1
00:00:00,000 --> 00:00:12,610

2
00:00:12,610 --> 00:00:12,900
>> DAVID J. Malan: zote haki.

3
00:00:12,900 --> 00:00:16,790
Hivyo welcome kwanza milele
CS50 postmortem kwa jaribio.

4
00:00:16,790 --> 00:00:18,340
Sisi mawazo tunatarajia tawaza
mila hii mwaka huu.

5
00:00:18,340 --> 00:00:20,960
Na hii itakuwa nafasi
kutembea kwa njia ya

6
00:00:20,960 --> 00:00:22,220
ufumbuzi wa jaribio.

7
00:00:22,220 --> 00:00:26,160
Na tutaweza kuharakisha au kupunguza msingi
juu ya maslahi ya wale hapa.

8
00:00:26,160 --> 00:00:29,730
>> Basi, wewe ni pengine hapa kwa sababu wewe ni
nia ya jinsi unaweza kuwa na au

9
00:00:29,730 --> 00:00:31,170
wanapaswa kuwa alijibu baadhi
ya matatizo haya.

10
00:00:31,170 --> 00:00:33,300
Hivyo kwa nini sio sisi kuangalia
katika sehemu hii ya kwanza?

11
00:00:33,300 --> 00:00:34,450
Hivyo kupata masharti.

12
00:00:34,450 --> 00:00:37,600
Hii alitoa wewe versions tatu tofauti
wa mpango huo alikuwa, hatimaye,

13
00:00:37,600 --> 00:00:39,650
maana ya kupata kamba kutoka kwa mtumiaji.

14
00:00:39,650 --> 00:00:42,530
Kama au alifanya hivyo mara
kushoto na wewe kuamua.

15
00:00:42,530 --> 00:00:45,150
>> Na sisi aliuliza katika Swali 0,
kudhani kwamba toleo 1 ni

16
00:00:45,150 --> 00:00:46,400
ulioandaliwa na kuuawa.

17
00:00:46,400 --> 00:00:48,860
Kwa nini huenda mpango segfault?

18
00:00:48,860 --> 00:00:51,150
Kwa mtazamo wa kwanza, mapendekezo yoyote
kama ni kwa nini?

19
00:00:51,150 --> 00:00:54,012

20
00:00:54,012 --> 00:00:54,489
Yeah.

21
00:00:54,489 --> 00:00:59,260
>> Watazamaji: Kwa hiyo Nakumbuka kuona hii katika
mfano wa awali ya kuangalia

22
00:00:59,260 --> 00:01:05,506
char * s na kuona Scan ya s na
kuona kwa sababu ni pointer, jinsi

23
00:01:05,506 --> 00:01:07,971
gani imekuathiri nini scanned katika?

24
00:01:07,971 --> 00:01:10,940
Je, ni s au anwani ya s?

25
00:01:10,940 --> 00:01:11,180
>> DAVID J. Malan: OK.

26
00:01:11,180 --> 00:01:11,480
Nzuri.

27
00:01:11,480 --> 00:01:14,830
Hivyo hatimaye, chanzo cha tatizo lolote
ni labda kwenda kupunguza

28
00:01:14,830 --> 00:01:16,210
kwa kuwa kutofautiana s.

29
00:01:16,210 --> 00:01:17,280
Na ni kweli kutofautiana.

30
00:01:17,280 --> 00:01:19,900
aina data ya kwamba kutofautiana ni
* Char, ambayo ina maana itakuja

31
00:01:19,900 --> 00:01:22,570
vyenye anwani ya tabia.

32
00:01:22,570 --> 00:01:23,850
Na humo uongo busara.

33
00:01:23,850 --> 00:01:28,330
Ni kwenda vyenye ya barua pepe ya
tabia au, kwa ujumla zaidi,

34
00:01:28,330 --> 00:01:32,110
barua pepe ya tabia ya kwanza katika
kuzuia nzima ya wahusika.

35
00:01:32,110 --> 00:01:36,680
>> Lakini samaki ni kwamba Scan s, lengo katika
maisha, ni kutolewa anwani na kupewa

36
00:01:36,680 --> 00:01:40,960
code format, kama% s, kusoma
kamba ndani ya chunk ya

37
00:01:40,960 --> 00:01:42,330
kumbukumbu katika anwani hiyo.

38
00:01:42,330 --> 00:01:46,040
Lakini kwa sababu hakuna ishara sawa kabla ya
kwamba semicolon ya kwanza

39
00:01:46,040 --> 00:01:49,310
mstari wa kanuni, kwa sababu sisi si kweli
kutenga kumbukumbu yoyote na

40
00:01:49,310 --> 00:01:53,020
malloc, kwa sababu hawakuwa kweli
kutenga safu ya baadhi ukubwa, kila

41
00:01:53,020 --> 00:01:57,620
wewe ni kufanya ni kusoma mtumiaji
keyboard mchango katika baadhi kamili

42
00:01:57,620 --> 00:02:00,490
takataka thamani, ambayo
ni katika s by default.

43
00:02:00,490 --> 00:02:04,480
Hivyo ni tabia mbaya wewe kwenda segfault kama
anwani hiyo si tu hivyo kutokea

44
00:02:04,480 --> 00:02:08,009
kuwa thamani kwamba unaweza,
kwa kweli, kuandika.

45
00:02:08,009 --> 00:02:10,889
Hivyo si mbaya kwa kutenga
kumbukumbu yako huko.

46
00:02:10,889 --> 00:02:13,150
>> Hivyo katika swali 1, sisi aliuliza,
kudhani kwamba toleo la 2 ni

47
00:02:13,150 --> 00:02:14,230
ulioandaliwa na kuuawa.

48
00:02:14,230 --> 00:02:15,900
Kwa nini huenda mpango huu segfault?

49
00:02:15,900 --> 00:02:17,990
Hivyo hii ni moja ya chini buggy.

50
00:02:17,990 --> 00:02:21,470
Na kuna kweli moja tu
Njia ya wazi ambapo unaweza

51
00:02:21,470 --> 00:02:22,810
kusababisha segfault hapa.

52
00:02:22,810 --> 00:02:23,730
Na hii ni ufadhili.

53
00:02:23,730 --> 00:02:28,180
Wakati wowote sisi ni kutumia c katika kumbukumbu, nini
unaweza kufanya kushawishi segfault

54
00:02:28,180 --> 00:02:30,718
na toleo la 2?

55
00:02:30,718 --> 00:02:35,560
>> Watazamaji: Kama matumizi ya pembejeo kwamba katika
kamba kwamba zaidi ya 49

56
00:02:35,560 --> 00:02:35,975
wahusika.

57
00:02:35,975 --> 00:02:37,260
>> DAVID J. Malan: Hasa.

58
00:02:37,260 --> 00:02:41,420
Wakati wowote unaweza kuona kitu fasta urefu
linapokuja suala la safu, yako

59
00:02:41,420 --> 00:02:44,650
rada lazima kwenda mbali kwamba hii inaweza kuwa
matatizo kama wewe si kuangalia

60
00:02:44,650 --> 00:02:45,810
mipaka ya safu.

61
00:02:45,810 --> 00:02:46,650
Na kwamba ni tatizo hapa.

62
00:02:46,650 --> 00:02:47,910
Bado tuko kutumia scanf.

63
00:02:47,910 --> 00:02:52,200
Bado tuko kutumia% s, ambayo ina maana kujaribu
kusoma kamba kutoka kwa mtumiaji.

64
00:02:52,200 --> 00:02:56,300
Hiyo ambayo kwenda kusoma katika s,,
katika hatua hii, ni ufanisi

65
00:02:56,300 --> 00:02:58,570
barua pepe ya chunk ya kumbukumbu
au ni sawa.

66
00:02:58,570 --> 00:03:02,080
Ni jina la safu
ya wahusika wa kumbukumbu.

67
00:03:02,080 --> 00:03:07,610
>> Lakini hasa ni kwamba, kama wewe kusoma string
kwamba zaidi ya wahusika 49, 49

68
00:03:07,610 --> 00:03:10,440
kwa sababu unahitaji nafasi kwa backslash
0, wewe kwenda kufurika

69
00:03:10,440 --> 00:03:11,390
kwamba buffer.

70
00:03:11,390 --> 00:03:16,410
Na unaweza kupata bahati na kuwa na uwezo wa
kuandika tabia ya 51, 52, 53.

71
00:03:16,410 --> 00:03:18,560
Lakini wakati fulani, OS
ni kwenda kusema, no.

72
00:03:18,560 --> 00:03:21,270
Hii dhahiri si kumbukumbu
wewe ni kuruhusiwa kwa kugusa.

73
00:03:21,270 --> 00:03:23,380
Na mpango ni kwenda segfault.

74
00:03:23,380 --> 00:03:26,650
>> Kwa hiyo, kuna, heuristics lazima yoyote
wakati nimepata fasta urefu, una

75
00:03:26,650 --> 00:03:30,150
kuhakikisha wewe ni kuangalia urefu
ya chochote ni wewe ni kujaribu

76
00:03:30,150 --> 00:03:31,090
kusoma ndani yake.

77
00:03:31,090 --> 00:03:35,110
>> Watazamaji: Hivyo kutatua kwamba, unaweza
kuwa na taarifa kuangalia kweli

78
00:03:35,110 --> 00:03:37,140
ni urefu zaidi
zaidi kuliko au chini ya?

79
00:03:37,140 --> 00:03:37,730
>> DAVID J. Malan: Ndiyo.

80
00:03:37,730 --> 00:03:41,706
Wewe tu na hali
kwamba anasema, kama -

81
00:03:41,706 --> 00:03:46,080
au tuseme wewe si lazima kujua
mapema jinsi wahusika wengi

82
00:03:46,080 --> 00:03:49,060
user ni kwenda kwa aina, kwa sababu
una kuku na yai.

83
00:03:49,060 --> 00:03:51,860
Si mpaka umefanya kusoma katika na scanf
unaweza kufikiri ni muda gani.

84
00:03:51,860 --> 00:03:54,500
Lakini katika hatua hiyo, ni kuchelewa mno,
kwa sababu umefanya tayari kusoma katika

85
00:03:54,500 --> 00:03:55,710
baadhi block ya kumbukumbu.

86
00:03:55,710 --> 00:03:59,590
Hivyo kama kando, avoids CS50 maktaba
suala hili kabisa, kukumbuka

87
00:03:59,590 --> 00:04:01,060
kwa kutumia fgetc.

88
00:04:01,060 --> 00:04:05,390
Na wasomaji tabia kwa wakati mmoja,
ncha-toeing pamoja, kujua kwamba wewe

89
00:04:05,390 --> 00:04:08,060
hawezi kufurika tabia kama
kusoma kwa wakati mmoja.

90
00:04:08,060 --> 00:04:11,580
>> samaki ni kwa GetString kukumbuka ni
kwamba tuna mara kwa mara re-size

91
00:04:11,580 --> 00:04:13,590
kwamba chunk ya kumbukumbu, ambayo
ni tu maumivu.

92
00:04:13,590 --> 00:04:15,310
Ni mengi ya mistari ya
code kufanya hivyo.

93
00:04:15,310 --> 00:04:18,779
Hivyo njia nyingine ya itakuwa
kweli matumizi ya binamu, hivyo

94
00:04:18,779 --> 00:04:19,790
kusema, ya scanf.

95
00:04:19,790 --> 00:04:22,820
Kuna lahaja ya mengi ya haya
kazi ambayo kwa kweli kuangalia

96
00:04:22,820 --> 00:04:25,870
urefu wa jinsi wahusika wengi
unaweza kusoma maximally.

97
00:04:25,870 --> 00:04:29,430
Na unaweza bayana, si kusoma
zaidi ya 50 wahusika.

98
00:04:29,430 --> 00:04:34,110
Hivyo kwamba itakuwa njia nyingine ya lakini
chini ya accommodating wa pembejeo kubwa.

99
00:04:34,110 --> 00:04:37,040
>> Hivyo swali 2 anauliza, tuseme toleo kwamba
3 ni ulioandaliwa na kuuawa.

100
00:04:37,040 --> 00:04:39,960
Kwa nini huenda mpango huo segfault?

101
00:04:39,960 --> 00:04:42,650
Hivyo hii ni moja ya kweli sawa
kujibu, hata kama ni

102
00:04:42,650 --> 00:04:43,590
inaonekana kidogo fancier.

103
00:04:43,590 --> 00:04:46,440
Sisi ni kutumia malloc, ambayo anahisi kama
sisi ni kutoa wenyewe chaguzi zaidi.

104
00:04:46,440 --> 00:04:48,030
Na kisha sisi ni kumkomboa kwamba
kumbukumbu mwishoni.

105
00:04:48,030 --> 00:04:49,580
Bado ka 50 tu ya kumbukumbu.

106
00:04:49,580 --> 00:04:53,620
Hivyo tupate bado kujaribu kusoma
katika 51, 52, 1000 bytes.

107
00:04:53,620 --> 00:04:55,830
Ni kwenda segfault kwa
hasa sababu hiyo.

108
00:04:55,830 --> 00:04:57,530
>> Lakini kuna sababu nyingine pia.

109
00:04:57,530 --> 00:05:03,890
Nini kingine unaweza malloc kurudi badala ya
barua pepe ya chunk ya kumbukumbu?

110
00:05:03,890 --> 00:05:04,920
Ni inaweza kurudi null.

111
00:05:04,920 --> 00:05:07,560
Na kwa sababu sisi siyo kuangalia kwa
hivyo, tunaweza kufanya kitu

112
00:05:07,560 --> 00:05:11,350
kijinga kwa sababu nyingine, ambayo ni kwamba
sisi tupate kuwa kuwaambia scanf, kusoma

113
00:05:11,350 --> 00:05:16,050
pembejeo mtumiaji kutoka keyboard
ndani ya eneo 0, AKA null.

114
00:05:16,050 --> 00:05:18,890
Na kwamba, pia, dhahiri
kusababisha segfault.

115
00:05:18,890 --> 00:05:21,590
Hivyo kwa ajili ya jaribio, sisi ingekuwa
wamekubali ama ya wale kama

116
00:05:21,590 --> 00:05:22,740
sababu halali.

117
00:05:22,740 --> 00:05:23,420
Moja ni kufanana.

118
00:05:23,420 --> 00:05:25,720
Moja ni pongezi kidogo zaidi.

119
00:05:25,720 --> 00:05:28,975
>> Mwisho, kwa heshima na mpango wa
matumizi ya kumbukumbu, jinsi ya kufanya toleo la 2 na

120
00:05:28,975 --> 00:05:30,350
version 3 tofauti?

121
00:05:30,350 --> 00:05:35,070
Hivyo kwa nini ni thamani, tuliona
inaonekana kutokuwa na mwisho usambazaji wa iwezekanavyo

122
00:05:35,070 --> 00:05:35,770
majibu ya hii.

123
00:05:35,770 --> 00:05:39,300
Na kati ya majibu ya watu, nini tulikuwa
matumaini kwa, lakini tulikubali nyingine

124
00:05:39,300 --> 00:05:42,250
mambo, na baadhi ya kutaja
ukweli kwamba toleo la 2 ni kwa kutumia

125
00:05:42,250 --> 00:05:44,560
kinachojulikana stack.

126
00:05:44,560 --> 00:05:46,710
Version 3 ni kwa kutumia chungu.

127
00:05:46,710 --> 00:05:50,060
Na functionally, hii si kweli
kufanya mengi yote ya tofauti.

128
00:05:50,060 --> 00:05:54,040
Mwisho wa siku, bado tuko
kupata tu 50 ka ya kumbukumbu.

129
00:05:54,040 --> 00:05:56,640
>> Lakini hiyo ilikuwa moja ya majibu iwezekanavyo
kwamba sisi walikuwa kuangalia.

130
00:05:56,640 --> 00:05:59,730
Lakini utaona, kama wewe kupata Quizzes yako
nyuma kutoka TFS, kwamba sisi alifanya

131
00:05:59,730 --> 00:06:04,330
kukubali majadiliano nyingine ya zao
matumizi tofauti ya kumbukumbu pia.

132
00:06:04,330 --> 00:06:08,600
Lakini stack na chungu ingekuwa
jibu rahisi kwenda pamoja.

133
00:06:08,600 --> 00:06:11,150
Maswali yoyote?

134
00:06:11,150 --> 00:06:12,400
Mimi kukupa Rob.

135
00:06:12,400 --> 00:06:18,360

136
00:06:18,360 --> 00:06:20,210
>> Rob BOWDEN: Hivyo tatizo 4.

137
00:06:20,210 --> 00:06:21,985
Hii ni moja ambapo alikuwa na kujaza
katika idadi ya ka nje ya yote

138
00:06:21,985 --> 00:06:23,460
aina hizi mbalimbali kutumika.

139
00:06:23,460 --> 00:06:24,830
Kitu hivyo kwanza sisi kuona.

140
00:06:24,830 --> 00:06:27,930
Kudhani 32-bit usanifu,
kama hii appliance CS50.

141
00:06:27,930 --> 00:06:33,530
Hivyo moja ya mambo ya msingi kuhusu
32-bit architectures, kwamba inatuambia

142
00:06:33,530 --> 00:06:37,490
hasa jinsi kubwa pointer ni kwenda
kuwa katika usanifu.

143
00:06:37,490 --> 00:06:43,020
>> Hivyo mara moja, tunajua kwamba pointer yoyote
aina ni 32-bits au 4 ka.

144
00:06:43,020 --> 00:06:46,010
Ili kuangalia katika meza hii, a
nodi * ni aina pointer.

145
00:06:46,010 --> 00:06:47,250
Hiyo inaenda kuwa 4 ka.

146
00:06:47,250 --> 00:06:51,640
Struct nodi *, hiyo ni halisi
kufanana na nyota nodi.

147
00:06:51,640 --> 00:06:53,590
Na ili kwenda kuwa 4 ka.

148
00:06:53,590 --> 00:06:58,270
Kamba, hivyo hana kuangalia kama
pointer bado, lakini typedef, a

149
00:06:58,270 --> 00:07:01,590
kamba ni * Char, ambayo
ni ya aina pointer.

150
00:07:01,590 --> 00:07:03,550
Ili kwenda kuwa 4 ka.

151
00:07:03,550 --> 00:07:06,150
>> Basi hao tatu wote ni ka 4.

152
00:07:06,150 --> 00:07:09,350
Sasa, node na mwanafunzi ni
kidogo zaidi ngumu.

153
00:07:09,350 --> 00:07:15,160
Hivyo kuangalia node na mwanafunzi, tunaona
node kama integer na pointer.

154
00:07:15,160 --> 00:07:18,050
Na mwanafunzi ni kuyatumia mbili
ndani yake.

155
00:07:18,050 --> 00:07:23,340
Basi angalau kwa kesi yetu hapa, njia
kwamba sisi kuishia kuhesabu ukubwa wa

156
00:07:23,340 --> 00:07:27,020
struct hii ni kuongeza tu juu ya kila kitu
kwamba ndani ya struct.

157
00:07:27,020 --> 00:07:30,690
>> Hivyo kwa node, tuna integer,
ambayo ni 4 ka.

