29,310 --> 00:40:32,100
>> Sfortunatament, jekk nipprova
jiktbu isem twil super,

919
00:40:32,100 --> 00:40:33,730
I jista 'eventwalment jispiċċaw ta' memorja.

920
00:40:33,730 --> 00:40:37,810
F'liema każ, getstring huwa
ser jirritorna NULL, kif aħna qal.

921
00:40:37,810 --> 00:40:41,720
Iżda Thankfully, għall-inqas f'dan viżwali
hawn, aħna ma jiksbu pjuttost li s'issa.

922
00:40:41,720 --> 00:40:45,860
>> Issa x'hemm sbieħ hija li dan
idea ġenerali ta 'trattament affarijiet

923
00:40:45,860 --> 00:40:49,720
bħala fil-kaxxi huwa
rappreżentant ta 'karatteristika ta' C

924
00:40:49,720 --> 00:40:52,690
u ħafna ta 'lingwi,
magħrufa bħala firxa.

925
00:40:52,690 --> 00:40:55,490
Firxa hija tip ieħor ta 'data.

926
00:40:55,490 --> 00:40:57,380
Hija struttura data, jekk inti se.

927
00:40:57,380 --> 00:41:01,160
Struttura fis-sens ta 'dan verament,
tip ta ', tfittex bħal kaxxa, mill-inqas

928
00:41:01,160 --> 00:41:02,320
f'moħħu fl-għajnejn tiegħek.

929
00:41:02,320 --> 00:41:09,680
Firxa hija kontigwa
sekwenza ta 'tipi ta' data identiċi,

930
00:41:09,680 --> 00:41:11,330
lura lura lura biex lura.

931
00:41:11,330 --> 00:41:14,720
>> Allura string, fil-oħra
kliem, huwa firxa ta 'Chars.

932
00:41:14,720 --> 00:41:16,120
Firxa ta 'karattri.

933
00:41:16,120 --> 00:41:19,070
Iżda jirriżulta inti jista 'jkollhom
arrays ta 'għenieqed ta' affarijiet.

934
00:41:19,070 --> 00:41:21,870
Fil-fatt, nistgħu npoġġu anke
numri fil-firxa.

935
00:41:21,870 --> 00:41:23,920
Allura l-forma li fiha
aħna qed tmur biex tibda

936
00:41:23,920 --> 00:41:26,590
tiddikjara din id-data
struttura magħrufa bħala firxa

937
00:41:26,590 --> 00:41:28,250
huwa wkoll ser tuża parentesi kwadri.

938
00:41:28,250 --> 00:41:31,500
Iżda dawn parentesi kwadri huma ser
għandhom tifsira differenti f'dan il-kuntest.

939
00:41:31,500 --> 00:41:33,450
>> U ejja ara dan kif ġej.

940
00:41:33,450 --> 00:41:36,780
Ejja ngħidu li I fetaħ
up fajl ġdid hawn.

941
00:41:36,780 --> 00:41:38,535
U jien tiffranka dan bħala ages.c.

942
00:41:38,535 --> 00:41:41,280

943
00:41:41,280 --> 00:41:43,470
U jien ser tiffranka dan fil folder tiegħi hawn.

944
00:41:43,470 --> 00:41:46,130
U issa jien se jimxi 'l quddiem
u tibda ittajpjar xi ħaġa

945
00:41:46,130 --> 00:41:53,940
bħall jinkludu CS50.h, jinkludu
stdio.h, int null prinċipali.

946
00:41:53,940 --> 00:41:57,370
U mbagħad ġewwa ta 'hawn, nixtieq
li l-ewwel ikollhom int imsejħa età.

947
00:41:57,370 --> 00:42:01,371
>> U jien ser tuża li biex tikseb
int mill-utent għall-età tiegħu jew tagħha.

948
00:42:01,371 --> 00:42:04,620
Iżda dan il-programm huwa maħsub biex jintuża mill-
nies multipli, għal kwalunkwe kuntest.

949
00:42:04,620 --> 00:42:05,490
Stajt ltqajna linja ta 'nies.

950
00:42:05,490 --> 00:42:08,281
Kollha kemm għandek tip fil tagħhom
età għall forsi xi wħud, I do not know,

951
00:42:08,281 --> 00:42:10,530
kompetizzjoni, jew avveniment
li ħadthom waslu għal.