158
00:07:30,690 --> 00:07:32,830
Tuna pointer, ambayo ni 4 ka.

159
00:07:32,830 --> 00:07:35,820
Na hivyo node moja ni kwenda
kuchukua 8 bytes.

160
00:07:35,820 --> 00:07:39,490
Na vile vile kwa mwanafunzi, tuna
pointer kwamba 4 ka na mwingine

161
00:07:39,490 --> 00:07:40,770
pointer kwamba 4 ka.

162
00:07:40,770 --> 00:07:43,180
Ili kwenda kumaliza
juu ya kuwa 8 bytes.

163
00:07:43,180 --> 00:07:45,480
Hivyo node na mwanafunzi ni 8 bytes.

164
00:07:45,480 --> 00:07:48,950
Na watatu hawa ni wote ka 4.

165
00:07:48,950 --> 00:07:50,240
Maswali juu ya hilo?

166
00:07:50,240 --> 00:07:54,640

167
00:07:54,640 --> 00:07:54,990
Ndiyo.

168
00:07:54,990 --> 00:07:58,413
>> Watazamaji: Je, ni mara 64-bit
usanifu, ingekuwa kwamba

169
00:07:58,413 --> 00:07:59,880
mara mbili wote?

170
00:07:59,880 --> 00:08:01,790
>> Rob BOWDEN: Ingekuwa si
mara mbili wote.

171
00:08:01,790 --> 00:08:05,830
Hivyo 64-bit usanifu, ni mara ya pili,
mabadiliko ambayo kitu ya msingi kwamba

172
00:08:05,830 --> 00:08:08,910
pointer ni sasa 64 bits.

173
00:08:08,910 --> 00:08:09,290
Yeah.

174
00:08:09,290 --> 00:08:10,930
Hivyo pointer ni 8 bytes.

175
00:08:10,930 --> 00:08:15,420
Basi hao waliokuwa 4 ka
ni kwenda kuwa 8 bytes.

176
00:08:15,420 --> 00:08:18,617
mwanafunzi, ambayo ilikuwa kuyatumia mbili,
vizuri, sasa ni kwenda

177
00:08:18,617 --> 00:08:19,800
kuwa 8 ka, 8 bytes.

178
00:08:19,800 --> 00:08:21,980
Ni kwenda kufanya 16 bytes.

179
00:08:21,980 --> 00:08:25,710
>> Lakini node bado ni 4 ka.

180
00:08:25,710 --> 00:08:27,800
Hivyo pointer hii ni kwenda
kuwa 8 bytes.

181
00:08:27,800 --> 00:08:28,930
Hii ni 4 ka.

182
00:08:28,930 --> 00:08:30,870
Hivyo node ni kwenda tu
kuwa ka 12.

183
00:08:30,870 --> 00:08:36,309

184
00:08:36,309 --> 00:08:39,280
Maswali yoyote juu ya kwamba mtu?

185
00:08:39,280 --> 00:08:44,500
Hivyo moja ijayo, hizi ni
Codes hali ya HTTP.

186
00:08:44,500 --> 00:08:48,000
Na alikuwa na kuelezea hali
chini ambayo nguvu hizi

187
00:08:48,000 --> 00:08:49,810
kurudishwa kwa wewe.

188
00:08:49,810 --> 00:08:56,730
tatizo moja kwamba nikasikia baadhi ya wanafunzi
ni kwamba walijaribu kufanya

189
00:08:56,730 --> 00:08:58,950
makosa kuwa tarehe ya mwisho ya mteja.

190
00:08:58,950 --> 00:09:02,320
Hivyo wakati sisi kujaribu kufanya ombi
kwa server, kitu huenda

191
00:09:02,320 --> 00:09:03,820
makosa ya mwisho wetu.

192
00:09:03,820 --> 00:09:07,660
Lakini kwa ujumla, kanuni hizi ni
kuwa akarudi na server.

193
00:09:07,660 --> 00:09:11,720
Hivyo tunataka kufikiri nini kinaendelea
au nia mbaya juu ya server kwamba

194
00:09:11,720 --> 00:09:14,280
husababisha mambo haya kurudishwa.

195
00:09:14,280 --> 00:09:18,670
Hivyo kwa nini nguvu anarudi server
hali ya code 200?

196
00:09:18,670 --> 00:09:19,920
Mawazo yoyote?

197
00:09:19,920 --> 00:09:23,360

198
00:09:23,360 --> 00:09:23,730
>> Yeah.

199
00:09:23,730 --> 00:09:27,850
Hivyo kitu kuhusu mafanikio
ombi akaenda kupitia.

200
00:09:27,850 --> 00:09:30,260
Na wao uko na uwezo wa kurudi
chochote akaomba.

201
00:09:30,260 --> 00:09:32,240
Kwa hiyo kila kitu ilikuwa nzuri.

202
00:09:32,240 --> 00:09:35,662
Nini kuhusu 302 kupatikana?

203
00:09:35,662 --> 00:09:36,618
Yeah.

204
00:09:36,618 --> 00:09:39,008
>> Watazamaji: server mara kuangalia
kwa nini ombi.

205
00:09:39,008 --> 00:09:40,442
Lakini hakuweza kupata hiyo.

206
00:09:40,442 --> 00:09:42,850
Hivyo kuna makosa.

207
00:09:42,850 --> 00:09:47,720
>> Rob BOWDEN: Kwa hiyo server mara
kuangalia kwa nini alitaka.

208
00:09:47,720 --> 00:09:51,682
Hivyo tu kuangalia hapa, 302 kupatikana,
alikuwa na uwezo wa kupata hiyo.

209
00:09:51,682 --> 00:09:53,035
>> Watazamaji: Samahani.

210
00:09:53,035 --> 00:09:54,388
Kupatikana ina maana kwamba alifanya kupata hiyo.

211
00:09:54,388 --> 00:09:55,638
Sorry.

212
00:09:55,638 --> 00:09:58,120

213
00:09:58,120 --> 00:10:00,160
>> Rob BOWDEN: Hivyo 302 found.

214
00:10:00,160 --> 00:10:02,350
server ni uwezo wa kupata
nini alitaka.

215
00:10:02,350 --> 00:10:04,640
>> Watazamaji: Lakini si kuonyesha ni?

216
00:10:04,640 --> 00:10:08,180
>> Rob BOWDEN: Tofauti kati ya
hii 302 na 200 ni kwamba

217
00:10:08,180 --> 00:10:09,280
anajua unataka.

218
00:10:09,280 --> 00:10:12,000
Lakini si hasa ambapo
alitaka kuuliza.

219
00:10:12,000 --> 00:10:14,580
Hivyo 302 ni kuelekeza kawaida.

220
00:10:14,580 --> 00:10:16,510
Hivyo ombi ukurasa.

221
00:10:16,510 --> 00:10:19,590
Ni anajua, oh, nataka
kurudi hili.

222
00:10:19,590 --> 00:10:21,070
Lakini hii ni katika URL tofauti.

223
00:10:21,070 --> 00:10:23,534
Hivyo hey, wewe kweli unataka hii.

224
00:10:23,534 --> 00:10:26,950
>> DAVID J. Malan: Ni kipande kuwa alisema
kwamba tuliyowapeni guys kuelekeza

225
00:10:26,950 --> 00:10:30,830
kazi ambayo kutumika header kazi
kwamba, kwa upande wake, kuchapishwa nje ya eneo,

226
00:10:30,830 --> 00:10:34,110
koloni, na kisha URL ambayo
unataka kukataa user.

227
00:10:34,110 --> 00:10:37,480
Hata kama wewe hawakuona 302
wazi kuna, kwamba ni nini PHP

228
00:10:37,480 --> 00:10:41,550
itakuwa magically kuingiza kama header
akisema nini hasa Rob alisema kuna -

229
00:10:41,550 --> 00:10:41,930
kupatikana.

230
00:10:41,930 --> 00:10:43,180
Lakini nenda hapa badala yake.

231
00:10:43,180 --> 00:10:45,960

232
00:10:45,960 --> 00:10:46,160
>> Rob BOWDEN: OK.

233
00:10:46,160 --> 00:10:47,630
Basi nini kuhusu 403 haramu?

234
00:10:47,630 --> 00:10:52,240

235
00:10:52,240 --> 00:10:57,120
>> Watazamaji: Nadhani ni kwamba server
ni kimsingi akisema kwamba mteja

236
00:10:57,120 --> 00:10:59,970
hawawezi kupata ukurasa wa nyumbani.

237
00:10:59,970 --> 00:11:03,260
>> Rob BOWDEN: Hivyo ndiyo.

238
00:11:03,260 --> 00:11:07,670
Naam, jibu kawaida tulikuwa
wanatarajia ni kitu kama, files

239
00:11:07,670 --> 00:11:08,920
si chmodded ipasavyo.

240
00:11:08,920 --> 00:11:11,590
Kwamba pengine chini ya mazingira gani
waona.

241
00:11:11,590 --> 00:11:18,920
Lakini kuna sababu ya kuwa mteja
wanaweza kuwa katika kosa hapa.

242
00:11:18,920 --> 00:11:20,440
Kweli kuna mwingine code hali -

243
00:11:20,440 --> 00:11:21,210
401.

244
00:11:21,210 --> 00:11:22,820
Basi hizi ni sawa sana.

245
00:11:22,820 --> 00:11:24,590
>> 401 ni ruhusa.

246
00:11:24,590 --> 00:11:26,130
Na 403 ni haramu.

247
00:11:26,130 --> 00:11:31,890
Na hivyo ruhusa wewe peke
kupata kama wewe ni hujaingia rasmi kwenye tovuti

248
00:11:31,890 --> 00:11:34,520
Lakini magogo katika huenda maana
kwamba wewe ni mamlaka.

249
00:11:34,520 --> 00:11:37,930
Lakini kama wewe ni tayari watumiaji katika na
bado hawana ruhusa, basi

250
00:11:37,930 --> 00:11:40,140
unaweza pia kupata haramu.

251
00:11:40,140 --> 00:11:45,320
Hivyo kama wewe ni watumiaji katika na hawana
ruhusa, marufuku ni pia

252
00:11:45,320 --> 00:11:47,164
kitu unaweza kupata.

253
00:11:47,164 --> 00:11:48,900
>> DAVID J. Malan: Na utaratibu na
ambayo matatizo haya ni kawaida

254
00:11:48,900 --> 00:11:53,100
kutatuliwa juu ya server ni
kupitia kile amri?

255
00:11:53,100 --> 00:11:57,700
Chmod, kama ni kweli, ruhusa
suala juu ya faili au directory.

256
00:11:57,700 --> 00:11:59,220
>> Rob BOWDEN: Kisha 404 halikupatikana.

257
00:11:59,220 --> 00:12:03,100

258
00:12:03,100 --> 00:12:03,470
Yeah.

259
00:12:03,470 --> 00:12:10,150
Hivyo tofauti na 302 ambapo ilikuwa si hasa
ambapo wewe ni kuuliza lakini anajua

260
00:12:10,150 --> 00:12:12,710
unataka, hii, ni tu ana
sijui nini unataka.

261
00:12:12,710 --> 00:12:15,648
Na wewe ni si kuomba
kitu halali.

262
00:12:15,648 --> 00:12:18,580

263
00:12:18,580 --> 00:12:22,310
418 mimi nina buli na kisha
500 ndani server.

264
00:12:22,310 --> 00:12:24,870
Hivyo kwa nini huenda unaweza kupata kwamba?

265
00:12:24,870 --> 00:12:26,120
>> Hivyo segfault -

266
00:12:26,120 --> 00:12:28,760

267
00:12:28,760 --> 00:12:30,640
Mimi kwa kweli sijui grading
kiwango kwa hili.

268
00:12:30,640 --> 00:12:34,850
Lakini kama PHP code yako alikuwa na kitu
makosa ndani yake, katika nadharia, inaweza

269
00:12:34,850 --> 00:12:39,650
kweli segfault, katika kesi ambayo, hii
500 ndani server makosa, kitu

270
00:12:39,650 --> 00:12:41,400
ni sawa na server yako
Configuration.

271
00:12:41,400 --> 00:12:44,320
Au kuna syntax makosa
katika PHP code yako.

272
00:12:44,320 --> 00:12:46,095
Au kitu mbaya kinachoendelea.

273
00:12:46,095 --> 00:12:48,320
>> DAVID J. Malan Sisi tulikuwa kuona segfault
kati ya majibu watu wachache ya.

274
00:12:48,320 --> 00:12:49,490
Na kitaalam, inaweza kutokea.

275
00:12:49,490 --> 00:12:53,820
Lakini kwamba itakuwa PHP, mpango
imeandikwa na watu wengine, kwa kweli

276
00:12:53,820 --> 00:12:57,790
segfaulted, ambayo tu kama wale watu
Star up na aliandika buggy code katika

277
00:12:57,790 --> 00:13:00,680
mkalimani yao ingekuwa
PHP yenyewe segfault.

278
00:13:00,680 --> 00:13:06,460
Hivyo hata kama 500 ni kama segfault
katika roho, ni karibu kila mara

279
00:13:06,460 --> 00:13:10,490
matokeo ya faili Configuration suala
na mtandao wa kompyuta yako au, kama Rob alisema,

280
00:13:10,490 --> 00:13:13,200
makosa syntax, kama wewe
hakulifunga quote.

281
00:13:13,200 --> 00:13:16,180
Au wewe waliopotea semicolon mahali fulani.

282
00:13:16,180 --> 00:13:23,677
>> Watazamaji: Hivyo kwa Shuttle pset, mimi
kufikiri wakati mimi alifanya hivyo mara moja mimi clicked

283
00:13:23,677 --> 00:13:26,300
browser, lakini hakuna kilichotokea juu,
kile walichokiita nyeupe ukurasa.

284
00:13:26,300 --> 00:13:28,056
Lakini ilikuwa ni kwa sababu ya maadili.

285
00:13:28,056 --> 00:13:29,440
Nadhani kwamba alikuwa JavaScript, sawa?

286
00:13:29,440 --> 00:13:29,770
>> Rob BOWDEN: Yeah.

287
00:13:29,770 --> 00:13:31,180
>> Watazamaji: Je, makosa ambayo
bado kuja?

288
00:13:31,180 --> 00:13:34,290
>> Rob BOWDEN: Hivyo wewe bila waliopata
kosa hili kwa sababu kila kitu

289
00:13:34,290 --> 00:13:36,930
kwa mtazamo wa mtandao wa kompyuta ya
ilikuwa nzuri kabisa.

290
00:13:36,930 --> 00:13:39,090
Lakini ombi index.html.

291
00:13:39,090 --> 00:13:42,000
Uliomba shuttle.js
na service.js.

292
00:13:42,000 --> 00:13:44,580
Na alikuwa na uwezo wa mafanikio kurudi
ninyi mambo hayo yote -

293
00:13:44,580 --> 00:13:44,980
200.

294
00:13:44,980 --> 00:13:45,680
OK.

295
00:13:45,680 --> 00:13:49,330
Ni wakati tu ya browser yako alijaribu
kutafsiri JavaScript kificho kwamba

296
00:13:49,330 --> 00:13:51,370
ni kama, ngoja, hii si
JavaScript makosa halali.

297
00:13:51,370 --> 00:13:55,720

298
00:13:55,720 --> 00:13:58,210
Maswali yoyote mengine?

299
00:13:58,210 --> 00:14:00,750
Sawa.

300
00:14:00,750 --> 00:14:04,120
>> DAVID J. Malan: Hivyo ijayo
up alikuwa namba 11.

301
00:14:04,120 --> 00:14:07,610
Na 11 ilikuwa scariest
kwa mengi ya watu.

302
00:14:07,610 --> 00:14:14,620

303
00:14:14,620 --> 00:14:18,570
Kwa hiyo, jambo muhimu zaidi kukumbuka hapa
ni kwamba hii ilikuwa kweli, kuhusu

304
00:14:18,570 --> 00:14:19,840
orodha mara mbili wanaohusishwa.

305
00:14:19,840 --> 00:14:23,160
Lakini hii haikuwa sawa na mwaka jana
mara mbili wanaohusishwa orodha tatizo,

306
00:14:23,160 --> 00:14:27,170
ambao hawakuwa kukupa caveat kwamba
orodha inaweza, kwa kweli, kuwa zisizochambuliwa.

307
00:14:27,170 --> 00:14:29,640
>> Hivyo ukweli kwamba orodha mara zisizochambuliwa
na ukweli kwamba neno kwamba alikuwa

308
00:14:29,640 --> 00:14:32,930
mkazo kulikuwa na maana ya kufikisha
kwamba hii ni kweli kurahisisha

309
00:14:32,930 --> 00:14:35,430
ya nini vinginevyo ingekuwa
tatizo changamoto zaidi

310
00:14:35,430 --> 00:14:36,600
na tena moja.

311
00:14:36,600 --> 00:14:40,760
Hivyo ni makosa ya kawaida hapa ni kuwa na kuweka
ufumbuzi wa mwaka jana juu ya mmoja wenu

312
00:14:40,760 --> 00:14:45,580
pager na kisha tu upofu nakala ya kwamba
chini kama jibu, ambayo ni haki

313
00:14:45,580 --> 00:14:48,520
kujibu swali mbalimbali
sawa katika roho.

314
00:14:48,520 --> 00:14:51,340
Lakini mambo ya siri hapa
yalikuwa kama ifuatavyo.

315
00:14:51,340 --> 00:14:55,200
>> Hivyo moja, tuna node alitangaza na
inavyoelezwa katika njia ya kawaida hapa.

316
00:14:55,200 --> 00:14:59,230
Kisha sisi defined orodha ya kuwa ya kimataifa
pointer kuanzishwa kwa null.

317
00:14:59,230 --> 00:15:02,150
Kisha inaonekana, kuna kazi mbili
tuna prototypes kwa hapa, kuingiza

318
00:15:02,150 --> 00:15:03,240
na kuondoa.

319
00:15:03,240 --> 00:15:06,600
Na kisha tuna baadhi ya kanuni sampuli hapa
ya kufanya rundo la insertions.

320
00:15:06,600 --> 00:15:09,930
Na kisha tunakuomba kukamilisha
utekelezaji wa kuingiza chini katika vile

321
00:15:09,930 --> 00:15:14,380
njia ambayo ni kuwekeza n katika orodha
katika wakati mara kwa mara, pia bayana,

322
00:15:14,380 --> 00:15:15,730
hata kama tayari sasa.

323
00:15:15,730 --> 00:15:20,600
>> Hivyo uzuri wa kuwa na uwezo wa kuingiza
katika wakati mara kwa mara ni kwamba ina maana

324
00:15:20,600 --> 00:15:23,060
kwamba una kuingiza
nodi mpya wapi?

325
00:15:23,060 --> 00:15:23,690
Ndani ya mbele.

326
00:15:23,690 --> 00:15:27,760
Hivyo hupunguza, nashiriki, angalau
moja ya matukio ya kwamba kutumika kuhitaji

327
00:15:27,760 --> 00:15:30,520
mistari hata zaidi ya kificho, kama ilivyokuwa
mwaka jana na hata katika darasa wakati sisi

328
00:15:30,520 --> 00:15:34,040
aliyesema kwa njia ya aina hii ya kitu
na binadamu na kwa baadhi

329
00:15:34,040 --> 00:15:35,250
matusi Pseudo code.

330
00:15:35,250 --> 00:15:39,190
Hivyo katika ufumbuzi hapa, hebu ruka juu ya
kwa kuwa tu kuwa na Visual juu ya

331
00:15:39,190 --> 00:15:40,480
screen.

332
00:15:40,480 --> 00:15:42,230
>> Taarifa kwamba sisi ni kufanya yafuatayo.

333
00:15:42,230 --> 00:15:45,140
Na pia taarifa kurahisisha nyingine
ni kwamba hata kama ni

334
00:15:45,140 --> 00:15:48,280
tayari sasa, hivyo hii ina maana hata kama
idadi ni tayari pale, unaweza

335
00:15:48,280 --> 00:15:50,280
tu upofu kuingiza mwingine
nakala yake.

336
00:15:50,280 --> 00:15:52,560
Na kwamba, pia, ilikuwa na maana kuwa
kurahisisha, hivyo kwamba unaweza

337
00:15:52,560 --> 00:15:54,940
kuzingatia, kwa kweli, baadhi ya zaidi
kielimu ya kuvutia sehemu na

338
00:15:54,940 --> 00:15:58,090
baadhi sio tu makosa ya ziada kuangalia
kutokana na muda mdogo.

339
00:15:58,090 --> 00:16:02,880
>> Hivyo katika ufumbuzi huu sampuli, sisi kutenga
pointer juu ya mkono wa kushoto

340
00:16:02,880 --> 00:16:04,510
upande hapa kwa nodi.

341
00:16:04,510 --> 00:16:07,190
Sasa, kutambua kwamba pointer, kama
Rob alisema, ni bits 32 tu.

342
00:16:07,190 --> 00:16:09,060
Na haina kweli yana
anwani mpaka

343
00:16:09,060 --> 00:16:09,970
hawawajui anwani.

344
00:16:09,970 --> 00:16:13,220
Na sisi kufanya hivyo juu ya mkono wa kulia
upande kupitia malloc.

345
00:16:13,220 --> 00:16:16,550
Kama raia mwema, sisi kuangalia kwamba
malloc ni si, kwa kweli, null, ili

346
00:16:16,550 --> 00:16:18,690
sisi si ajali kujenga
segfault hapa.

347
00:16:18,690 --> 00:16:22,840
Na wakati wowote kutumia malloc katika maisha,
lazima kuangalia kwa null, ili

348
00:16:22,840 --> 00:16:24,090
una mdudu hila.

349
00:16:24,090 --> 00:16:28,460
>> Kisha sisi initialize kwamba null na
kumshirikisha n na uliopita na ujao.

350
00:16:28,460 --> 00:16:32,450
Na katika kesi hii hapa, mimi kuanzishwa
uliopita kwa null, kwa sababu hii mpya

351
00:16:32,450 --> 00:16:34,780
node ni kwenda kuwa mpya
mwanzo wa orodha yangu.

352
00:16:34,780 --> 00:16:37,050
Kwa hiyo, kuna kwenda kuwa
kitu mbele yake.

353
00:16:37,050 --> 00:16:42,010
Na mimi nataka kimsingi append
orodha zilizopo node mpya kwa

354
00:16:42,010 --> 00:16:44,700
amekaa karibu sawa na orodha yenyewe.

355
00:16:44,700 --> 00:16:47,120
Lakini mimi si kufanyika bado tu.

356
00:16:47,120 --> 00:16:51,780
Hivyo kama orodha yenyewe tayari kuwepo,
na kulikuwa na node angalau moja

357
00:16:51,780 --> 00:16:57,070
tayari ipo, kama hii ni orodha
hapa na mimi kuingiza nodi mpya hapa, mimi

358
00:16:57,070 --> 00:17:01,840
haja ya kuhakikisha kwamba node wangu wa zamani
anasema nyuma ya node yangu mpya,

359
00:17:01,840 --> 00:17:04,260
kwa sababu hii ni mara ya pili,
orodha mara mbili wanaohusishwa.

360
00:17:04,260 --> 00:17:05,460
>> Hivyo sisi kufanya sanity kuangalia.

361
00:17:05,460 --> 00:17:10,109
Kama orodha ni si null, kama tayari kuna
nodes moja au zaidi huko, basi

362
00:17:10,109 --> 00:17:12,470
kuongeza kwamba nyuma kumbukumbu hivyo kusema.

363
00:17:12,470 --> 00:17:15,420
Na kisha jambo la mwisho sana tunahitaji
kufanya ni kweli update kimataifa

364
00:17:15,420 --> 00:17:20,329
variable orodha yenyewe kwa uhakika
kwa kuwa node mpya.

365
00:17:20,329 --> 00:17:21,790
Yeah.

366
00:17:21,790 --> 00:17:26,579
>> Watazamaji: Katika pointer arrow
[Inaudible] ni sawa na null, je, hiyo

367
00:17:26,579 --> 00:17:30,420
kukabiliana na orodha kwa sababu
orodha ni null?

368
00:17:30,420 --> 00:17:30,596
>> DAVID J. Malan: Nope.

369
00:17:30,596 --> 00:17:34,500
Hiyo ni tu mimi kuwa proactively
makini, kwa kuwa kama hii ni yangu

370
00:17:34,500 --> 00:17:38,730
orodha ya awali pamoja na labda baadhi nodes zaidi
juu ya hapa na mimi nina kuingiza yangu

371
00:17:38,730 --> 00:17:42,380
nodi mpya zaidi ya hapa, kuna kwenda
kuwa kitu zaidi ya hapa.

372
00:17:42,380 --> 00:17:44,720
Na mimi nataka kukamata wazo kwamba
kwa kuweka uliopita kwa

373
00:17:44,720 --> 00:17:47,740
null juu ya node mpya.

374
00:17:47,740 --> 00:17:51,410
Na labda, kama kanuni yangu ni sahihi
na hakuna njia nyingine ya kuingiza

375
00:17:51,410 --> 00:17:54,970
nodes kingine chochote zaidi ya kazi hii,
labda, hata kama orodha tayari ina

376
00:17:54,970 --> 00:18:00,090
nodes moja au zaidi ndani yake, labda
orodha, nodi kwanza, ingekuwa

377
00:18:00,090 --> 00:18:02,750
pointer ya awali ya null yenyewe.

378
00:18:02,750 --> 00:18:03,550
>> Watazamaji: Na kama ifuatavyo-up.

379
00:18:03,550 --> 00:18:08,139
sababu ya kuweka pointer usawa ijayo
orodha ni wewe ni kufanya pointer

380
00:18:08,139 --> 00:18:13,579
kabla ya orodha katika kwamba ni akizungumzia
ijayo, mimi nadhani -

381
00:18:13,579 --> 00:18:14,980
Mimi Don 't -

382
00:18:14,980 --> 00:18:15,450
tu orodha?

383
00:18:15,450 --> 00:18:16,400
>> DAVID J. Malan: Hasa.

384
00:18:16,400 --> 00:18:19,400
Na hivyo hebu kweli kufikiria kesi mbili
hapa kweli, hata kama

385
00:18:19,400 --> 00:18:22,070
ili tutaweza kufikiria yao ni si
sawa kabisa kama code.

386
00:18:22,070 --> 00:18:26,250
Lakini kiwango cha juu, kama hii inawakilisha
kuorodhesha na hii ni 32-bit

387
00:18:26,250 --> 00:18:29,560
pointer, rahisi mazingira ni
kwamba hii ni null by default.

388
00:18:29,560 --> 00:18:33,010
Na nadhani wanataka kuingiza
Idadi ya 50 ilikuwa ni idadi ya kwanza.

389
00:18:33,010 --> 00:18:37,640
Hivyo mimi nina kwenda mbele na kutenga
node, ambayo ni kwenda vyenye

390
00:18:37,640 --> 00:18:38,770
mashamba ya tatu -

391
00:18:38,770 --> 00:18:42,070
n, awali, na wa pili.

392
00:18:42,070 --> 00:18:44,580
>> Mimi naenda kuweka idadi 50
hapa, kwa sababu hii itakuwa n.

393
00:18:44,580 --> 00:18:46,130
Hii itakuwa ijayo.

394
00:18:46,130 --> 00:18:48,530
Na hii itakuwa uliopita.

395
00:18:48,530 --> 00:18:50,910
Na hivyo nini mimi katika kesi hii?

396
00:18:50,910 --> 00:18:53,900
Naam, mimi tumefanya tu line 1 hapa.

397
00:18:53,900 --> 00:18:55,400
Pointer n anapata n.

398
00:18:55,400 --> 00:18:57,740
Mimi kisha akasema, uliopita
lazima kupata null.

399
00:18:57,740 --> 00:18:59,470
Hivyo hii ni kwenda kuwa null.

400
00:18:59,470 --> 00:19:01,365
Kisha mimi nina kwenda kusema ijayo
ni kwenda kupata orodha.

401
00:19:01,365 --> 00:19:05,150
>> Na hii kazi nje tu vizuri.

402
00:19:05,150 --> 00:19:06,500
Hii ni null.

403
00:19:06,500 --> 00:19:10,620
Na hivyo mimi kusema, mpya wa nodi unafanya ijayo
shamba lazima kupata chochote hii ni.

404
00:19:10,620 --> 00:19:12,570
Hivyo kwamba unaweka mwingine null huko.

405
00:19:12,570 --> 00:19:14,510
Na kisha jambo la mwisho
Mimi ni kuangalia hapa.

406
00:19:14,510 --> 00:19:17,870
Kama orodha ni si sawa na null, lakini
ni sawa na null, hivyo sisi ruka kwamba

407
00:19:17,870 --> 00:19:18,470
kabisa.

408
00:19:18,470 --> 00:19:23,520
Na hivyo wote mimi kufanya ijayo ni orodha anapata
pointer, ambayo pictorially matokeo katika

409
00:19:23,520 --> 00:19:25,570
picha kama hiyo.

410
00:19:25,570 --> 00:19:26,620
Hivyo kwamba ni tukio moja.

411
00:19:26,620 --> 00:19:30,490
>> Na moja kwamba walikuwa kuuliza kuhusu
hasa ni hali kama hii,

412
00:19:30,490 --> 00:19:33,190
ambapo tayari tuna orodha moja ya node.

413
00:19:33,190 --> 00:19:36,240
Na kama mimi kwenda nyuma juu katika asili
tatizo kauli, karibu tutaweza

414
00:19:36,240 --> 00:19:39,320
kuingiza kusema ni 34, kwa ajili ya
ajili ya majadiliano.

415
00:19:39,320 --> 00:19:46,210
Hivyo nina kwenda tu conveniently
kuteka kwamba zaidi ya hapa.

416
00:19:46,210 --> 00:19:47,540
Nimekuwa tu malloced.

417
00:19:47,540 --> 00:19:49,310
Hebu kudhani mimi nina kuangalia kwa null.

418
00:19:49,310 --> 00:19:51,870
>> Sasa, mimi nina kwenda initialize
n kuwa 34.

419
00:19:51,870 --> 00:19:53,040
Na hii itakuwa n.

420
00:19:53,040 --> 00:19:54,670
Hii itakuwa ijayo.

421
00:19:54,670 --> 00:19:57,100
Na hii itakuwa uliopita.

422
00:19:57,100 --> 00:19:59,370
Hebu kuhakikisha mimi si
kupata hii nyuma.

423
00:19:59,370 --> 00:20:01,110
Uliopita anakuja kwanza
katika ufafanuzi.

424
00:20:01,110 --> 00:20:03,070
Hebu kurekebisha hii.

425
00:20:03,070 --> 00:20:04,410
Hii ni uliopita.

426
00:20:04,410 --> 00:20:05,780
Hii ni ijayo.

427
00:20:05,780 --> 00:20:08,620
Hata kama hawa ni sawa,
hebu kuitunza thabiti.

428
00:20:08,620 --> 00:20:09,450
>> Uliopita.

429
00:20:09,450 --> 00:20:11,030
Hii ni ijayo.

430
00:20:11,030 --> 00:20:16,310
Hivyo nimekuwa tu malloced note yangu, checked
kwa null, kwa ajili ya 34 ndani ya nodi.

431
00:20:16,310 --> 00:20:17,570
Uliopita anapata null.

432
00:20:17,570 --> 00:20:19,480
Hivyo kwamba anatoa mimi kwamba.

433
00:20:19,480 --> 00:20:21,010
Ijayo anapata orodha.

434
00:20:21,010 --> 00:20:22,370
Hivyo orodha ni hii.

435
00:20:22,370 --> 00:20:26,520
Hivyo hii ni sawa na sasa kama kuchora hii
arrow, ili wao uhakika na moja

436
00:20:26,520 --> 00:20:27,940
katika huo.

437
00:20:27,940 --> 00:20:30,400
Na basi mimi nina kuangalia kama orodha
si sawa na null.

438
00:20:30,400 --> 00:20:31,740
Na si wakati huu.

439
00:20:31,740 --> 00:20:35,580
Basi mimi nina kwenda kufanya orodha
uliopita anapata pointer.

440
00:20:35,580 --> 00:20:39,700
>> Hivyo orodha uliopita anapata PTR.

441
00:20:39,700 --> 00:20:44,300
Hivyo hii ina athari ya kuweka
arrow graphical hapa.

442
00:20:44,300 --> 00:20:46,930
Na kwamba kupata kidogo
WAVY, mistari.

443
00:20:46,930 --> 00:20:50,780
Na kisha, mwisho, mimi update
orodha ya uhakika na pointer.

444
00:20:50,780 --> 00:20:55,560
Hivyo sasa hii anazungumzia guy hii.

445
00:20:55,560 --> 00:20:57,170
Na sasa, hebu kufanya haraka
sanity kuangalia.

446
00:20:57,170 --> 00:20:59,470
>> Hapa ni orodha, ambayo ni
variable kimataifa.

447
00:20:59,470 --> 00:21:02,850
node kwanza ni kweli, 34, kwa sababu
Nafuata mshale.

448
00:21:02,850 --> 00:21:05,210
Na kwamba ni sahihi kwa sababu nataka
kuingiza katika mwanzo wa orodha

449
00:21:05,210 --> 00:21:06,070
wote nodes mpya.

450
00:21:06,070 --> 00:21:08,860
Shamba yake ya pili inaongoza mimi guy hii.

451
00:21:08,860 --> 00:21:10,710
Kama mimi kuendelea, mimi hit ya pili ni null.

452
00:21:10,710 --> 00:21:11,760
Hivyo hakuna orodha zaidi.

453
00:21:11,760 --> 00:21:14,460
Kama mimi hit uliopita, mimi kupata
nyuma ambapo mimi kutarajia.

454
00:21:14,460 --> 00:21:16,435
>> Hivyo bado kuna wachache kuyatumia,
wazi, kwa kuendesha.

455
00:21:16,435 --> 00:21:19,870
Lakini ukweli ni kwamba walikuwa aliiambia ya kufanya
hii kwa wakati mara kwa mara ina maana tu

456
00:21:19,870 --> 00:21:22,910
kuwa na idadi finite ya mambo
wewe ni kuruhusiwa kufanya.

457
00:21:22,910 --> 00:21:24,290
Na ni nini idadi hiyo?

458
00:21:24,290 --> 00:21:25,185
Inaweza kuwa hatua moja.

459
00:21:25,185 --> 00:21:25,700
Inaweza kuwa mbili.

460
00:21:25,700 --> 00:21:26,820
Inaweza kuwa hatua 1,000.

461
00:21:26,820 --> 00:21:30,500
Lakini ni finite, ambayo ina maana huwezi
kuwa aina yoyote ya looping kinachoendelea

462
00:21:30,500 --> 00:21:32,010
hapa, hakuna kujirudia, hakuna matanzi.

463
00:21:32,010 --> 00:21:37,390
Ni tu got kuwa mistari ngumu-coded
ya maadili ya kama sisi na katika sampuli hii.

464
00:21:37,390 --> 00:21:42,330
>> Hivyo tatizo ijayo 12 aliuliza yetu
kukamilisha utekelezaji wa kuondoa

465
00:21:42,330 --> 00:21:46,740
chini katika namna ambayo ni kuondosha
n kutoka katika orodha wakati linear.

466
00:21:46,740 --> 00:21:48,740
Hivyo kuwa zaidi kidogo
wiggle chumba sasa.

467
00:21:48,740 --> 00:21:52,380
Unaweza kudhani kuwa n, kama sasa
katika orodha, atakuwepo

468
00:21:52,380 --> 00:21:53,340
hakuna zaidi ya mara moja.

469
00:21:53,340 --> 00:21:56,770
Na kwamba pia ni maana ya kuwa jaribio makao
kurahisisha dhana, hivyo

470
00:21:56,770 --> 00:21:59,780
kwamba kama wewe kupata idadi 50 mahali fulani
katika orodha, huna pia

471
00:21:59,780 --> 00:22:02,890
kuwa na wasiwasi kuhusu kuendelea
iterate, kuangalia kwa kila iwezekanavyo

472
00:22:02,890 --> 00:22:06,990
nakala ya 50, ambayo ingekuwa tu kukabidhi
katika baadhi ya minutia katika muda mdogo.

473
00:22:06,990 --> 00:22:10,460
>> Hivyo, pamoja na kuondoa, hii mara moja dhahiri
changamoto zaidi na zaidi

474
00:22:10,460 --> 00:22:11,640
code kuandika.

475
00:22:11,640 --> 00:22:14,990
Lakini katika mtazamo wa kwanza, kusema ukweli, inaweza
kuangalia balaa na kama kitu

476
00:22:14,990 --> 00:22:17,060
hakuna njia unaweza kuwa na
kuja na juu ya jaribio.

477
00:22:17,060 --> 00:22:22,450
Lakini kama sisi kuzingatia hatua ya mtu binafsi,
hopefully, itakuwa ghafla

478
00:22:22,450 --> 00:22:26,060
mgomo kwamba kila moja ya haya ya mtu binafsi
hatua hufanya akili wazi

479
00:22:26,060 --> 00:22:27,080
katika retrospect.

480
00:22:27,080 --> 00:22:28,200
Hivyo basi tuangalie.

481
00:22:28,200 --> 00:22:32,570
>> Hivyo kwanza, sisi initialize pointer
kuwa orodha yenyewe.

482
00:22:32,570 --> 00:22:36,040
Kwa maana Mimi nataka wakati linear, kwamba njia
Mimi naenda kuwa na baadhi ya kitanzi.

483
00:22:36,040 --> 00:22:39,730
Na njia ya kawaida iterate juu ya
nodes katika orodha muundo au aina yoyote

484
00:22:39,730 --> 00:22:43,860
muundo wa iteratively ni kuchukua
pointer mbele ya data

485
00:22:43,860 --> 00:22:46,990
muundo na kisha kuanza tu kuongezea
yake na kutembea katika njia yako

486
00:22:46,990 --> 00:22:48,650
kwa njia ya muundo data.

487
00:22:48,650 --> 00:22:50,040
Hivyo nina kwenda kwa kufanya hasa kwamba.