952
00:42:10,530 --> 00:42:13,030
Allura l-persuna li jmiss, I
bżonn ieħor varjabbli.

953
00:42:13,030 --> 00:42:15,790
>> Għaliex jekk I biss ma
età gets getInt, li

954
00:42:15,790 --> 00:42:18,500
tmur clobber, jew jissostitwixxu
età tal-persuna preċedenti.

955
00:42:18,500 --> 00:42:19,760
Allura li l-ebda tajba.

956
00:42:19,760 --> 00:42:21,790
Allura l-ewwel istint tiegħi
jista 'jkun, oh, id-dritt,

957
00:42:21,790 --> 00:42:26,260
jekk I rridu nġibu Popolari multipli
ages-- ejja sejħa dan age1,

958
00:42:26,260 --> 00:42:31,280
age2 int gets int, age3 int gets getInt.

959
00:42:31,280 --> 00:42:35,340
U issa jien ser tuża
xi kodiċi pseudocode hawn.

960
00:42:35,340 --> 00:42:37,679
>> Tagħmel xi ħaġa ma 'dawk in-numri.

961
00:42:37,679 --> 00:42:40,470
Aħna ser leave għal jum ieħor dak
li aħna qed tagħmel hemmhekk, għaliex aħna biss

962
00:42:40,470 --> 00:42:44,200
kura għall-mument
dwar age1, age2, age3.

963
00:42:44,200 --> 00:42:46,450
Sfortunatament, ladarba I
jiġbru dan il-programm

964
00:42:46,450 --> 00:42:51,140
u poġġih fil quddiem ta 'l-utenti attwali,
x'inhu l-disinn fundamentalment foqra

965
00:42:51,140 --> 00:42:53,890
deċiżjoni I jidhru li għamlu?

966
00:42:53,890 --> 00:42:54,624
Yeah?

967
00:42:54,624 --> 00:42:55,499
UDJENZA: [inaudible]

968
00:42:55,499 --> 00:42:58,071

969
00:42:58,071 --> 00:42:59,820
DAVID J. Malan: Yeah,
I ma anke ppruvaw

970
00:42:59,820 --> 00:43:02,028
biex insemmu kif etajiet ħafna
do I attwalment kura dwar?

971
00:43:02,028 --> 00:43:05,380
Jekk I għandhom inqas minn tliet persuni hawn,
u għalhekk inqas minn tliet etajiet,

972
00:43:05,380 --> 00:43:07,260
Jien xorta addoċċ jistennew tlieta.

973
00:43:07,260 --> 00:43:08,720
Alla jipprojbixxu erba 'persuni juru up.

974
00:43:08,720 --> 00:43:10,990
Programm tiegħi biss mhux se anki isostnuhom.

975
00:43:10,990 --> 00:43:13,280
>> U hekk dan, l-istorja twila
qasir, mhuwiex drawwa tajba.

976
00:43:13,280 --> 00:43:13,780
Right?

977
00:43:13,780 --> 00:43:16,530
I kien essenzjalment ikkupjar u
pasta kodiċi u biss tweaking

978
00:43:16,530 --> 00:43:17,430
l-ismijiet varjabbli.

979
00:43:17,430 --> 00:43:22,410
U, god tiegħi, jekk kellek, mhux tlieta
etajiet, iżda 10, jew 100, jew saħansitra 6,500

980
00:43:22,410 --> 00:43:23,820
ggradwawx, per eżempju.

981
00:43:23,820 --> 00:43:26,950
Dan mhux se tkun partikolarment
kodiċi eleganti, jew sostenibbli.

982
00:43:26,950 --> 00:43:29,200
Int ser ikollhom
jikteb il-programm kull darba

983
00:43:29,200 --> 00:43:30,760
numru tiegħek ta 'bidliet nies.

984
00:43:30,760 --> 00:43:35,090
>> Allura Thankfully, fil attwali tagħna
fajl ages.c għal-lum,

985
00:43:35,090 --> 00:43:36,970
għandna soluzzjoni aktar għaqlija.

986
00:43:36,970 --> 00:43:39,800
L-ewwel, jien ser tissellef il-
jinbena konna użati għal xi ftit drabi,

987
00:43:39,800 --> 00:43:43,744
dan tagħmel waqt loop, sabiex jiksbu
in-numru ta 'nies fil-kamra.

988
00:43:43,744 --> 00:43:46,910
Jien biss ser jiffittaw bis-utent, għal darb'oħra
u għal darb'oħra, sakemm hu jew hi tagħti me

989
00:43:46,910 --> 00:43:49,260
valur ta 'n thats numru sħiħ pożittiv.

990
00:43:49,260 --> 00:43:51,590
>> I setgħet użat, l-aħħar
time nneħħu int pożittiv.

991
00:43:51,590 --> 00:43:53,720
Iżda aħna ma jkollhomx dak
għall reali, so I marru quddiem

992
00:43:53,720 --> 00:43:55,660
u ri implimentata din l-idea.

993
00:43:55,660 --> 00:43:58,410
Issa stabbiliti hawn, dan huwa l-trick ġdid.

994
00:43:58,410 --> 00:44:02,260
F'konformità 27, bħala l-kummenti
fil-linja 26 tissuġġerixxi,

995
00:44:02,260 --> 00:44:05,180
jiddikjara firxa li fiha
biex jaħżnu l-età ta 'kulħadd.

996
00:44:05,180 --> 00:44:09,320
>> Mela jekk inti tixtieq li tikseb, ma int wieħed, ma
żewġ ints, iżda mazz sħiħ ta 'ints.

997
00:44:09,320 --> 00:44:13,800
Speċifikament n interi, n kienu jista
jkun tlieta, tista 'tkun ta' 100, jista 'jkun 1,000.

998
00:44:13,800 --> 00:44:17,570
Is-sintassi, pjuttost sempliċi, huwa li
jiġifieri, liema tip ta 'data li tridu?

999
00:44:17,570 --> 00:44:19,620
What do inti tixtieq li sejħa
li blokki ta 'memorja?

1000
00:44:19,620 --> 00:44:23,530
What do inti tixtieq li jsejħu l-grid
li tidher bħal dan pictorially?

1001
00:44:23,530 --> 00:44:27,700
>> U fil-parentesi hawn, inti tgħidli
kemm hu kbir inti tixtieq l-firxa li tkun.

1002
00:44:27,700 --> 00:44:30,450
U hekk qabel, meta I qal li l-
sintassi huwa xi ftit differenti hawn,

1003
00:44:30,450 --> 00:44:33,614
aħna qed għadhom qed jużaw parentesi kwadri,
imma meta jien tiddikjara firxa,

1004
00:44:33,614 --> 00:44:35,530
in-numru ġewwa tal-
parentesi kwadri mezzi

1005
00:44:35,530 --> 00:44:37,610
kemm hu kbir tridu l-firxa li tkun.

1006
00:44:37,610 --> 00:44:42,490
>> B'kuntrast, meta konna jużaw s
bracket i mument ilu, i, string,

1007
00:44:42,490 --> 00:44:46,820
huwa tabilħaqq firxa ta 'Chars, iżda
meta ma tkunx qed tiddikjara varjabbli,

1008
00:44:46,820 --> 00:44:49,760
kif ma 'dan il-keyword hawn,
int sempliċement jkollna

1009
00:44:49,760 --> 00:44:54,280
indiċi speċifiku, speċifika
element minn dak array.

1010
00:44:54,280 --> 00:44:57,090
Ladarba aħna nafu li, l-bqija
ta 'dan huwa sempliċi.

1011
00:44:57,090 --> 00:45:00,765
Jekk ġdid jien l-ewwel ser jistampa
x'inhu l-età ta 'persuna numru i.

1012
00:45:00,765 --> 00:45:03,890
Fejn I biss jgħidu numru persuna waħda,
persuna numru tnejn, persuna numru tlieta.

1013
00:45:03,890 --> 00:45:06,306
>> U jien biss tagħmel aritmetika,
hekk li bħal nies normali,

1014
00:45:06,306 --> 00:45:09,030
aħna għadd minn wieħed għal dan
programm, u mhux minn żero.

1015
00:45:09,030 --> 00:45:13,620
Imbagħad I call getint, imma I taħżen
ir-risposta fl-etajiet parentesi i.

1016
00:45:13,620 --> 00:45:16,610
Liema hija l-età i'th fil-firxa.

1017
00:45:16,610 --> 00:45:21,640
Allura billi aħħar darba konna trattament
dawn il-kaxxi bħala Chars għall-isem Zamyla'S,

1018
00:45:21,640 --> 00:45:22,490
u oħrajn.