488
00:22:50,040 --> 00:22:54,260
>> Wakati pointer, variable yangu ya muda,
si sawa na null, hebu

489
00:22:54,260 --> 00:22:55,660
kwenda mbele na kuangalia.

490
00:22:55,660 --> 00:22:56,910
Je, mimi kupata bahati?

491
00:22:56,910 --> 00:23:01,740
Ni shamba n katika node mimi nina sasa
kuangalia sawa na

492
00:23:01,740 --> 00:23:03,380
idadi mimi nina kuangalia kwa?

493
00:23:03,380 --> 00:23:05,410
Na kama ni hivyo, hebu kufanya kitu fulani.

494
00:23:05,410 --> 00:23:10,020
Sasa, taarifa hii kama hali
mazingira nzima

495
00:23:10,020 --> 00:23:11,520
mstari wa kanuni zifuatazo.

496
00:23:11,520 --> 00:23:14,610
Hili ni jambo tu mimi huduma ya juu -
kutafuta namba katika swali.

497
00:23:14,610 --> 00:23:18,010
Hivyo hakuna mwingine, ambayo simplifies
mambo conceptually kidogo.

498
00:23:18,010 --> 00:23:22,040
>> Lakini sasa, mimi barabara, na unaweza kuwa
tu barabara hii baada ya kufikiria

499
00:23:22,040 --> 00:23:24,720
ni kupitia kidogo, kuna
kweli kesi mbili hapa.

500
00:23:24,720 --> 00:23:28,060
Moja ni ambapo node ni katika
mwanzo wa orodha, ambayo ni

501
00:23:28,060 --> 00:23:31,040
kidogo annoying, kwa sababu hiyo
kesi maalum, kwa sababu una kukabiliana

502
00:23:31,040 --> 00:23:33,340
na jambo hili, ambayo
ni makosa tu.

503
00:23:33,340 --> 00:23:35,720
Kila mahali pengine katika orodha,
ni kitu kimoja.

504
00:23:35,720 --> 00:23:38,050
Kuna node uliopita na ujao
node, node uliopita, nodi ijayo.

505
00:23:38,050 --> 00:23:40,940
Lakini guy hii ni maalum kidogo
kama yeye ni mwanzoni.

506
00:23:40,940 --> 00:23:48,710
>> Hivyo kama pointer sawa na orodha
yenyewe, hivyo kama nina mwanzoni mwa

507
00:23:48,710 --> 00:23:53,960
orodha na nimeona n, mimi haja
kufanya mambo kadhaa ya.

508
00:23:53,960 --> 00:23:59,230
Moja, mimi haja ya kubadili orodha ya
uhakika na shamba ijayo, 50.

509
00:23:59,230 --> 00:24:01,270
Hivyo tuseme kwamba mimi nina kujaribu
kuondoa 34.

510
00:24:01,270 --> 00:24:03,560
Hivyo guy huu got kwenda
mbali katika muda tu.

511
00:24:03,560 --> 00:24:07,210
>> Hivyo nina kwenda kusema, orodha
anapata pointer ijayo.

512
00:24:07,210 --> 00:24:08,570
Naam, hii ni pointer.

513
00:24:08,570 --> 00:24:10,360
Pili ni akizungumzia zaidi ya hapa.

514
00:24:10,360 --> 00:24:17,470
Hivyo hii ni kubadilisha arrow haki hii
sasa kwa uhakika na guy hii hapa.

515
00:24:17,470 --> 00:24:19,580
Sasa, kumbuka, tuna
variable muda.

516
00:24:19,580 --> 00:24:23,520
Hivyo tuna si yatima nodes yoyote,
kwa sababu mimi pia na guy hii katika wangu

517
00:24:23,520 --> 00:24:25,010
utekelezaji wa kuondoa.

518
00:24:25,010 --> 00:24:29,600
Basi sasa, kama orodha yenyewe ni si null,
Mimi haja ya kurekebisha kitu kidogo.

519
00:24:29,600 --> 00:24:32,690
>> Nahitaji sasa kuhakikisha kwamba arrow hii,
ambayo ni awali akizungumzia

520
00:24:32,690 --> 00:24:36,830
50-34, hii ina got kwenda mbali,
kwa sababu kama mimi nina kujaribu kujikwamua

521
00:24:36,830 --> 00:24:41,910
34, 50 alikuwa bora kudumisha yoyote
aina ya nyuma kumbukumbu yake kama

522
00:24:41,910 --> 00:24:42,820
arrow unahitajika.

523
00:24:42,820 --> 00:24:44,820
Hivyo mimi tu alifanya mstari huu.

524
00:24:44,820 --> 00:24:46,520
Hivyo basi mimi nina kufanyika.

525
00:24:46,520 --> 00:24:48,040
Kesi hiyo ni kweli ni rahisi sana.

526
00:24:48,040 --> 00:24:51,010
Chopping off mkuu wa orodha
ni rahisi.

527
00:24:51,010 --> 00:24:52,980
>> Kwa bahati mbaya, kuna hii
annoying mwingine block.

528
00:24:52,980 --> 00:24:56,170
Basi sasa, nina kuzingatia kesi
ambapo kuna kitu katikati.

529
00:24:56,170 --> 00:24:59,880
Lakini si pia kutisha, ila
kwa syntax kama hii.

530
00:24:59,880 --> 00:25:03,080
Basi, ikiwa mimi nina mwanzoni mwa
orodha, mimi nina mahali fulani katikati.

531
00:25:03,080 --> 00:25:08,160
Na mstari huu hapa ni kusema, mwanzo
katika kila node uko katika.

532
00:25:08,160 --> 00:25:11,210

533
00:25:11,210 --> 00:25:18,550
Kwenda shamba node uliopita ijayo
na uhakika kwamba katika pointer.

534
00:25:18,550 --> 00:25:20,390
>> Hebu kufanya hivyo pictorially.

535
00:25:20,390 --> 00:25:21,640
Hiyo ilikuwa kupata ngumu.

536
00:25:21,640 --> 00:25:30,480

537
00:25:30,480 --> 00:25:37,990
Basi, ikiwa mimi na mashamba ya awali hapa -
hebu kufanya hili - mashamba ya karibu hapa.

538
00:25:37,990 --> 00:25:41,200
Mimi nina kwenda kurahisisha kuyatumia yangu badala
kuliko kuteka rundo zima la

539
00:25:41,200 --> 00:25:45,710
mambo na kurudi crisscrossing
kila mmoja.

540
00:25:45,710 --> 00:25:50,870
Na sasa, hebu tu kusema hii ni 1, 2,
3 kwa ajili ya majadiliano, hata

541
00:25:50,870 --> 00:25:53,410
ingawa kuwa haina kujipanga kwa
tatizo katika swali.

542
00:25:53,410 --> 00:25:55,900
>> Hivyo hapa ni orodha yangu wanaohusishwa.

543
00:25:55,900 --> 00:25:59,300
Mimi ni kujaribu kuondoa mbili katika hii
hasa toleo la hadithi.

544
00:25:59,300 --> 00:26:01,960
Hivyo nimekuwa updated pointer kwa
akizungumzia kwa guy hii.

545
00:26:01,960 --> 00:26:03,315
Hivyo hii ni PTR.

546
00:26:03,315 --> 00:26:04,530
Yeye akizungumzia hapa.

547
00:26:04,530 --> 00:26:07,170
Hii ni orodha, ambayo ipo
kimataifa kama kabla ya.

548
00:26:07,170 --> 00:26:09,200
Na yeye akizungumzia hapa bila kujali.

549
00:26:09,200 --> 00:26:10,800
Na sasa, mimi nina kujaribu kuondoa mbili.

550
00:26:10,800 --> 00:26:13,850
>> Hivyo kama pointer ni akizungumzia hapa, mimi nina
kwenda kufuata, inaonekana,

551
00:26:13,850 --> 00:26:17,110
pointer ya awali, ambayo unaweka yangu saa 1.

552
00:26:17,110 --> 00:26:22,290
Mimi kisha kwenda kusema kwamba ijayo
shamba, ambayo huleta mimi juu ya hii

553
00:26:22,290 --> 00:26:25,410
sanduku hapa, ni kwenda
pointer sawa ijayo.

554
00:26:25,410 --> 00:26:28,400
Hivyo kama pointer hii, ni ijayo.

555
00:26:28,400 --> 00:26:31,840
Hiyo ina maana kwamba mahitaji ya mshale
kwa uhakika na guy hii.

556
00:26:31,840 --> 00:26:35,140
>> Kwa hiyo kile kwamba mstari wa kanuni ana haki
kufanyika ni kidogo juu ya hili.

557
00:26:35,140 --> 00:26:37,500
Na sasa, hii ni kuangalia kama
hatua katika mwelekeo sahihi.

558
00:26:37,500 --> 00:26:41,390
Sisi kimsingi wanataka snip 2 nje
katikati ya 1 na 3.

559
00:26:41,390 --> 00:26:44,400
Hivyo ni mantiki kwamba tunataka
njia pointer hii kuzunguka.

560
00:26:44,400 --> 00:26:50,400
Hivyo line hii ya pili ni kuangalia kama pointer
pili si null, kuna

561
00:26:50,400 --> 00:26:54,200
kweli mtu na haki ya 2,
hiyo ina maana sisi pia kufanya

562
00:26:54,200 --> 00:26:55,850
kidogo snip hapa.

563
00:26:55,850 --> 00:27:00,590
>> Basi, mimi sasa haja ya kufuata pointer hii
na update pointer uliopita juu ya

564
00:27:00,590 --> 00:27:05,410
guy ya kufanya kidogo ya
workaround hapa uhakika hapa.

565
00:27:05,410 --> 00:27:07,100
Na sasa, kuibua hii ni nzuri.

566
00:27:07,100 --> 00:27:11,930
Ni kidogo messy katika kwamba kuna
hakuna mtu akionyesha 2 tena.

567
00:27:11,930 --> 00:27:13,600
2 ni akizungumzia upande wa kushoto.

568
00:27:13,600 --> 00:27:14,980
Na 2 ni akizungumzia haki.

569
00:27:14,980 --> 00:27:17,480
Lakini anaweza kufanya chochote anachotaka, kwa sababu
yeye ni kuhusu kupata huru.

570
00:27:17,480 --> 00:27:19,480
Na haina jambo gani
maadili hayo ni tena.

571
00:27:19,480 --> 00:27:23,040
>> Nini muhimu ni kwamba iliyobaki
guys ni routing juu

572
00:27:23,040 --> 00:27:24,280
na chini yake sasa.

573
00:27:24,280 --> 00:27:25,810
Na kwa kweli, kwamba ni nini sisi kufanya ijayo.

574
00:27:25,810 --> 00:27:29,360
Sisi bure pointer, ambayo ina maana sisi tunasema
mfumo wa uendeshaji, mnakaribishwa

575
00:27:29,360 --> 00:27:30,906
kurudisha hii.

576
00:27:30,906 --> 00:27:34,900
Na kisha mwisho, sisi kurudi.

577
00:27:34,900 --> 00:27:37,220
Mwingine inamuunga, kama sisi
si kurudi bado,

578
00:27:37,220 --> 00:27:38,290
sisi nimepata kuendelea kutafuta.

579
00:27:38,290 --> 00:27:41,485
Hivyo pointer sawa na pointer ijayo tu
maana hoja guy hii hapa.

580
00:27:41,485 --> 00:27:42,600
Hoja guy hii hapa.

581
00:27:42,600 --> 00:27:45,400
Hoja guy hii hapa kama, kwa kweli,
hatukuwa kupata idadi

582
00:27:45,400 --> 00:27:46,960
sisi ni kuangalia kwa bado.

583
00:27:46,960 --> 00:27:49,630
>> Hivyo kusema ukweli, inaonekana kabisa
balaa, nadhani, kwa mara ya kwanza

584
00:27:49,630 --> 00:27:52,180
mtazamo, hasa kama wewe Jihadi
na hii wakati wa jaribio kisha kuona

585
00:27:52,180 --> 00:27:52,850
kitu kama hiki.

586
00:27:52,850 --> 00:27:55,050
Na wewe pat mwenyewe juu ya nyuma.

587
00:27:55,050 --> 00:27:57,080
Naam, hakuna njia mimi naweza kuwa na
kuja na kwamba jaribio.

588
00:27:57,080 --> 00:28:00,470
Lakini napenda wanasema, unaweza kama wewe kuvunja
chini katika hizi mtu binafsi

589
00:28:00,470 --> 00:28:04,400
kesi na kutembea tu kwa njia hiyo
makini, angalau, admittedly, chini ya

590
00:28:04,400 --> 00:28:06,300
mazingira na ukata mkali.

591
00:28:06,300 --> 00:28:09,470
>> Shukrani nyingi, picha alifanya
kila kitu furaha.

592
00:28:09,470 --> 00:28:11,050
Unaweza kuteka hii katika
idadi yoyote ya njia.

593
00:28:11,050 --> 00:28:12,760
Huna kufanya crisscrossing
kitu hapa.

594
00:28:12,760 --> 00:28:14,520
Unaweza kufanya hivyo kwa moja
mistari kama hii.

595
00:28:14,520 --> 00:28:18,790
Lakini kiini cha tatizo hili, katika
ujumla, mara kutambua kwamba

596
00:28:18,790 --> 00:28:22,060
picha katika mwisho inapaswa kuangalia kidogo
kitu kama hiki, kwa sababu

597
00:28:22,060 --> 00:28:25,030
wakati mara kwa mara alisema kuwa kuweka
Jamming na Jamming na Jamming

598
00:28:25,030 --> 00:28:29,900
nodes mpya mwanzoni
ya orodha.

599
00:28:29,900 --> 00:28:31,960
Maswali yoyote?

600
00:28:31,960 --> 00:28:34,565
Pengine changamoto kubwa ya
hakika maswali coding.

601
00:28:34,565 --> 00:28:37,690
>> Watazamaji: Kwa hiyo ni orodha sawa na
kichwa katika mifano uliopita.

602
00:28:37,690 --> 00:28:39,640
>> DAVID J. Malan: Hasa, hasa.

603
00:28:39,640 --> 00:28:43,130
Tu jina mbalimbali kwa
variable kimataifa.

604
00:28:43,130 --> 00:28:44,380
Duniani kote nini?

605
00:28:44,380 --> 00:28:48,880

606
00:28:48,880 --> 00:28:49,730
>> Rob BOWDEN: OK.

607
00:28:49,730 --> 00:28:52,020
Hivyo hii ni moja ambapo
alikuwa na kuandika aya.

608
00:28:52,020 --> 00:28:56,060
Baadhi ya watu aliandika insha
kwa swali hili.

609
00:28:56,060 --> 00:29:00,230
Lakini wewe tu haja ya kutumia haya masharti sita
kuelezea kile kinachotokea wakati

610
00:29:00,230 --> 00:29:02,440
wewe kujaribu kuwasiliana facebook.com.

611
00:29:02,440 --> 00:29:07,930
Hivyo mimi itabidi kuzungumza kupitia mchakato
kutumia maneno haya yote.

612
00:29:07,930 --> 00:29:11,290
Hivyo katika browser yetu, sisi aina facebook.com
na kugonga kuingia.

613
00:29:11,290 --> 00:29:17,280
Kwa hiyo kivinjari yetu kwenda kujenga
HTTP kuomba kwamba ni kwenda kutuma

614
00:29:17,280 --> 00:29:22,220
kupitia baadhi ya mchakato wa Facebook kwa
Facebook kujibu kwetu pamoja na

615
00:29:22,220 --> 00:29:24,450
HTML ya ukurasa wake.

616
00:29:24,450 --> 00:29:28,800
>> Kwa hiyo kile ni utaratibu
ambayo ombi HTTP

617
00:29:28,800 --> 00:29:30,730
kweli anapata Facebook?

618
00:29:30,730 --> 00:29:32,790
Hivyo kwanza, sisi haja ya kutafsiri
Facebook.com.

619
00:29:32,790 --> 00:29:38,780
Hivyo tu kupewa jina la Facebook.com,
ambapo kwa kweli anafanya ombi HTTP

620
00:29:38,780 --> 00:29:39,940
haja ya kwenda?

621
00:29:39,940 --> 00:29:44,120
Kwa hiyo, tunahitaji kutafsiri Facebook.com
kwa anwani ya IP, ambayo kipekee

622
00:29:44,120 --> 00:29:47,620
kubainisha kile mashine sisi kweli
unataka kutuma ombi hili kwa.

623
00:29:47,620 --> 00:29:49,310
Mbali yako ina anwani ya IP.

624
00:29:49,310 --> 00:29:52,240
Kitu chochote na uhusiano na mtandao
anwani ya IP.

625
00:29:52,240 --> 00:29:59,030
>> Hivyo DNS, Domain Jina System, kwamba ni
nini kinaendelea kushughulikia tafsiri

626
00:29:59,030 --> 00:30:03,750
kutoka facebook.com kwa anwani ya IP kwamba
wewe kweli unataka kuwasiliana.

627
00:30:03,750 --> 00:30:08,075
Hivyo sisi kuwasiliana na DNS server na
kusema, ni nini facebook.com?

628
00:30:08,075 --> 00:30:16,560
Ni anasema, oh, ni anwani ya IP 190.212
jambo, jambo, kitu.

629
00:30:16,560 --> 00:30:16,900
Sawa.

630
00:30:16,900 --> 00:30:18,850
Sasa, najua nini mashine
Nataka kuwasiliana.

631
00:30:18,850 --> 00:30:22,360
>> Hivyo basi kutuma maombi yako HTTP
juu ya mashine hiyo.

632
00:30:22,360 --> 00:30:24,140
Hivyo ni jinsi gani kupata mashine ya kwamba?

633
00:30:24,140 --> 00:30:27,200
Naam, ombi inakwenda kutoka
router kwa router bouncing.

634
00:30:27,200 --> 00:30:32,630
Kumbuka mfano katika darasa, ambapo
sisi kweli kuona kwamba njia

635
00:30:32,630 --> 00:30:35,340
pakiti alichukua tulipojaribu
kuwasiliana.

636
00:30:35,340 --> 00:30:38,460
Tuliiona kuruka juu ya Atlantic
Bahari ya wakati mmoja au chochote.

637
00:30:38,460 --> 00:30:42,820
>> Hivyo bandari mrefu mwisho.

638
00:30:42,820 --> 00:30:46,520
Hivyo hii ni sasa kwenye kompyuta yako.

639
00:30:46,520 --> 00:30:49,970
Unaweza kuwa na mambo mbalimbali sasa
kuwasiliana na internet.

640
00:30:49,970 --> 00:30:53,730
Hivyo siwezi kuwa mbio, kusema, Skype.

641
00:30:53,730 --> 00:30:55,670
Nipate brauza ya mtandao wazi.

642
00:30:55,670 --> 00:30:59,010
Nipate kuwa na kitu ambacho
torrenting files.

643
00:30:59,010 --> 00:31:00,880
Hivyo mambo yote haya ni
kuwasiliana na

644
00:31:00,880 --> 00:31:02,600
internet kwa namna fulani.