1019
00:45:22,490 --> 00:45:26,530
Issa, dawn il-kaxxi jirrappreżentaw
32 bits, jew erba 'bytes

1020
00:45:26,530 --> 00:45:29,510
li aħna jista 'jaħżen
l int, xi int, l int.

1021
00:45:29,510 --> 00:45:31,890
Kollha li, għal darb'oħra,
huma l-istess tip ta 'data.

1022
00:45:31,890 --> 00:45:33,890
>> Now I tagħmel xi ħaġa iblah,
bħall jgħaddi żmien, biss

1023
00:45:33,890 --> 00:45:35,510
biex tiġġustifika miktub dan il-programm.

1024
00:45:35,510 --> 00:45:40,050
U mbagħad stabbiliti hawn, I darb'oħra jtenni
tul l-arranġament tgħid sena minn issa,

1025
00:45:40,050 --> 00:45:43,090
persuna għadd rieda waħda
ikun is-snin xi ħaġa qodma.

1026
00:45:43,090 --> 00:45:45,010
U biex insemmu li
math-- I mean, dan

1027
00:45:45,010 --> 00:45:49,260
mhux ħafna ikkumplikata arithmetic--
I biss żid waħda għall-età tagħhom.

1028
00:45:49,260 --> 00:45:51,240
Just biex juru, għal darb'oħra, dan.

1029
00:45:51,240 --> 00:45:57,910
>> Just kemm nista indiċi fi string, i,
hekk nista indiċi fi firxa ta 'etajiet,

1030
00:45:57,910 --> 00:45:59,950
bħal dik hemmhekk.

1031
00:45:59,950 --> 00:46:03,340
Għalhekk, fejn huwa dan se tkun qed tieħu lilna?

1032
00:46:03,340 --> 00:46:07,070
Allura aħna se tara, finalment, ta '
affarijiet ftit fil-jiem li ġejjin.

1033
00:46:07,070 --> 00:46:09,510
Wieħed, dan il-ħin, meta
kitba programmi tiegħek stess,

1034
00:46:09,510 --> 00:46:11,239
bħal Mario, greedy, kreditu.

1035
00:46:11,239 --> 00:46:13,780
You ħadthom ġiet jittajpja l-isem ta '
il-programm u laqtu Ikteb.

1036
00:46:13,780 --> 00:46:15,610
U allura jkollna input-utent.

1037
00:46:15,610 --> 00:46:18,137
>> Bil getString, getInt,
getLongLong, jew simili.

1038
00:46:18,137 --> 00:46:20,720
Iżda jirriżulta li jappoġġja Ċ
xi ħaġa imsejħa linja ta 'kmand

1039
00:46:20,720 --> 00:46:25,740
argumenti, li tkun se let us
fil-fatt tikseb fuq kliem li inti tip,

1040
00:46:25,740 --> 00:46:28,570
fil-pront Teptip,
wara l-isem program tiegħek.

1041
00:46:28,570 --> 00:46:31,430
>> Allura fil-jiem li ġejjin, inti
jista tip xi ħaġa bħal Caesar,

1042
00:46:31,430 --> 00:46:34,950
jew ./caesar numru 13, wara dan.

1043
00:46:34,950 --> 00:46:36,070
Aħna ser tara kif din taħdem.

1044
00:46:36,070 --> 00:46:37,550
Minħabba tabilħaqq, fl
problema stabbiliti tnejn, aħna qed

1045
00:46:37,550 --> 00:46:39,383
ser jintroduċu inti
li ftit xi ħaġa

1046
00:46:39,383 --> 00:46:42,360
reminixxenti tal tal Ralphie
jisfida qabel ta 'kartografija.

1047
00:46:42,360 --> 00:46:43,970
L-arti ta 'scrambling informazzjoni.

1048
00:46:43,970 --> 00:46:46,660
Dan, fil-fatt, huwa ferm
reminixxenti ta 'dak Ralphie għamlet.

1049
00:46:46,660 --> 00:46:51,380
>> Dan huwa eżempju ta 'encryption
algoritmu imsejħa rot13, R-O-T 13.

1050
00:46:51,380 --> 00:46:54,910
Li sempliċiment ifisser dawwar il-
ittri fil-alfabett 13 postijiet.

1051
00:46:54,910 --> 00:46:58,309
U jekk inti tagħmel dan, inti ser tara issa
dak li huwa, forsi, frażi familjari.