645
00:31:02,600 --> 00:31:08,070
>> Hivyo wakati kompyuta yako inapata baadhi data
kutoka katika mtandao, jinsi gani

646
00:31:08,070 --> 00:31:10,130
kujua nini maombi kweli
anataka data?

647
00:31:10,130 --> 00:31:12,610
Jinsi gani kujua kama hii hasa
data ni maana ya

648
00:31:12,610 --> 00:31:16,070
torrenting maombi kinyume
mtandao browser?

649
00:31:16,070 --> 00:31:20,980
Hivyo hii ni lengo la bandari katika
yote ya maombi hayo na

650
00:31:20,980 --> 00:31:22,720
alidai bandari kwenye kompyuta yako.

651
00:31:22,720 --> 00:31:27,580
Hivyo web browser yako anasema, hey,
Mimi nina kusikiliza juu ya bandari 1000.

652
00:31:27,580 --> 00:31:32,240
Na torrenting mpango wako ni kusema,
Mimi nina kusikiliza juu ya bandari 3000.

653
00:31:32,240 --> 00:31:34,770
Na Skype anasema, mimi nina kutumia bandari 4000.

654
00:31:34,770 --> 00:31:41,950
>> Hivyo wakati wewe kupata baadhi ya data kwamba ni
kwa moja ya maombi hayo, data

655
00:31:41,950 --> 00:31:45,510
ni alama na ambayo bandari ni kweli
upelekwe pamoja na.

656
00:31:45,510 --> 00:31:47,950
Hivyo hii anasema, oh, mimi ni
kwa bandari 1000.

657
00:31:47,950 --> 00:31:50,950
Mimi najua kisha nahitaji mbele hii
pamoja na kivinjari yangu.

658
00:31:50,950 --> 00:31:56,440
Hivyo sababu ni muhimu hapa
ni kwamba seva mtandao huwa na

659
00:31:56,440 --> 00:31:58,240
kusikiliza juu ya bandari 80.

660
00:31:58,240 --> 00:32:02,420
Hivyo wakati mimi kuwasiliana na Facebook.com, mimi nina
kuwasiliana na baadhi ya mashine.

661
00:32:02,420 --> 00:32:06,390
Lakini mimi haja ya kusema ambayo bandari ya kwamba
mashine nataka kuwasiliana na.

662
00:32:06,390 --> 00:32:09,160
Na vya mtandao huwa na kuwa
kusikiliza kwenye bandari 80.

663
00:32:09,160 --> 00:32:14,010
>> Kama walitaka, hawakuweza kuweka
up hivyo orodha kama juu ya bandari 7000.

664
00:32:14,010 --> 00:32:19,090
Na kisha katika mtandao browser, mimi naweza
manually aina Facebook.com: 7000 kwa

665
00:32:19,090 --> 00:32:24,600
kutuma maombi kwa bandari 7000
ya Picha ya mtandao wa kompyuta.

666
00:32:24,600 --> 00:32:26,820
>> DAVID J. Malan: Na katika kesi hii, hata
ingawa sisi hakuwa na kuhitaji kwamba watu

667
00:32:26,820 --> 00:32:30,000
kutaja hii, katika kesi hii, bandari nini
ingekuwa kweli ombi kwenda?

668
00:32:30,000 --> 00:32:36,630

669
00:32:36,630 --> 00:32:37,880
Jaribu tena.

670
00:32:37,880 --> 00:32:42,810

671
00:32:42,810 --> 00:32:44,300
Hasa.

672
00:32:44,300 --> 00:32:47,960
Si kuangalia kwa kuwa, lakini hila
kuwa kuna hakuna mwisho.

673
00:32:47,960 --> 00:32:51,770
>> Rob BOWDEN: Kwa hiyo HTTPS, kwa vile ni
kusikiliza mahsusi kwa ajili ya

674
00:32:51,770 --> 00:32:55,180
encrypted, ni juu ya bandari 4430.

675
00:32:55,180 --> 00:32:57,680
>> Watazamaji: Na barua pepe ni 25, sawa?

676
00:32:57,680 --> 00:33:00,670
>> DAVID J. Malan: inayotoka
barua pepe, 25, yep.

677
00:33:00,670 --> 00:33:03,760
>> Rob BOWDEN: Mimi si hata kujua zaidi ya
- Yote ya wale wa chini huwa na kuwa

678
00:33:03,760 --> 00:33:06,310
zimehifadhiwa kwa ajili ya mambo.

679
00:33:06,310 --> 00:33:09,260
Nadhani kila kitu chini ya
1024 ni zimehifadhiwa.

680
00:33:09,260 --> 00:33:13,450
>> Watazamaji: Kwa nini kusema
3 ilikuwa ni idadi sahihi?

681
00:33:13,450 --> 00:33:18,820
>> Rob BOWDEN: Kwa sababu katika anwani ya IP,
kuna makundi manne ya tarakimu.

682
00:33:18,820 --> 00:33:21,090
Na wao ni 0-255.

683
00:33:21,090 --> 00:33:28,060
Hivyo 192.168.2.1 ni ya kawaida
ndani ya mtandao anwani ya IP.

684
00:33:28,060 --> 00:33:30,840
Taarifa ya wale wote ni chini ya 255.

685
00:33:30,840 --> 00:33:33,570
Hivyo wakati mimi ilianza na 300, kwamba
hakuweza uwezekano wa kuwa na

686
00:33:33,570 --> 00:33:35,210
imekuwa moja ya idadi.

687
00:33:35,210 --> 00:33:38,170
>> DAVID J. Malan: Lakini hiyo silly kipande cha picha ya
kutoka - ilikuwa ni CSI, ambapo walikuwa

688
00:33:38,170 --> 00:33:39,970
idadi hiyo ilikuwa kubwa mno
kwa anwani ya IP.

689
00:33:39,970 --> 00:33:42,940

690
00:33:42,940 --> 00:33:46,110
>> Rob BOWDEN: maswali yoyote juu ya hili?

691
00:33:46,110 --> 00:33:51,710
moja ijayo, mabadiliko hivyo kamili katika
mada, lakini tuna hii safu PHP kwa

692
00:33:51,710 --> 00:33:53,270
nyumba katika quad.

693
00:33:53,270 --> 00:33:56,360
Na sisi kuwa na orodha unordered.

694
00:33:56,360 --> 00:33:59,550
Na tunataka magazeti nje orodha ya kila kitu
tu zenye jina nyumba.

695
00:33:59,550 --> 00:34:09,090

696
00:34:09,090 --> 00:34:11,870
Hivyo tuna foreach kitanzi.

697
00:34:11,870 --> 00:34:17,540
Basi kumbuka, syntax ni foreach
safu kama bidhaa katika safu.

698
00:34:17,540 --> 00:34:22,360
Hivyo kwa njia ya kila iteration ya kitanzi,
nyumba ni kwenda kuchukua moja ya

699
00:34:22,360 --> 00:34:24,060
maadili ndani ya safu.

700
00:34:24,060 --> 00:34:26,530
>> On kwanza iteration, nyumba
itakuwa Cabot House.

701
00:34:26,530 --> 00:34:30,370
On pili iteration, nyumba mapenzi
kuwa Courier House na kadhalika.

702
00:34:30,370 --> 00:34:34,370
Kwa hiyo kwa kila Quad kama nyumba, sisi ni
tu kwenda na magazeti -

703
00:34:34,370 --> 00:34:37,250
wewe pia inaweza kuwa aliunga mkono -

704
00:34:37,250 --> 00:34:42,199
orodha ya bidhaa na kisha jina nyumba ya
na kisha kufunga orodha item.

705
00:34:42,199 --> 00:34:45,210
braces curly ni hiari hapa.

706
00:34:45,210 --> 00:34:49,480
>> Na kisha sisi pia alisema katika swali
yenyewe, kumbuka karibu

707
00:34:49,480 --> 00:34:50,770
unordered orodha tag.

708
00:34:50,770 --> 00:34:53,949
Kwa hiyo, tunahitaji exit PHP mode
ili kufanya hivyo.

709
00:34:53,949 --> 00:35:00,280
Au sisi inaweza kuwa aliunga mkono
karibu unordered orodha tag.

710
00:35:00,280 --> 00:35:02,380
>> DAVID J. Malan: Pia faini hapa ingekuwa
wamekuwa na matumizi ya zamani shule kwa

711
00:35:02,380 --> 00:35:07,340
kitanzi na $ i = 0 0 na kutumia makosa kwa
kufikiri urefu wa ray.

712
00:35:07,340 --> 00:35:09,240
Kabisa faini pia, tu
kidogo wordier.

713
00:35:09,240 --> 00:35:12,170

714
00:35:12,170 --> 00:35:14,742
>> Watazamaji: Hivyo kama wewe walikuwa wanakwenda
[Inaudible], je, kufanya -

715
00:35:14,742 --> 00:35:16,734
Mimi kusahau kile kitanzi [inaudible] ni.

716
00:35:16,734 --> 00:35:21,380
Je, wewe $ Quad bracket i?

717
00:35:21,380 --> 00:35:21,850
>> DAVID J. Malan: Hasa.

718
00:35:21,850 --> 00:35:23,100
Yeah, hasa.

719
00:35:23,100 --> 00:35:26,650

720
00:35:26,650 --> 00:35:27,900
>> Rob BOWDEN: Kitu kingine?

721
00:35:27,900 --> 00:35:31,350

722
00:35:31,350 --> 00:35:32,010
>> DAVID J. Malan: zote haki.

723
00:35:32,010 --> 00:35:32,300
Biashara awamu ya pili.

724
00:35:32,300 --> 00:35:38,290
Basi, kulikuwa na mashada ya majibu
inawezekana kwa kila moja ya haya.

725
00:35:38,290 --> 00:35:40,510
Sisi kweli tu kuangalia kwa
kitu kulazimisha kwa kichwa na

726
00:35:40,510 --> 00:35:41,100
upande wa chini.

727
00:35:41,100 --> 00:35:44,830
Na namba 16 aliuliza, kuhalalisha watumiaji '
pembejeo mteja upande, kama kwa JavaScript,

728
00:35:44,830 --> 00:35:47,280
badala ya server-upande, kama kwa PHP.

729
00:35:47,280 --> 00:35:49,450
Basi nini suala la mafanikio ya
kufanya mteja upande?

730
00:35:49,450 --> 00:35:53,780
>> Naam, moja ya mambo ya sisi mapendekezo ni
kwamba kupunguza utulivu, kwa sababu wewe

731
00:35:53,780 --> 00:35:56,750
hawana bother kuwasiliana na
server, ambayo inaweza kuchukua chache

732
00:35:56,750 --> 00:36:00,390
milliseconds au hata wanandoa wa sekunde
na kuepuka kuwa na tu

733
00:36:00,390 --> 00:36:04,670
kuhalalisha watumiaji 'pembejeo mteja upande na
kuchochea on-kuwasilisha handler na

734
00:36:04,670 --> 00:36:06,650
tu kuangalia, je, wao aina
kitu kwa ajili ya jina?

735
00:36:06,650 --> 00:36:08,080
Je, wao aina ya kitu
kwa ajili ya barua pepe?

736
00:36:08,080 --> 00:36:10,950
Je, wao kuchagua Dorm kutoka
drop-down menu?

737
00:36:10,950 --> 00:36:14,360
>> Unaweza kutoa maoni yao instantaneous
kutumia kompyuta gigahertz

738
00:36:14,360 --> 00:36:16,770
au chochote na kwamba
kweli juu ya dawati yao.

739
00:36:16,770 --> 00:36:19,310
Hivyo tu user bora
uzoefu kawaida.

740
00:36:19,310 --> 00:36:24,460
Lakini upande wa chini ya kufanya mteja upande
uthibitisho, kama wewe kufanya hivyo bila pia

741
00:36:24,460 --> 00:36:29,860
kufanya server-upande uthibitisho ni kwamba
zaidi mtu yeyote kuja nje ya CS50 anajua

742
00:36:29,860 --> 00:36:33,980
kwamba unaweza tu kutuma data yoyote unataka
kwa server idadi yoyote ya njia.

743
00:36:33,980 --> 00:36:37,030
Kusema ukweli, wengi yoyote browser, unaweza
bonyeza kuzunguka katika mazingira na tu

744
00:36:37,030 --> 00:36:40,110
kuzima JavaScript, ambayo,
Kwa hiyo, afya aina yoyote ya

745
00:36:40,110 --> 00:36:41,080
uthibitisho.

746
00:36:41,080 --> 00:36:44,460
>> Lakini pia wanaweza kukumbuka kwamba hata mimi
alifanya baadhi ya mambo arcane katika darasa kwa kutumia

747
00:36:44,460 --> 00:36:47,790
telnet na kwa kweli kujifanya
kuwa kisakuzi kwa kutuma kupata

748
00:36:47,790 --> 00:36:49,240
maombi ya server.

749
00:36:49,240 --> 00:36:51,030
Na kwamba hakika si
kutumia yoyote JavaScript.

750
00:36:51,030 --> 00:36:53,290
Hiyo mimi tu kuandika amri
katika keyboard.

751
00:36:53,290 --> 00:36:57,410
Hivyo kweli, programu yoyote ndani ya kutosha
faraja na mtandao na HTTP

752
00:36:57,410 --> 00:37:01,690
inaweza kutuma chochote data yeye au yeye anataka
kwa server bila uthibitisho.

753
00:37:01,690 --> 00:37:05,470
Na kama seva yako si pia kuangalia,
hawakuwa nipe jina, ni

754
00:37:05,470 --> 00:37:08,930
hii kwa kweli anwani ya barua pepe halali, alifanya
wao kuchagua Dorm, unaweza kumaliza

755
00:37:08,930 --> 00:37:12,800
up kuingiza bogus au tu tupu data
ndani ya orodha yako, ambayo pengine

756
00:37:12,800 --> 00:37:15,450
si kwenda kuwa jambo zuri kama
walikuwa kuchukua ilikuwa pale.

757
00:37:15,450 --> 00:37:16,770
>> Hivyo hii ni ukweli annoying.

758
00:37:16,770 --> 00:37:19,890
Lakini kwa ujumla, mteja upande
uthibitisho ni kubwa.

759
00:37:19,890 --> 00:37:21,810
Lakini ina maana kazi mara mbili zaidi.

760
00:37:21,810 --> 00:37:25,970
Ingawa kuna kufanya kuwepo mbalimbali
maktaba, JavaScript maktaba kwa

761
00:37:25,970 --> 00:37:28,830
mfano, kwamba kufanya hili sana,
kiasi kidogo ya maumivu ya kichwa.

762
00:37:28,830 --> 00:37:31,940
Na unaweza kutumia tena baadhi ya maadili ya
server-upande, mteja upande.

763
00:37:31,940 --> 00:37:35,980
Lakini kutambua kwamba ni kawaida
kazi ya ziada.

764
00:37:35,980 --> 00:37:36,415
Yeah.

765
00:37:36,415 --> 00:37:37,792
>> Watazamaji: Hivyo kama sisi tu
alisema chini ya salama -

766
00:37:37,792 --> 00:37:39,205
>> DAVID J. Malan: [anacheka]

767
00:37:39,205 --> 00:37:39,680
Ugh.

768
00:37:39,680 --> 00:37:43,105
Wale ni daima vigumu
ndio adjudicate.

769
00:37:43,105 --> 00:37:44,480
>> Rob BOWDEN: Hiyo ingekuwa
yamekubaliwa.

770
00:37:44,480 --> 00:37:44,810
>> DAVID J. Malan: Nini?

771
00:37:44,810 --> 00:37:45,810
>> Rob BOWDEN: Mimi kuundwa tatizo hili.

772
00:37:45,810 --> 00:37:46,735
Kwamba ingekuwa kukubalika.

773
00:37:46,735 --> 00:37:47,220
>> DAVID J. Malan: Yeah.

774
00:37:47,220 --> 00:37:47,830
>> Watazamaji: Cool.

775
00:37:47,830 --> 00:37:51,770
>> Rob BOWDEN: Lakini hatukuwa kukubali
kwa mara ya kwanza moja -

776
00:37:51,770 --> 00:37:53,630
vizuri, nini sisi kuangalia kwa ni
kitu kama huna kwa

777
00:37:53,630 --> 00:37:55,270
kuwasiliana na seva.

778
00:37:55,270 --> 00:37:58,355
Hatukuwa kukubali tu kwa kasi zaidi.

779
00:37:58,355 --> 00:38:00,080
>> Watazamaji: Je kuhusu
si upya ukurasa?

780
00:38:00,080 --> 00:38:00,430
>> Rob BOWDEN: Ndiyo.

781
00:38:00,430 --> 00:38:03,000
Hiyo ilikuwa jibu kukubalika.

782
00:38:03,000 --> 00:38:06,300
>> DAVID J. Malan: kitu chochote ambapo sisi waliona
ilikuwa ni zaidi kuliko hata uwezekano

783
00:38:06,300 --> 00:38:09,780
kwamba alijua nini walikuwa
akisema, ambayo ni mgumu

784
00:38:09,780 --> 00:38:13,500
line kuteka wakati mwingine.

785
00:38:13,500 --> 00:38:16,000
Kutumia orodha wanaohusishwa badala
ya safu kudumisha

786
00:38:16,000 --> 00:38:17,590
yamepangwa orodha ya integers.

787
00:38:17,590 --> 00:38:21,000
Hivyo kichwa sisi mara nyingi wanaelezea na uhusiano
orodha ambayo motisha yao yote

788
00:38:21,000 --> 00:38:22,370
kuanzishwa mara kupata mabadiliko.

789
00:38:22,370 --> 00:38:23,030
Wanaweza kukua.

790
00:38:23,030 --> 00:38:23,950
Wanaweza kuogopa.

791
00:38:23,950 --> 00:38:27,370
Hivyo huna kuwa na kuruka kupitia hoops
kwa kweli kujenga kumbukumbu zaidi

792
00:38:27,370 --> 00:38:28,140
kwa safu.

793
00:38:28,140 --> 00:38:30,310
Au huna tu
kusema, tafadhali, user.

794
00:38:30,310 --> 00:38:31,410
safu ni kujazwa.

795
00:38:31,410 --> 00:38:35,850
Ukuaji hivyo nguvu ya orodha.

796
00:38:35,850 --> 00:38:37,210
upande wa chini ingawa orodha wanaohusishwa?

797
00:38:37,210 --> 00:38:40,916

798
00:38:40,916 --> 00:38:43,356
>> Watazamaji: Ni linear.

799
00:38:43,356 --> 00:38:45,800
Kutafuta kwenye orodha wanaohusishwa ni linear
badala ya nini kuingia ndani

800
00:38:45,800 --> 00:38:46,360
>> DAVID J. Malan: Hasa.

801
00:38:46,360 --> 00:38:50,160
Kutafuta kwenye orodha wanaohusishwa ni linear,
hata kama ni vyema, kwa sababu unaweza

802
00:38:50,160 --> 00:38:53,170
tu kufuata makombo haya mkate, hizi
kuyatumia, kutoka mwanzo wa orodha

803
00:38:53,170 --> 00:38:53,570
hadi mwisho.