1052
00:46:58,309 --> 00:47:01,100
Iżda l-mod aħna qed tmur għall-użu
dan, finalment, huwa aktar ġenerali.

1053
00:47:01,100 --> 00:47:04,390
>> Fl P stabbiliti tnejn, fl-edizzjoni standard,
inti ser timplimenta koppja ta 'ciphers,

1054
00:47:04,390 --> 00:47:06,720
wieħed imsejjaħ Caesar, wieħed imsejjaħ Vigenere.

1055
00:47:06,720 --> 00:47:10,090
Kemm minnhom huma rotazzjonali
ciphers, b'mod li b'xi mod inti

1056
00:47:10,090 --> 00:47:11,826
dawran ittra waħda fi ittra differenti.

1057
00:47:11,826 --> 00:47:12,950
U Caesar huwa super sempliċi.

1058
00:47:12,950 --> 00:47:16,220
Inti żid waħda, inti żid 13,
jew xi numru sa 26.

1059
00:47:16,220 --> 00:47:19,570
Vigenere ma li fuq
bażi ta 'kull ittra.

1060
00:47:19,570 --> 00:47:22,140
Allura Vigenere, kif tkun taf tara
fil-spec, hija aktar sikura.

1061
00:47:22,140 --> 00:47:24,973
>> Iżda fl-aħħar tal-ġurnata liema
inti ser tkun l-implimentazzjoni u P sett tnejn,

1062
00:47:24,973 --> 00:47:29,050
hija li ewlieni li tuża kemm
għall encryption u deċifrar.

1063
00:47:29,050 --> 00:47:32,160
B'referenza għall-proċess ta 'tidwir
test sempliċi, xi messaġġ oriġinali,

1064
00:47:32,160 --> 00:47:34,490
fis-test Ċifra, li
hija xi ħaġa encrypted.

1065
00:47:34,490 --> 00:47:36,220
U mbagħad decrypting mill-ġdid.

1066
00:47:36,220 --> 00:47:38,119
>> Fil-Hacker edizzjoni,
sadanittant, inti ser tkun

1067
00:47:38,119 --> 00:47:40,660
kompitu ma 'xi ħaġa simili
fl-ispirtu, fejn aħna ser jagħtuk

1068
00:47:40,660 --> 00:47:44,610
fajl, minn Linux tipiku, jew
Mac, jew Unix kompjuter imsejħa Etsy

1069
00:47:44,610 --> 00:47:47,800
password, li fih ħaġa sħiħa
mazz ta 'usernames u passwords.

1070
00:47:47,800 --> 00:47:50,932
U dawk passwords għandek kollha
ġew encrypted, jew hashed,

1071
00:47:50,932 --> 00:47:53,140
biex ngħidu hekk, aktar sew
kif tkun taf tara fil-spec.

1072
00:47:53,140 --> 00:47:57,090
>> U l-Hacker edizzjoni se jisfida
inti ma tieħu input bħal dan,

1073
00:47:57,090 --> 00:47:58,800
u qsim il-password.

1074
00:47:58,800 --> 00:48:02,590
Dan huwa, jidhru dak l-
password tal-bniedem fil-fatt kien.

1075
00:48:02,590 --> 00:48:05,570
Minħabba, tabilħaqq, passwords huma
ġeneralment mhux maħżuna fil-ċar,

1076
00:48:05,570 --> 00:48:08,260
u ġeneralment passwords
għandu jkun diffiċli li raden.

1077
00:48:08,260 --> 00:48:09,610
Li mhux spiss il-każ.

1078
00:48:09,610 --> 00:48:12,110
>> U dak li ħsibt aħna'd nagħmlu huwa
tikkonkludi ma ftit minuti

1079
00:48:12,110 --> 00:48:15,160
t'għajn lejn partikolarment
għażla fqira ta 'passwords

1080
00:48:15,160 --> 00:48:17,260
minn film inti tista recall fondly.

1081
00:48:17,260 --> 00:48:18,915
U jekk le, inti għandek kera.

1082
00:48:18,915 --> 00:48:20,070
>> [Daqq ta 'video]

1083
00:48:20,070 --> 00:48:22,320
>> -Helmet, Inti fiend, x'inhu għaddej?

1084
00:48:22,320 --> 00:48:24,240
X'Ser tagħmel biex tifla tiegħi?