804
00:38:53,570 --> 00:38:57,970
Huwezi kujiinua kupata random na
hivyo, tafuta binary, hata kama ni

805
00:38:57,970 --> 00:39:00,740
Iliyopangwa, kwamba unaweza
kufanya na safu.

806
00:39:00,740 --> 00:39:02,390
Na pia kuna gharama nyingine.

807
00:39:02,390 --> 00:39:02,966
Yeah.

808
00:39:02,966 --> 00:39:03,800
>> Watazamaji: Kumbukumbu ufanisi?

809
00:39:03,800 --> 00:39:04,130
>> DAVID J. Malan: Yeah.

810
00:39:04,130 --> 00:39:06,940
Naam, mimi ingekuwa si lazima
kusema ufanisi.

811
00:39:06,940 --> 00:39:10,110
Lakini haina gharama zaidi ya kumbukumbu,
kwa sababu unahitaji bits 32 kwa kila

812
00:39:10,110 --> 00:39:13,400
node kwa pointer ya ziada, katika
angalau kwa orodha moja moja wanaohusishwa.

813
00:39:13,400 --> 00:39:16,660
Sasa, kama wewe tu kuhifadhi integers na
wewe ni kuongeza pointer, kwamba

814
00:39:16,660 --> 00:39:17,830
kweli ni aina ya mashirika yasiyo ya maana.

815
00:39:17,830 --> 00:39:19,340
Ni mara dufu kiasi cha kumbukumbu.

816
00:39:19,340 --> 00:39:22,330
Lakini katika hali halisi, kama wewe ni hifadhi
wanaohusishwa orodha ya structs ambayo inaweza kuwa na

817
00:39:22,330 --> 00:39:25,540
8 ka, 16 ka, hata zaidi
zaidi ya kwamba, labda ni chini

818
00:39:25,540 --> 00:39:26,500
ya gharama ya pembezoni.

819
00:39:26,500 --> 00:39:28,320
Lakini ni gharama hivyo.

820
00:39:28,320 --> 00:39:31,880
Hivyo ama ya wale itakuwa wameweza
imekuwa nzuri kama downsides.

821
00:39:31,880 --> 00:39:32,110
>> 18.

822
00:39:32,110 --> 00:39:36,100
Kutumia PHP badala ya C kuandika
amri ya mstari wa mpango.

823
00:39:36,100 --> 00:39:41,890
Hivyo hapa, ni mara nyingi kasi ya kutumia
lugha kama PHP au Ruby au Python.

824
00:39:41,890 --> 00:39:43,700
Wewe tu haraka kufungua
up mhariri wa maandishi.

825
00:39:43,700 --> 00:39:45,900
Una kazi nyingi zaidi
inapatikana na wewe.

826
00:39:45,900 --> 00:39:49,325
PHP ina kuzama jikoni ya utendaji,
ambapo katika C, wewe

827
00:39:49,325 --> 00:39:50,420
na sana, kidogo sana.

828
00:39:50,420 --> 00:39:53,820
Kwa kweli, guys the kujua njia ngumu
kwamba huna meza hash.

829
00:39:53,820 --> 00:39:55,000
Huwezi kuwa na uhusiano orodha.

830
00:39:55,000 --> 00:39:57,470
Kama unataka hizo, una
kutekeleza nao mwenyewe.

831
00:39:57,470 --> 00:40:00,950
>> Hivyo kichwa moja ya PHP au kweli yoyote
kutafsiriwa lugha ni rapidity

832
00:40:00,950 --> 00:40:02,920
ambayo unaweza kuandika code.

833
00:40:02,920 --> 00:40:06,660
Lakini upande wa chini, tuliona hii wakati mimi
haraka kuchapwa up misspeller

834
00:40:06,660 --> 00:40:11,780
utekelezaji katika hotuba kutumia PHP, ni
kwamba kwa kutumia lugha kutafsiriwa

835
00:40:11,780 --> 00:40:13,570
ni kawaida polepole.

836
00:40:13,570 --> 00:40:18,420
Na tuliona kuwa demonstrably na
kuongezeka kwa wakati kutoka sekunde 0.3 hadi 3

837
00:40:18,420 --> 00:40:24,440
sekunde, kwa sababu ya tafsiri
kwamba kweli hutokea.

838
00:40:24,440 --> 00:40:27,060
>> Kichwa mwingine ilikuwa kwamba
hawana kukusanya.

839
00:40:27,060 --> 00:40:30,130
Hivyo pia kasi ya maendeleo
Kwa bahati mbaya, kwa sababu huna

840
00:40:30,130 --> 00:40:31,360
hatua mbili kwa kuendesha programu.

841
00:40:31,360 --> 00:40:32,140
Wewe tu mmoja.

842
00:40:32,140 --> 00:40:35,260
Na hiyo ilikuwa pretty
kulazimisha pia.

843
00:40:35,260 --> 00:40:38,450
Kutumia SQL database badala ya
File CSV kuhifadhi data.

844
00:40:38,450 --> 00:40:40,230
Hivyo SQL database ni kutumika kwa ajili pset7.

845
00:40:40,230 --> 00:40:42,060
Files CSV hakuwa kutumia kiasi.

846
00:40:42,060 --> 00:40:45,960
Lakini kutumika moja kwa moja katika pset7 kama
vizuri kwa kuzungumza na Yahoo Fedha.

847
00:40:45,960 --> 00:40:49,330
>> Lakini CSV ni kama Excel file lakini
super rahisi, ambapo nguzo ni

848
00:40:49,330 --> 00:40:54,010
tu demarked na koma ndani ya
ya vinginevyo Nakala faili.

849
00:40:54,010 --> 00:40:56,740
Na kutumia SQL database ni
kidogo zaidi ya kulazimisha.

850
00:40:56,740 --> 00:41:00,060
Ni suala la mafanikio, kwa sababu ya kupata mambo
kama kuchagua na kuingiza na kufuta.

851
00:41:00,060 --> 00:41:03,790
Na kupata, labda, bahati kwamba
MySQL na database nyingine, kama

852
00:41:03,790 --> 00:41:07,510
Oracle, kujenga kwa ajili yenu katika kumbukumbu, ambayo
ina maana kuchagua yako pengine ni si

853
00:41:07,510 --> 00:41:09,000
kwenda kuwa juu linear chini.

854
00:41:09,000 --> 00:41:11,300
Ni kweli kwenda kuwa kitu
kama search binary au kitu

855
00:41:11,300 --> 00:41:12,520
sawa katika roho.

856
00:41:12,520 --> 00:41:13,930
Hivyo ni kwa ujumla kwa kasi zaidi.

857
00:41:13,930 --> 00:41:16,040
>> Lakini Upande mwingine ni kwamba
ni zaidi kazi tu.

858
00:41:16,040 --> 00:41:16,730
Ni juhudi zaidi.

859
00:41:16,730 --> 00:41:18,140
Una kuelewa database.

860
00:41:18,140 --> 00:41:18,940
Kuwa na kuweka it up.

861
00:41:18,940 --> 00:41:20,840
Unahitaji server kuendesha
kwamba database juu.

862
00:41:20,840 --> 00:41:22,750
Unahitaji kuelewa
jinsi ya configure.

863
00:41:22,750 --> 00:41:24,930
Basi hizi ni tu hizi
aina ya biashara awamu ya pili.

864
00:41:24,930 --> 00:41:27,860
Wakati file CSV, unaweza
kujenga na gedit.

865
00:41:27,860 --> 00:41:28,770
Na wewe ni vizuri kwenda.

866
00:41:28,770 --> 00:41:31,550
Hakuna utata zaidi ya hapo.

867
00:41:31,550 --> 00:41:34,870
>> Kutumia trie badala ya meza hash
na chaining tofauti na kuhifadhi

868
00:41:34,870 --> 00:41:37,490
kamusi ya maneno kukumbusha
ya pset5.

869
00:41:37,490 --> 00:41:42,480
Hivyo anajaribu kichwa, katika nadharia
angalau, ni nini?

870
00:41:42,480 --> 00:41:46,380
Wakati mara kwa mara, angalau kama wewe ni
hashing juu ya kila mmoja binafsi

871
00:41:46,380 --> 00:41:48,990
barua katika neno, kama wewe
wanaweza kuwa kwa pset5.

872
00:41:48,990 --> 00:41:52,720
Hiyo inaweza kuwa hashes tano, sita
hashes kama kuna tano au sita

873
00:41:52,720 --> 00:41:53,900
barua katika neno.

874
00:41:53,900 --> 00:41:54,580
Na kwamba ni nzuri.

875
00:41:54,580 --> 00:41:56,910
Na kama kuna amefungwa juu ya jinsi ya
muda mrefu maneno yako inaweza kuwa, hiyo ni

876
00:41:56,910 --> 00:41:59,320
wakati kweli asymptotically mara kwa mara.

877
00:41:59,320 --> 00:42:05,180
>> Wakati hash meza na tofauti
chaining, tatizo huko na kwamba

878
00:42:05,180 --> 00:42:09,070
aina gani ya muundo data ni kwamba
utendaji wa algorithms yako kwa kawaida

879
00:42:09,070 --> 00:42:12,700
inategemea idadi ya mambo
tayari katika mfumo wa data.

880
00:42:12,700 --> 00:42:15,660
Na kwamba ni dhahiri kesi na
minyororo, ambapo mambo zaidi ya kuweka

881
00:42:15,660 --> 00:42:18,800
katika meza ya hash, tena wale
minyororo kwenda, ambayo ina maana katika hali mbaya zaidi

882
00:42:18,800 --> 00:42:21,960
kesi, kitu unaweza kuwa na kuangalia kwa
ni njia yote mwishoni mwa moja

883
00:42:21,960 --> 00:42:26,000
minyororo wale, ambayo kwa ufanisi
warithi katika kitu linear.

884
00:42:26,000 --> 00:42:29,450
>> Sasa, katika mazoezi, inaweza kabisa
kuwa kesi hiyo hash meza na

885
00:42:29,450 --> 00:42:32,820
minyororo ni kwa kasi zaidi kuliko sambamba
trie utekelezaji.

886
00:42:32,820 --> 00:42:35,570
Lakini hiyo ni kwa sababu mbalimbali, kati ya
ambayo ni inajaribu kutumia mengi yote ya

887
00:42:35,570 --> 00:42:39,240
kumbukumbu kwamba unaweza, kwa kweli, mambo polepole
chini, kwa sababu huwezi kupata nzuri

888
00:42:39,240 --> 00:42:42,410
faida ya kitu kinachoitwa Caching,
ambapo mambo ambayo ni karibu pamoja

889
00:42:42,410 --> 00:42:45,420
katika kumbukumbu kulipata
mara nyingi kwa haraka zaidi.

890
00:42:45,420 --> 00:42:48,180
Na wakati mwingine unaweza kuja na
mzuri hash kazi.

891
00:42:48,180 --> 00:42:51,060
Hata kama wewe kuwa na kupoteza kidogo ya
kumbukumbu, unaweza, kwa kweli, kuwa na uwezo wa

892
00:42:51,060 --> 00:42:54,430
kupata mambo kwa haraka na si
mbaya kama linearly.

893
00:42:54,430 --> 00:42:58,410
>> Hivyo katika muda mfupi, kulikuwa na si lazima
na yoyote ya haya moja au hata mbili

894
00:42:58,410 --> 00:43:00,050
mambo maalum tulikuwa kutafuta.

895
00:43:00,050 --> 00:43:03,080
Kweli chochote kuvutia
kama kichwa na upande wa chini

896
00:43:03,080 --> 00:43:04,800
ujumla hawakupata macho yetu.

897
00:43:04,800 --> 00:43:11,840
>> Rob BOWDEN: Hivyo kwa kichwa, sisi alifanya
si kukubali juu yake mwenyewe "kasi." Wewe

898
00:43:11,840 --> 00:43:14,540
alikuwa na kusema kitu juu yake.

899
00:43:14,540 --> 00:43:17,910
Hata kama wewe alisema kinadharia kwa kasi,
sisi alijua kwamba aina ya kueleweka

900
00:43:17,910 --> 00:43:19,470
kwamba ni 0 ya 1.

901
00:43:19,470 --> 00:43:22,820
Na hash meza, katika nadharia,
si 0 ya 1.

902
00:43:22,820 --> 00:43:26,550
Kutaja chochote kuhusu Runtime
ujumla got pointi.

903
00:43:26,550 --> 00:43:32,640
Lakini "kasi," zaidi ya ufumbuzi juu ya
bodi kubwa kwamba walikuwa inajaribu walikuwa

904
00:43:32,640 --> 00:43:34,990
lengo polepole zaidi kuliko ufumbuzi
waliokuwa meza hash.

905
00:43:34,990 --> 00:43:37,250
Hivyo kasi katika na yenyewe
ni si kweli kweli.

906
00:43:37,250 --> 00:43:41,550

907
00:43:41,550 --> 00:43:44,380
>> DAVID J. Malan: Dom de dom dom.

908
00:43:44,380 --> 00:43:46,686
Mimi nina pengine ni moja tu kwamba anatambua
kwamba ni jinsi gani kwamba walidhani

909
00:43:46,686 --> 00:43:47,500
itamkwe, sawa?

910
00:43:47,500 --> 00:43:50,400
>> Rob BOWDEN: Mimi nilikuwa na kweli hakuna wazo.

911
00:43:50,400 --> 00:43:51,650
>> DAVID J. Malan: Ni alifanya
maana katika kichwa changu.

912
00:43:51,650 --> 00:43:53,830

913
00:43:53,830 --> 00:43:57,580
>> Rob BOWDEN: Mimi kufanya hivyo moja.

914
00:43:57,580 --> 00:43:58,020
OK.

915
00:43:58,020 --> 00:44:04,243
Hivyo hii ni moja ambapo alikuwa na kuteka
mchoro sawa na wewe nguvu

916
00:44:04,243 --> 00:44:06,040
tumeona katika mitihani ya zamani.

917
00:44:06,040 --> 00:44:12,200
Hivyo basi tu kuangalia wakati huu.

918
00:44:12,200 --> 00:44:18,170
Hivyo kutokana na HTML node, tuna mbili
watoto, kichwa na mwili.

919
00:44:18,170 --> 00:44:20,570
Hivyo sisi tawi - kichwa na mwili.

920
00:44:20,570 --> 00:44:22,280
kichwa ina jina tag.

921
00:44:22,280 --> 00:44:23,710
Hivyo tuna cheo.

922
00:44:23,710 --> 00:44:28,450
>> Sasa, jambo moja mengi ya watu
alisahau ni kwamba nodes haya maandishi ni

923
00:44:28,450 --> 00:44:30,430
mambo ya ndani ya mti huu.

924
00:44:30,430 --> 00:44:36,260
Hivyo hapa sisi kutokea kwa kuteka yao kama ovals
kwa vinavhotenganisha haya

925
00:44:36,260 --> 00:44:37,380
aina ya nodes.

926
00:44:37,380 --> 00:44:41,450
Lakini taarifa pia hapa tuna juu,
katikati, na chini kuishia kuwa

927
00:44:41,450 --> 00:44:42,560
Nakala nodes.

928
00:44:42,560 --> 00:44:46,250
Hivyo kusahau wale ilikuwa kiasi fulani
ya makosa ya kawaida.

929
00:44:46,250 --> 00:44:48,770
>> mwili ana watoto watatu -
haya divs tatu.

930
00:44:48,770 --> 00:44:53,340
Hivyo div, div, div na kisha Nakala
watoto node ya divs hizo.

931
00:44:53,340 --> 00:44:55,900
Hiyo ni pretty kiasi
kwa maswali ambayo.

932
00:44:55,900 --> 00:44:57,860
>> DAVID J. Malan: Na ni thamani kubainisha,
ingawa sisi si kukaa juu ya haya

933
00:44:57,860 --> 00:45:01,040
Maelezo katika wakati sisi kutumia katika
JavaScript, kwamba ili gani, katika

934
00:45:01,040 --> 00:45:02,290
kweli, jambo kitaalam.

935
00:45:02,290 --> 00:45:06,330
Hivyo kama kichwa huja kabla ya mwili katika
HTML, basi ni lazima kuonekana

936
00:45:06,330 --> 00:45:08,860
kushoto wa mwili katika DOM halisi.

937
00:45:08,860 --> 00:45:12,265
Kwamba wake ni, kwa ujumla, tu FYI,
kitu kinachoitwa hati ili, ambapo

938
00:45:12,265 --> 00:45:13,260
haina jambo hilo.

939
00:45:13,260 --> 00:45:17,470
Na kama ungekuwa kutekeleza parser,
mpango huo wasomaji HTML katika jengo

940
00:45:17,470 --> 00:45:20,960
juu ya mti katika kumbukumbu, kwa kuwa waaminifu,
kwamba shirikishi pengine nini

941
00:45:20,960 --> 00:45:24,720
kufanya anyway - juu hadi chini,
kushoto na kulia.

942
00:45:24,720 --> 00:45:26,116
>> Rob BOWDEN: Maswali juu ya hilo?

943
00:45:26,116 --> 00:45:29,080

944
00:45:29,080 --> 00:45:30,000
Anatakiwa kufanya moja ijayo?

945
00:45:30,000 --> 00:45:32,380
>> DAVID J. Malan: Uhakika.

946
00:45:32,380 --> 00:45:33,810
>> Rob BOWDEN: OK.

947
00:45:33,810 --> 00:45:39,320
Hivyo hii ni buffer overrun
mashambulizi swali.

948
00:45:39,320 --> 00:45:43,740
Jambo kuu kutambua hapa ni,
vizuri, jinsi nguvu adui hila

949
00:45:43,740 --> 00:45:46,170
mpango huu katika utekelezaji
holela kanuni?

950
00:45:46,170 --> 00:45:51,860
Hivyo argv1, kwanza mstari amri
hoja ya mpango huu, ambayo inaweza kuwa

951
00:45:51,860 --> 00:45:53,920
kiholela kwa muda mrefu.

952
00:45:53,920 --> 00:45:59,160
Lakini hapa sisi ni kutumia memcpy kwa nakala
argv1, ambayo hapa ni bar.

953
00:45:59,160 --> 00:46:00,165
Sisi ni kupita kama hoja.

954
00:46:00,165 --> 00:46:02,050
Na hivyo ni kuchukua jina bar.

955
00:46:02,050 --> 00:46:08,040
>> Hivyo sisi ni memcpying bar
ndani ya hii c buffer.

956
00:46:08,040 --> 00:46:09,400
Jinsi ka wengi sisi kuiga?

957
00:46:09,400 --> 00:46:14,040
Vizuri hata hivyo wengi ka bar hutokea kwa
kutumia, urefu wa hoja hiyo.

958
00:46:14,040 --> 00:46:17,930
Lakini c ni ka 12 tu kote.

959
00:46:17,930 --> 00:46:22,280
Hivyo kama sisi aina hoja ya mstari amri
kwamba zaidi ya ka 12, sisi ni

960
00:46:22,280 --> 00:46:25,470
kwenda kufurika hii
hasa buffer.

961
00:46:25,470 --> 00:46:31,000
Sasa, jinsi gani adui hila
mpango katika utekelezaji code holela?

962
00:46:31,000 --> 00:46:34,910
>> Ili kukumbuka kwamba hapa
kuu ni wito foo.

963
00:46:34,910 --> 00:46:37,340
Na hivyo basi wito kuu foo.

964
00:46:37,340 --> 00:46:40,408
Hebu kuteka hii.

965
00:46:40,408 --> 00:46:44,720

966
00:46:44,720 --> 00:46:46,990
Hivyo tuna stack yetu.

967
00:46:46,990 --> 00:46:49,090
Na kuu ina sura ya stack
chini.

968
00:46:49,090 --> 00:46:51,860

969
00:46:51,860 --> 00:46:53,250
Katika hatua nyingine, wito kuu foo.

970
00:46:53,250 --> 00:46:55,390
Naam, mara moja, wito kuu foo.

971
00:46:55,390 --> 00:46:57,130
Na hivyo foo anapata mwenyewe stack sura yake.

972
00:46:57,130 --> 00:46:59,650

973
00:46:59,650 --> 00:47:02,220
>> Sasa, wakati fulani, foo
ni kwenda na kurudi.

974
00:47:02,220 --> 00:47:06,810
Basi, akaingia foo anarudi, tunahitaji kujua kwa
nini mstari wa kanuni ndani ya kuu sisi

975
00:47:06,810 --> 00:47:10,610
walikuwa ili kujua ambapo
tunapaswa kuendelea katika kuu.

976
00:47:10,610 --> 00:47:13,100
Tunaweza kuwaita foo kutoka nzima
kundi la maeneo mbalimbali.

977
00:47:13,100 --> 00:47:14,620
Jinsi gani tunajua ambapo kurudi?

978
00:47:14,620 --> 00:47:16,460
Naam, sisi haja ya kuhifadhi kwamba mahali fulani.

979
00:47:16,460 --> 00:47:23,010
>> Hivyo mahali fulani haki hapa, sisi kuhifadhi
ambapo tunapaswa kurudi kwa mara moja

980
00:47:23,010 --> 00:47:24,070
foo anarudi.

981
00:47:24,070 --> 00:47:26,350
Na hii ni kurudi anwani.

982
00:47:26,350 --> 00:47:30,490
Hivyo ni jinsi adui anaweza kuchukua faida
hii ni ukweli kwamba

983
00:47:30,490 --> 00:47:37,550
hii c buffer ni kuhifadhiwa, hebu
kusema, haki hapa ni c.

984
00:47:37,550 --> 00:47:39,690
Hivyo sisi tumepewa ka 12 kwa c.

985
00:47:39,690 --> 00:47:40,540
Hii ni c.

986
00:47:40,540 --> 00:47:43,030
Na hii ni foo ya stack pete.

987
00:47:43,030 --> 00:47:49,970
Hivyo kama malicious mtumiaji inaingia zaidi
ka zaidi ya 12 au kuingia amri

988
00:47:49,970 --> 00:47:54,570
line hoja kwamba zaidi ya 12
wahusika, kisha tunakwenda

989
00:47:54,570 --> 00:47:57,540
kufurika buffer hii.

990
00:47:57,540 --> 00:47:59,910
>> Tunaweza kuendelea.

991
00:47:59,910 --> 00:48:02,220
Na wakati fulani, sisi kwenda mbali
kutosha kwamba sisi kuanza

992
00:48:02,220 --> 00:48:05,120
overwriting anwani hii kurudi.

993
00:48:05,120 --> 00:48:08,310
Hivyo mara moja sisi overwrite kurudi mitaani,
hii ina maana kwamba wakati foo

994
00:48:08,310 --> 00:48:14,220
anarudi, sisi ni kurudi popote
user malicious ni kuwaambia ni kwa na

995
00:48:14,220 --> 00:48:19,490
chochote thamani iliingia, kwa chochote
wahusika user aliingia.

996
00:48:19,490 --> 00:48:24,320
Na hivyo kama malicious user ni kuwa
hasa wajanja, anaweza kuwa na hii

997
00:48:24,320 --> 00:48:29,255
kurudi mahali fulani katika printDef
kazi au mahali fulani katika malloc

998
00:48:29,255 --> 00:48:31,830
kazi, tu mahali popote holela.

999
00:48:31,830 --> 00:48:38,420
>> Lakini hata wajanja zaidi ni nini kama ana
user kurudi hapa.

1000
00:48:38,420 --> 00:48:41,920
Na kisha kuanza utekelezaji
haya kama mstari wa kanuni.

1001
00:48:41,920 --> 00:48:46,610
Hivyo katika hatua hiyo, mtumiaji anaweza kuingia
chochote anachotaka katika mkoa huu.

1002
00:48:46,610 --> 00:48:52,210
Na yeye ana mamlaka kamili
juu ya mpango wako.

1003
00:48:52,210 --> 00:48:53,460
Maswali juu ya hilo?

1004
00:48:53,460 --> 00:48:56,380

1005
00:48:56,380 --> 00:49:00,970
Hivyo swali la pili ni kamili
reimplementation ya foo katika namna

1006
00:49:00,970 --> 00:49:02,620
kwamba ni tena katika mazingira magumu.

1007
00:49:02,620 --> 00:49:03,870
>> Hivyo kuna michache ya njia
unaweza kuwa aliyefanya hivyo.

1008
00:49:03,870 --> 00:49:10,900

1009
00:49:10,900 --> 00:49:13,330
Bado tuna c tu
kuwa ya urefu 12.

1010
00:49:13,330 --> 00:49:16,480
Unaweza kuwa iliyopita hii
kama sehemu ya ufumbuzi wako.

1011
00:49:16,480 --> 00:49:18,930
Sisi pia aliongeza kuangalia kufanya
uhakika bar hakuwa null.

1012
00:49:18,930 --> 00:49:24,460
Ingawa hakuwa na haja ya
kwamba kamili ya mikopo.

1013
00:49:24,460 --> 00:49:27,690
Hivyo sisi ni kuangalia kwanza
kamba urefu wa bar.

1014
00:49:27,690 --> 00:49:31,650
Kama ni zaidi ya 12, basi
si kweli kufanya nakala.

1015
00:49:31,650 --> 00:49:33,010
Hivyo kwamba ni njia mojawapo ya fixing.

1016
00:49:33,010 --> 00:49:36,750
>> Njia nyingine ya fixing ni badala ya
kuwa c tu kuwa na urefu 12, kuwa ni

1017
00:49:36,750 --> 00:49:39,310
kuwa ya urefu strlen (bar).

1018
00:49:39,310 --> 00:49:43,370
Njia nyingine ya fixing ni
kwa kweli kurudi tu.

1019
00:49:43,370 --> 00:49:46,690
Hivyo kama wewe alikuwa tu waliopata kuondoa yote ya
hii, kama alikuwa tu kuchapa wote

1020
00:49:46,690 --> 00:49:51,830
mstari wa kanuni, basi bila ya kuwa na kujipatia
mikopo kamili, tangu kazi hii

1021
00:49:51,830 --> 00:49:54,150
Je, si kweli kukamilisha chochote.

1022
00:49:54,150 --> 00:49:57,650
Ni kuiga amri line
hoja katika baadhi ya safu katika

1023
00:49:57,650 --> 00:49:59,960
ndani stack sura yake.

1024
00:49:59,960 --> 00:50:01,310
Na kisha kitu ni kurudi.

1025
00:50:01,310 --> 00:50:04,020
Na chochote yametimia ni gone.

1026
00:50:04,020 --> 00:50:09,740
Hivyo kurudi pia ilikuwa ya kutosha
njia ya kupata mikopo full.

1027
00:50:09,740 --> 00:50:13,425
>> DAVID J. Malan: Si roho kabisa ya
swali lakini kukubalika kwa

1028
00:50:13,425 --> 00:50:15,580
spec hata hivyo.

1029
00:50:15,580 --> 00:50:18,260
>> Rob BOWDEN: Maswali yoyote ya kwamba?

1030
00:50:18,260 --> 00:50:22,270
jambo moja kwamba angalau
inahitajika kuwa na kuandaa kanuni.

1031
00:50:22,270 --> 00:50:24,810
Hivyo hata kama kitaalam wewe si
mazingira magumu kama kanuni yako haina

1032
00:50:24,810 --> 00:50:29,130
kukusanya, hatukuwa kukubali kwamba.

1033
00:50:29,130 --> 00:50:31,350
Hakuna maswali?

1034
00:50:31,350 --> 00:50:33,320
OK.

1035
00:50:33,320 --> 00:50:34,580
>> DAVID J. Malan: Je, unataka
kusema jina hili?

1036
00:50:34,580 --> 00:50:37,230
>> Rob BOWDEN: Hapana

1037
00:50:37,230 --> 00:50:40,470
>> DAVID J. Malan: Kwa hiyo katika hili, hii
ilikuwa ama habari njema au habari mbaya.

1038
00:50:40,470 --> 00:50:43,870
Hii ni halisi tatizo moja
kama jaribio la kwanza.

1039
00:50:43,870 --> 00:50:46,140
Na ni karibu sawa na
tatizo kama pset1.

1040
00:50:46,140 --> 00:50:49,980
Lakini ilikuwa kwa makusudi rahisi kwa kuwa
piramidi rahisi, moja ambayo inaweza kuwa

1041
00:50:49,980 --> 00:50:52,330
kutatuliwa kwa kidogo
rahisi iteration.

1042
00:50:52,330 --> 00:50:55,680
Na kweli, nini sisi kupata katika
hapa haikuwa hivyo mengi mantiki,

1043
00:50:55,680 --> 00:50:58,100
kwa sababu pengine, na hatua hii, wewe ni
vizuri zaidi kuliko ungekuwa

1044
00:50:58,100 --> 00:51:01,850
katika wiki moja na kwa loops au kwa nini tanzi,
lakini kwa kweli tease mbali kwamba

1045
00:51:01,850 --> 00:51:04,790
wewe ni kidogo vizuri na
dhana kwamba PHP ni si tu juu ya nini

1046
00:51:04,790 --> 00:51:05,290
programu.

1047
00:51:05,290 --> 00:51:07,820
Ni kweli anaweza kutumika kama lugha
kuandika programu line amri.

1048
00:51:07,820 --> 00:51:10,060
>> Na kwa kweli, kwamba ni nini sisi kujaribu
kuteka mawazo yako kwa.

1049
00:51:10,060 --> 00:51:12,060
Hii ni amri ya line PHP mpango.

1050
00:51:12,060 --> 00:51:16,690
Hivyo C code hapa, wakati sahihi
katika C, si sahihi kwa PHP.

1051
00:51:16,690 --> 00:51:17,940
Lakini code kweli ni sawa.

1052
00:51:17,940 --> 00:51:21,720
Kama kulinganisha ufumbuzi kwa Quiz
0 dhidi ya Quiz 1, utapata kwamba

1053
00:51:21,720 --> 00:51:25,630
ni karibu sawa, ila kwa
ishara baadhi ya dola na kwa

1054
00:51:25,630 --> 00:51:27,250
kukosekana kwa ajili ya aina data.

1055
00:51:27,250 --> 00:51:31,720
Hasa, kama sisi kuangalia hapa,
utaona kwamba sisi iterate, katika hii

1056
00:51:31,720 --> 00:51:33,730
kesi, kutoka 1 hadi hadi 7.

1057
00:51:33,730 --> 00:51:34,910
>> Tunaweza wamefanya hivyo 0 index.

1058
00:51:34,910 --> 00:51:37,320
Lakini wakati mwingine, nadhani ni haki ya
rahisi wa akili na kufikiri kuhusu mambo

1059
00:51:37,320 --> 00:51:38,200
1-7.

1060
00:51:38,200 --> 00:51:40,300
Kama unataka kuzuia moja, basi wawili
vitalu, kisha ya tatu, kisha

1061
00:51:40,300 --> 00:51:41,770
dot, dot, nukta saba.

1062
00:51:41,770 --> 00:51:45,960
Sisi j kuwa kuanzishwa kwa 1
na kisha kuhesabu hadi kwenye i.

1063
00:51:45,960 --> 00:51:48,150
Na kila kitu hapa ni
vinginevyo kufanana.

1064
00:51:48,150 --> 00:51:49,790
Lakini anastahili kumbuka ni
michache ya mambo.

1065
00:51:49,790 --> 00:51:53,230
Sisi kukupa mistari hizi mbili, hii kwanza
moja, goofily jina lake kama shebang

1066
00:51:53,230 --> 00:51:54,560
kwa bang mkali.

1067
00:51:54,560 --> 00:51:58,770
Na kwamba tu bayana njia,
folder, ambayo mpango unaweza kuwa na

1068
00:51:58,770 --> 00:52:02,160
iligundua kuwa unataka kutumia
kutafsiri faili hii.

1069
00:52:02,160 --> 00:52:04,710
>> Na kisha line baada ya kwamba,
bila shaka, maana kuingia PHP mode.

1070
00:52:04,710 --> 00:52:07,740
Na line chini sana
maana exit PHP mode.

1071
00:52:07,740 --> 00:52:09,740
Na kazi hii, kwa ujumla, kwa
kutafsiriwa lugha.

1072
00:52:09,740 --> 00:52:14,370
Ni aina ya annoying kama wewe kuandika
mpango katika faili iitwayo foo.php.

1073
00:52:14,370 --> 00:52:17,320
Na kisha watumiaji yako na tu
kumbuka, OK, kuendesha mpango huu, mimi

1074
00:52:17,320 --> 00:52:22,320
kuwa na aina "php nafasi foo.php." Aina
ya annoying kama kitu kingine.

1075
00:52:22,320 --> 00:52:25,270
Na pia inaonyesha kwamba mpango wako
imeandikwa katika PHP, ambayo si wote

1076
00:52:25,270 --> 00:52:27,060
kwamba chenye kwa mtumiaji.

1077
00:52:27,060 --> 00:52:30,100
>> Hivyo unaweza kuondoa php. Kabisa
kukumbuka kutoka hotuba.

1078
00:52:30,100 --> 00:52:35,690
Na unaweza kufanya. / Foo kama
umefanya chmodded ni kwa kufanya hivyo

1079
00:52:35,690 --> 00:52:36,500
kutekelezwa.

1080
00:52:36,500 --> 00:52:39,630
Hivyo chmod a + x foo ingekuwa amefanya hivyo.

1081
00:52:39,630 --> 00:52:41,460
Na kama wewe pia kuongeza shebang hapa.

1082
00:52:41,460 --> 00:52:45,320
Lakini kwa kweli, tatizo ni kupata katika
uchapishaji nje kitu kama hiki.

1083
00:52:45,320 --> 00:52:51,100
No HTML, hakuna C-code hakika,
baadhi tu ya PHP.

1084
00:52:51,100 --> 00:52:54,100
Hivyo Milo kisha akarudi katika tatizo 25.

1085
00:52:54,100 --> 00:52:58,050
Na katika 25, walipewa zifuatazo
mifupa code, ambayo ilikuwa

1086
00:52:58,050 --> 00:52:59,730
pretty rahisi mtandao ukurasa.

1087
00:52:59,730 --> 00:53:04,230
Na sehemu Juicy HTML-busara ilikuwa chini
hapa, ambako tuna ndani ya mwili

1088
00:53:04,230 --> 00:53:09,160
fomu ambayo ina kipekee ID ya pembejeo
ndani ya ambayo ilikuwa pembejeo mbili, moja

1089
00:53:09,160 --> 00:53:11,950
na wazo la jina, mmoja
na wazo ya kifungo.

1090
00:53:11,950 --> 00:53:14,240
>> ya kwanza ilikuwa ya aina ya maandishi,
pili ya aina kuwasilisha.

1091
00:53:14,240 --> 00:53:16,930
Na hivyo tuliyowapeni, kwa kweli, zaidi
viungo kuliko unahitajika, ili tu

1092
00:53:16,930 --> 00:53:19,230
nyie na chaguzi na ambayo
kutatua tatizo hili.

1093
00:53:19,230 --> 00:53:21,130
Huwezi madhubuti haja
yote ya vitambulisho haya.

1094
00:53:21,130 --> 00:53:23,580
Lakini utapata kutatua
ni kwa njia tofauti.

1095
00:53:23,580 --> 00:53:27,050
Na hadi saa ya juu, taarifa kwamba
Lengo lilikuwa na kusababisha

1096
00:53:27,050 --> 00:53:27,960
dirisha kama hii -

1097
00:53:27,960 --> 00:53:28,780
Hello, Milo! -

1098
00:53:28,780 --> 00:53:31,270
pop up katika browser kutumia
super rahisi, kama

1099
00:53:31,270 --> 00:53:33,190
si mbaya, tahadhari kazi.

1100
00:53:33,190 --> 00:53:37,480
Na hivyo, hatimaye, hii majipu chini
conceptually kwa namna fulani kusikiliza kwa

1101
00:53:37,480 --> 00:53:41,290
maoni ya aina mteja upande
, Si server-upande, kwa namna fulani

1102
00:53:41,290 --> 00:53:45,640
kukabiliana na kwamba kuwasilishwa kwa
grabbing thamani kwamba mtumiaji typed

1103
00:53:45,640 --> 00:53:50,120
katika shamba jina, na kisha
kuonyesha ni katika mwili wa tahadhari.

1104
00:53:50,120 --> 00:53:53,460
>> Hivyo njia moja unaweza kufanya hivyo ni kwa
jQuery, ambayo inaonekana kidogo

1105
00:53:53,460 --> 00:53:56,880
syntactically kutatanisha mara ya kwanza.

1106
00:53:56,880 --> 00:54:00,760
Unaweza kufanya hivyo na safi DOM code -
document.getelement na ID.

1107
00:54:00,760 --> 00:54:02,530
Lakini hebu tuangalie toleo hili.

1108
00:54:02,530 --> 00:54:05,110
Mimi kuwa wanandoa wa muhimu
mistari ya kwanza.

1109
00:54:05,110 --> 00:54:09,460
Hivyo moja, tuna line hii, ambayo ni
kufanana na nini unaweza kuwa na kuonekana

1110
00:54:09,460 --> 00:54:13,830
katika, naamini, form2.html
kutoka darasa katika wiki 9.

1111
00:54:13,830 --> 00:54:16,960
Na hii ni kusema tu, kutekeleza
code zifuatazo wakati

1112
00:54:16,960 --> 00:54:18,430
hati ni tayari.

1113
00:54:18,430 --> 00:54:21,770
Hii kuwa muhimu tu kwa sababu
Kurasa HTML ni kusoma juu kwa

1114
00:54:21,770 --> 00:54:23,280
chini, kushoto na kulia.

1115
00:54:23,280 --> 00:54:27,910
>> Kwa hiyo, kama wewe kujaribu kufanya
kitu katika kanuni up hapa kwa baadhi DOM

1116
00:54:27,910 --> 00:54:31,560
hiki, baadhi ya tag HTML, hiyo ni chini
hapa, wewe kufanya ni mapema mno,

1117
00:54:31,560 --> 00:54:34,220
kwa sababu hii ina hata
imekuwa kusoma katika kumbukumbu.