1085
00:48:24,240 --> 00:48:28,010
>> -Permit Me li jintroduċu l-
kirurgu tal-plastik żgħażagħ brillanti,

1086
00:48:28,010 --> 00:48:30,010
Doctor Phillip Schlotkin.

1087
00:48:30,010 --> 00:48:35,020
L-akbar raġel impjieg imnieħer fil-
univers kollu u Beverly Hills.

1088
00:48:35,020 --> 00:48:36,140
>> -Your Altezza.

1089
00:48:36,140 --> 00:48:36,820
>> Xogħol -Nose?

1090
00:48:36,820 --> 00:48:37,700
Ma nifhimx.

1091
00:48:37,700 --> 00:48:39,070
Hija diġà kellhom xogħol imnieħer.

1092
00:48:39,070 --> 00:48:40,800
Kien tagħha ħelwa 16 preżenti.

1093
00:48:40,800 --> 00:48:42,590
>> -Nru, Mhuwiex X'taħseb.

1094
00:48:42,590 --> 00:48:44,490
Huwa ħafna, ħafna agħar.

1095
00:48:44,490 --> 00:48:48,160
Jekk inti ma tagħti me-
kombinazzjoni mal-tarka arja,

1096
00:48:48,160 --> 00:48:52,748
tabib Schlotkin se jagħti tiegħek
bint back imnieħer tagħha qodma.

1097
00:48:52,748 --> 00:48:53,748
- [Gasps] Nooooooooooooo.

1098
00:48:53,748 --> 00:48:57,684

1099
00:48:57,684 --> 00:48:59,652
Fejn ma ikollok dan?

1100
00:48:59,652 --> 00:49:00,640
>> -kull Dritt.

1101
00:49:00,640 --> 00:49:02,506
I ser jgħidlek, jien ser jgħidlek.

1102
00:49:02,506 --> 00:49:03,498
>> -Nru, Daddy, ebda.

1103
00:49:03,498 --> 00:49:04,490
Inti ma trid.

1104
00:49:04,490 --> 00:49:06,090
>> -You're Dritt għeżież tiegħi.

1105
00:49:06,090 --> 00:49:07,390
I ser titlef imnieħer ġdida tiegħek.

1106
00:49:07,390 --> 00:49:10,990
Imma jien mhux se jgħidulhom l-
kombinazzjoni x'ikun.

1107
00:49:10,990 --> 00:49:12,450
>> -Very Sew.

1108
00:49:12,450 --> 00:49:14,830
Tabib Schlotkin, do agħar tiegħek.

1109
00:49:14,830 --> 00:49:15,744
>> Divertiment -My.

1110
00:49:15,744 --> 00:49:19,860

1111
00:49:19,860 --> 00:49:20,800
>> -Nru!

1112
00:49:20,800 --> 00:49:22,780
Stenna, stenna.

1113
00:49:22,780 --> 00:49:24,000
I ser jgħidlek.

1114
00:49:24,000 --> 00:49:25,830
I ser jgħidlek.

1115
00:49:25,830 --> 00:49:28,270
>> -I Kien jaf ikun taħdem.

1116
00:49:28,270 --> 00:49:31,390
Kull dritt, tagħtiha lili.

1117
00:49:31,390 --> 00:49:36,220
>> -Il Kombinazzjoni hija waħda.

1118
00:49:36,220 --> 00:49:36,740
>> One.

1119
00:49:36,740 --> 00:49:37,473
>> One.

1120
00:49:37,473 --> 00:49:37,972
-Two.

1121
00:49:37,972 --> 00:49:38,471
-Two.

1122
00:49:38,471 --> 00:49:39,800
-Two.

1123
00:49:39,800 --> 00:49:40,300
-Tliet.

1124
00:49:40,300 --> 00:49:40,800
-Tliet.

1125
00:49:40,800 --> 00:49:41,800
-Tliet.

1126
00:49:41,800 --> 00:49:42,300
-Four.

1127
00:49:42,300 --> 00:49:42,800
-Four.

1128
00:49:42,800 --> 00:49:44,707
-Four.

1129
00:49:44,707 --> 00:49:45,521
-Five.

1130
00:49:45,521 --> 00:49:46,430
-Five.

1131
00:49:46,430 --> 00:49:47,930
-Five.

1132
00:49:47,930 --> 00:49:53,480
-Allura-Kombinazzjoni hija waħda,
tnejn, tlieta, erba ', ħames.

1133
00:49:53,480 --> 00:49:56,140
Dik hija l-kombinazzjoni stupidest
I qatt tisma fil-ħajja tiegħi.

1134
00:49:56,140 --> 00:49:58,640
Dik hija l-tip ta 'ħaġa
idjota jkollha fuq bagalji tiegħu.

1135
00:49:58,640 --> 00:50:00,000
>> -Thank Inti, Altezza tiegħek.

1136
00:50:00,000 --> 00:50:01,340
>> [Clicks REMOTE]

1137
00:50:01,340 --> 00:50:02,450
>> Liema ma inti tagħmel?

1138
00:50:02,450 --> 00:50:03,800
>> -I Mitfija l-ħajt.

1139
00:50:03,800 --> 00:50:05,010
>> -Nru, Inti ma, inti
mitfija l-film kollu.

1140
00:50:05,010 --> 00:50:06,220
>> Ve -I ippressat-buttuna ħażina.

1141
00:50:06,220 --> 00:50:07,064
>> -Well, Erġa 'poġġih fuq!

1142
00:50:07,064 --> 00:50:07,910
Poġġi l-film lura fuq!

1143
00:50:07,910 --> 00:50:08,300
>> -Yes, Sir!

1144
00:50:08,300 --> 00:50:08,799
Iva, sir.

1145
00:50:08,799 --> 00:50:09,660
-Let Ħa mmorru, Arnold.

1146
00:50:09,660 --> 00:50:10,450
Come, Gretchen.

1147
00:50:10,450 --> 00:50:12,533
Of course inti taf I ser
għandek inti kont għal dan.

1148
00:50:12,533 --> 00:50:16,720

1149
00:50:16,720 --> 00:50:17,220
-Well?

1150
00:50:17,220 --> 00:50:17,802
Did taħdem?

1151
00:50:17,802 --> 00:50:18,510
Fejn hi l-king?

1152
00:50:18,510 --> 00:50:20,218
>> -Hija Maħduma, sir, aħna
jkollhom l-kombinazzjoni.

1153
00:50:20,218 --> 00:50:20,740
-Great.

1154
00:50:20,740 --> 00:50:24,810
Issa nistgħu jieħdu kull aħħar nifs
ta 'arja friska minn pjaneta Druidia.

1155
00:50:24,810 --> 00:50:25,890
X'hemm-kombinazzjoni?

1156
00:50:25,890 --> 00:50:28,155
>> One, tnejn, tlieta, erba ', ħames.

1157
00:50:28,155 --> 00:50:29,890
>> One, tnejn, tlieta, erba ', ħames?

1158
00:50:29,890 --> 00:50:30,390
-Yes.

1159
00:50:30,390 --> 00:50:31,110
-li Aqwa.

1160
00:50:31,110 --> 00:50:34,550
Stajt ltqajna l-istess
kombinazzjoni fuq bagalji tiegħi.

1161
00:50:34,550 --> 00:50:37,160
Ipprepara Spaceball 1 għall
tluq immedjat.

1162
00:50:37,160 --> 00:50:38,160
>> -Yes, Sir.

1163
00:50:38,160 --> 00:50:40,745
>> -u Jibdlu l-
kombinazzjoni fuq bagalji tiegħi.

1164
00:50:40,745 --> 00:50:41,578
[GĦELUQ ĦOSS DOOR]

1165
00:50:41,578 --> 00:50:42,064
[Clink TA 'BIBIEN laqtu elmu]

1166
00:50:42,064 --> 00:50:42,550
-Ahh.

1167
00:50:42,550 --> 00:50:43,383
[END daqq ta 'video]

1168
00:50:43,383 --> 00:50:46,700
DAVID J. Malan: Li lilha għall
CS50, aħna ser tara inti ġimgħa d-dieħla.

1169
00:50:46,700 --> 00:50:49,883
Narrator: U issa, Deep
Ħsibijiet, billi Daven Farnham.

1170
00:50:49,883 --> 00:50:53,160

1171
00:50:53,160 --> 00:50:55,860
>> DAVEN FARNHAM: Kodifika fis-C huwa
hekk ħafna aktar diffiċli milli Scratch.

1172
00:50:55,860 --> 00:50:57,320
printf, Scratch kien gidba.

1173
00:50:57,320 --> 00:50:59,930

1174
00:50:59,930 --> 00:51:01,430
>> [Soundbite Rires]

1175
00:51:01,430 --> 00:51:02,486