1118
00:54:34,220 --> 00:54:37,740
Hivyo kwa kusema document.ready hii
line, sisi ni kusema,

1119
00:54:37,740 --> 00:54:39,040
hapa ni baadhi ya kanuni, browser.

1120
00:54:39,040 --> 00:54:42,440
Lakini si kutekeleza hii mpaka zima
hati ni tayari, kwamba ni DOM

1121
00:54:42,440 --> 00:54:44,320
mti ipo katika kumbukumbu.

1122
00:54:44,320 --> 00:54:47,110
Hii ni moja ya kidogo zaidi
moja kwa moja, kama syntactically a

1123
00:54:47,110 --> 00:54:51,890
tofauti kidogo, ambapo mimi kusema, kunyakua
Hiki HTML ambao kipekee

1124
00:54:51,890 --> 00:54:53,560
kitambulisho ni pembejeo.

1125
00:54:53,560 --> 00:54:56,220
Hiyo ni nini tag hash
inaashiria, ID ya kipekee.

1126
00:54:56,220 --> 00:54:58,070
Na kisha mimi nina wito. Kuwasilisha.

1127
00:54:58,070 --> 00:55:01,660
>> Hivyo. Kuwasilisha hapa ni kazi, vinginevyo
inajulikana kama njia, hiyo ni

1128
00:55:01,660 --> 00:55:05,850
ndani ya kitu juu ya mkono wa kushoto
upande huko kwamba sikuwa kuonyesha.

1129
00:55:05,850 --> 00:55:08,990
Hivyo kama unadhani wa pembejeo kama kitu
katika kumbukumbu - na kwa kweli ni.

1130
00:55:08,990 --> 00:55:10,440
Ni node katika mti -

1131
00:55:10,440 --> 00:55:16,580
. Kuwasilisha njia wakati fomu hii kwa
ID hii ni in, kutekeleza

1132
00:55:16,580 --> 00:55:17,700
code zifuatazo.

1133
00:55:17,700 --> 00:55:20,290
Mimi sijali nini jina la
kazi ni mimi nina utekelezaji.

1134
00:55:20,290 --> 00:55:23,760
Hivyo hapa mimi nina kutumia, kama kabla, nini
aitwaye lambda kazi au

1135
00:55:23,760 --> 00:55:24,720
bila majina kazi.

1136
00:55:24,720 --> 00:55:27,640
Siyo wakati wote kielimu
mengine ya kuvutia kuliko hana jina,

1137
00:55:27,640 --> 00:55:30,220
ambayo ni mzuri kama wewe ni tu
milele kwenda kuiita mara moja.

1138
00:55:30,220 --> 00:55:34,490
Na ndani kuna Mimi kwa kweli kushughulikia
kuwasilisha fomu.

1139
00:55:34,490 --> 00:55:36,810
Mimi kwanza kutangaza variable
aitwaye thamani.

1140
00:55:36,810 --> 00:55:40,610
Na kisha ni nini athari za hii
yalionyesha sehemu hapa sasa?

1141
00:55:40,610 --> 00:55:44,755
Je, hiyo kufanya katika
kiwango cha juu kwa ajili yangu?

1142
00:55:44,755 --> 00:55:48,539
>> Watazamaji: Ni anapata thamani kwamba
user hakuwa katika HTML chini.

1143
00:55:48,539 --> 00:55:50,920
Ni anapata kwamba ID na kisha
hupata thamani yake.

1144
00:55:50,920 --> 00:55:51,590
>> DAVID J. Malan: Hasa.

1145
00:55:51,590 --> 00:55:54,300
Ni grabs node, ambao kipekee
kitambulisho ni jina.

1146
00:55:54,300 --> 00:55:56,900
Anapata thamani humo, ambayo
ni, labda, nini mtumiaji

1147
00:55:56,900 --> 00:55:58,190
typed yeye au yeye mwenyewe.

1148
00:55:58,190 --> 00:56:01,020
Na kisha maduka kwamba katika
variable kuitwa thamani.

1149
00:56:01,020 --> 00:56:03,720
Kama kando, unaweza kuwa na pia
jambo hili tofauti kidogo.

1150
00:56:03,720 --> 00:56:09,250
Kabisa kukubalika kwa kufanya kitu
thamani uongo var anapata

1151
00:56:09,250 --> 00:56:10,500
document.getElementById.

1152
00:56:10,500 --> 00:56:12,860

1153
00:56:12,860 --> 00:56:15,460
Na hii ni kwa nini ni kidogo
tedious na si kutumia jQuery.

1154
00:56:15,460 --> 00:56:16,710
"Jina" thamani..

1155
00:56:16,710 --> 00:56:18,330

1156
00:56:18,330 --> 00:56:19,620
Hivyo kabisa kukubalika.

1157
00:56:19,620 --> 00:56:22,770
Njia tofauti za kufanya hivyo. jQuery tu
huelekea kuwa succinct kidogo zaidi na

1158
00:56:22,770 --> 00:56:25,230
dhahiri maarufu zaidi
kati ya programmers.

1159
00:56:25,230 --> 00:56:27,590
>> Sasa, mimi nina kufanya kidogo ya sanity
kuangalia, kwa sababu katika tatizo

1160
00:56:27,590 --> 00:56:30,820
taarifa sisi waziwazi alisema, kama
user bado typed yake

1161
00:56:30,820 --> 00:56:32,580
jina, hawaonyeshi alerts.

1162
00:56:32,580 --> 00:56:35,390
Lakini unaweza kuangalia kwa kuwa, kwa kuwa tu
kuangalia kwa kamba tupu kwa

1163
00:56:35,390 --> 00:56:37,850
quote-unquote kama kuna
kitu kweli huko.

1164
00:56:37,850 --> 00:56:40,880
Lakini kama ni si sawa kunukuu-unquote,
Nataka kuwaita alerts.

1165
00:56:40,880 --> 00:56:45,610
Na sehemu ya kuvutia hapa ni kwamba
sisi ni kutumia pamoja na operator, ambayo

1166
00:56:45,610 --> 00:56:48,130
anafanya nini katika JavaScript?

1167
00:56:48,130 --> 00:56:48,740
Concatenate.

1168
00:56:48,740 --> 00:56:50,690
Hivyo ni kama PHPs dot operator.

1169
00:56:50,690 --> 00:56:52,820
Same wazo, syntax tofauti kidogo.

1170
00:56:52,820 --> 00:56:55,280
Na mimi nina kujenga kamba tu kwamba
wewe aliona juu ya screen risasi -

1171
00:56:55,280 --> 00:56:57,750
Hello, hivyo na hivyo.

1172
00:56:57,750 --> 00:56:59,200
>> Na kisha undani mwisho ni hii.

1173
00:56:59,200 --> 00:57:04,970
Kwa nini mimi kurudi ndani ya uongo
wa kazi hii bila majina?

1174
00:57:04,970 --> 00:57:07,420
>> Watazamaji: Hakuna thamani.

1175
00:57:07,420 --> 00:57:09,380
Kuiweka katika fomu.

1176
00:57:09,380 --> 00:57:12,320

1177
00:57:12,320 --> 00:57:16,730
Ni tu anasema, ikiwa thamani ni si
sawa tupu, basi kufanya hivyo.

1178
00:57:16,730 --> 00:57:20,040

1179
00:57:20,040 --> 00:57:20,940
Kulikuwa na tupu katika kuwasilisha.

1180
00:57:20,940 --> 00:57:21,170
>> DAVID J. Malan: OK.

1181
00:57:21,170 --> 00:57:21,640
Makini ingawa.

1182
00:57:21,640 --> 00:57:22,830
Hakuna mtu mwingine hapa.

1183
00:57:22,830 --> 00:57:25,510
Na kwamba kurudi uongo ni nje
la kama masharti.

1184
00:57:25,510 --> 00:57:29,470
Hivyo hii yalionyesha line, kurudi uongo,
executes bila kujali wakati

1185
00:57:29,470 --> 00:57:32,310
fomu ni kuwasilishwa.

1186
00:57:32,310 --> 00:57:36,810
Gani kurejea ndani ya uongo ya hii
tukio handler, kama ni kuitwa,

1187
00:57:36,810 --> 00:57:38,450
tukio katika swali
kuwa kuwasilisha?

1188
00:57:38,450 --> 00:57:42,350

1189
00:57:42,350 --> 00:57:44,470
>> Watazamaji: Kwa sababu
hutokea tu mara moja.

1190
00:57:44,470 --> 00:57:45,320
>> DAVID J. Malan: Ni hufanyika mara moja.

1191
00:57:45,320 --> 00:57:46,821
Kabisa.

1192
00:57:46,821 --> 00:57:47,292
Yeah?

1193
00:57:47,292 --> 00:57:50,589
>> Watazamaji: Ni kuzuia fomu kutoka kwa
kuwasilisha na tabia default,

1194
00:57:50,589 --> 00:57:52,480
ambayo kufanya ukurasa Reload.

1195
00:57:52,480 --> 00:57:53,110
>> DAVID J. Malan: Hasa.

1196
00:57:53,110 --> 00:57:56,490
Hivyo mimi nina overloading mrefu kuwasilisha hapa,
kwa sababu mimi kusema, fomu ni

1197
00:57:56,490 --> 00:57:57,670
kuwa kuwasilishwa.

1198
00:57:57,670 --> 00:58:02,240
Lakini kama wewe kupendekeza, ni kweli si
kuwasilishwa katika kweli HTTP njia.

1199
00:58:02,240 --> 00:58:06,870
Wakati bonyeza Kuwasilisha, kwa sababu ya yetu
onSubmit handler, sisi ni kukamata

1200
00:58:06,870 --> 00:58:09,040
kwamba kuwasilisha fomu hivyo kusema.

1201
00:58:09,040 --> 00:58:11,290
Sisi ni kisha kufanya mambo yetu
na JavaScript code.

1202
00:58:11,290 --> 00:58:14,070
Lakini mimi nina kwa makusudi kurudi uongo,
kwa sababu gani Sitaki kutokea

1203
00:58:14,070 --> 00:58:18,430
mgawanyiko wa pili baadaye ni kwa umbo lake lote
yenyewe kuwasilishwa kwa mtandao

1204
00:58:18,430 --> 00:58:22,800
server kwa thamani jozi muhimu kwa kubadilisha
URL kuwa kitu kama

1205
00:58:22,800 --> 00:58:26,180
q = paka au chochote sisi hivyo,
kwa mfano, katika darasa.

1206
00:58:26,180 --> 00:58:29,640
Sitaki hilo kutokea, kwa sababu
hakuna kusikiliza server kwa hii

1207
00:58:29,640 --> 00:58:30,690
kuwasilisha fomu.

1208
00:58:30,690 --> 00:58:32,320
Ni rena kufanyika katika JavaScript code.

1209
00:58:32,320 --> 00:58:35,760
Na kwamba ni kwa nini mimi hakuwa na hata kuwa
hatua sifa katika fomu yangu, kwa sababu mimi

1210
00:58:35,760 --> 00:58:38,870
sitaki kwa hili
milele kwenda kwa server.

1211
00:58:38,870 --> 00:58:40,780
>> Hivyo ni kuwa in.

1212
00:58:40,780 --> 00:58:44,340
Lakini sisi ni kukamata fomu kuwa
kuwasilisha na kuzuia default

1213
00:58:44,340 --> 00:58:47,477
tabia, ambayo ni kweli
kwenda njia yote ya server.

1214
00:58:47,477 --> 00:58:48,730
>> Watazamaji: Kwa hiyo kuweka mteja upande.

1215
00:58:48,730 --> 00:58:49,780
>> DAVID J. Malan: Kuweka
ni mteja upande.

1216
00:58:49,780 --> 00:58:51,030
Hasa haki.

1217
00:58:51,030 --> 00:58:53,240

1218
00:58:53,240 --> 00:58:55,757
Next up mara yangu ya oh MySQL.

1219
00:58:55,757 --> 00:59:00,000

1220
00:59:00,000 --> 00:59:00,430
>> Rob BOWDEN: OK.

1221
00:59:00,430 --> 00:59:04,990
Hivyo swali hili kwanza kwa ujumla
mbaya kwa watu.

1222
00:59:04,990 --> 00:59:07,270
Ingawa ndio baadaye alikwenda bora.

1223
00:59:07,270 --> 00:59:12,260
Hivyo alikuwa na kuchagua data sahihi
aina kwa ajili ya wote nguzo hizi.

1224
00:59:12,260 --> 00:59:17,750
Na wote hawa na baadhi
mambo yao kwamba

1225
00:59:17,750 --> 00:59:20,620
kufanya uchaguzi mgumu.

1226
00:59:20,620 --> 00:59:24,430
Hivyo int hakuwa halali
aina kwa idadi.

1227
00:59:24,430 --> 00:59:29,410
Sababu ya kuwa akaunti 12-tarakimu
posta, int si kubwa ya kutosha kwa

1228
00:59:29,410 --> 00:59:31,070
kuhifadhi tarakimu jumla.

1229
00:59:31,070 --> 00:59:36,570
Hivyo uchaguzi halali ingekuwa kubwa
int kama kutokea kwa kujua kwamba.

1230
00:59:36,570 --> 00:59:42,090
Uchaguzi mwingine wangeweza
char uwanja wa urefu 12.

1231
00:59:42,090 --> 00:59:44,560
Hivyo ama ya wale ingekuwa kazi.

1232
00:59:44,560 --> 00:59:46,100
Int bila.

1233
00:59:46,100 --> 00:59:50,170
>> Sasa, mizani, kufikiri nyuma pset7.

1234
00:59:50,170 --> 00:59:59,540
Hivyo sisi hasa kutumika decimal kwa
kuhifadhi thamani ya hisa au -

1235
00:59:59,540 --> 01:00:00,550
>> DAVID J. Malan: Fedha.

1236
01:00:00,550 --> 01:00:01,060
>> Rob BOWDEN: Fedha.

1237
01:00:01,060 --> 01:00:05,710
Tulikuwa decimal kuhifadhi kiasi cha
fedha kwamba mtumiaji sasa ina.

1238
01:00:05,710 --> 01:00:10,950
Hivyo sababu sisi kufanya hivyo ni
kwa sababu, kumbuka, ikifungwa.

1239
01:00:10,950 --> 01:00:12,480
Kuna yaliyo hatua katika usahihi ni.

1240
01:00:12,480 --> 01:00:18,200
Haiwezi just kuhifadhi fedha
maadili kama tunataka hapa.

1241
01:00:18,200 --> 01:00:23,630
Hivyo decimal ni uwezo wa usahihi duka
kitu, kusema, maeneo mawili decimal.

1242
01:00:23,630 --> 01:00:27,630
Hiyo ni kwa nini usawa, tunataka
kuwa decimal na si kuelea.

1243
01:00:27,630 --> 01:00:30,230
>> DAVID J. Malan: Na pia, pia, ingawa
Yangaliweza wajanja katika nchi nyingine

1244
01:00:30,230 --> 01:00:32,760
mazingira kufikiri, labda hii
ni nafasi kwa int.

1245
01:00:32,760 --> 01:00:34,420
Mimi itabidi kuweka wimbo wa
mambo katika pennies.

1246
01:00:34,420 --> 01:00:38,670
Kwa sababu sisi wazi ilionyesha default
thamani ya kuwa 100.00, kwamba

1247
01:00:38,670 --> 01:00:40,380
maana inaweza tu kuwa int.

1248
01:00:40,380 --> 01:00:45,310
Na hila nyingine pia na idadi
ni kwamba hakuwa na maana

1249
01:00:45,310 --> 01:00:46,180
kuwa swali hila.

1250
01:00:46,180 --> 01:00:49,860
Lakini kukumbuka kuwa int katika MySQL,
kama katika C, angalau katika

1251
01:00:49,860 --> 01:00:51,440
appliance, ni 32-bit.

1252
01:00:51,440 --> 01:00:53,960
Na hata kama hatuna wanatarajia
kujua hasa jinsi tarakimu nyingi kwamba

1253
01:00:53,960 --> 01:00:56,910
maana yake, wala kukumbuka kwamba idadi kubwa
unaweza kuwakilisha uwezekano wa

1254
01:00:56,910 --> 01:01:00,710
na 32-bit idadi ni takribani nini?

1255
01:01:00,710 --> 01:01:02,760
>> Nini idadi wala sisi daima kusema?

1256
01:01:02,760 --> 01:01:04,530
2-32, ambayo ni nini takribani?

1257
01:01:04,530 --> 01:01:07,492

1258
01:01:07,492 --> 01:01:08,780
Huwezi kujua kwa usahihi.

1259
01:01:08,780 --> 01:01:10,580
Lakini takribani ni muhimu katika maisha.

1260
01:01:10,580 --> 01:01:12,200
Ni takribani bilioni 4.

1261
01:01:12,200 --> 01:01:14,430
Hivyo tumekuwa alisema kuwa mara chache.

1262
01:01:14,430 --> 01:01:16,360
Mimi najua kuwa alisema kuwa mara chache.

1263
01:01:16,360 --> 01:01:17,670
Na ni takribani bilioni 4.

1264
01:01:17,670 --> 01:01:19,710
Na kwamba utawala bora
ya thumb kujua.

1265
01:01:19,710 --> 01:01:21,880
Kama una 8 bits, 256
Idadi ya uchawi.

1266
01:01:21,880 --> 01:01:24,160
Kama una bits 32, 4
bilioni kutoa au kuchukua.

1267
01:01:24,160 --> 01:01:27,140
Hivyo kama wewe tu kuandika bilioni 4,
utaona kwamba ni tarakimu chache kuliko

1268
01:01:27,140 --> 01:01:30,970
12, ambayo ina maana kwamba ni wazi si
expressiveness kutosha kukamata

1269
01:01:30,970 --> 01:01:34,220
12-tarakimu idadi ya akaunti.

1270
01:01:34,220 --> 01:01:34,940
>> Rob BOWDEN: OK.

1271
01:01:34,940 --> 01:01:38,520
Hivyo wale wengine akaenda bora.

1272
01:01:38,520 --> 01:01:40,900
Hivyo tuseme kwamba benki
inaweka $ 20 kila mwezi

1273
01:01:40,900 --> 01:01:42,400
ada matengenezo ya akaunti zote.

1274
01:01:42,400 --> 01:01:45,506
Kwa nini SQL swala inaweza benki
dra $ 20 kutoka kila kuhesabu, hata kama

1275
01:01:45,506 --> 01:01:47,520
matokeo yake ni baadhi mizani mbaya?

1276
01:01:47,520 --> 01:01:50,380
Hivyo kimsingi, kuna nne
kuu ya aina ya maswali -

1277
01:01:50,380 --> 01:01:52,840
kuingiza, kuchagua, update, na kufuta.

1278
01:01:52,840 --> 01:01:56,080
Basi je, tunafikiri ni
kwenda kutumia hapa?

1279
01:01:56,080 --> 01:01:57,000
Mwisho.

1280
01:01:57,000 --> 01:01:58,260
>> Hivyo basi tuangalie.

1281
01:01:58,260 --> 01:02:04,290

1282
01:02:04,290 --> 01:02:05,870
Hivyo hapa sisi ni kuhuisha.

1283
01:02:05,870 --> 01:02:09,900
Nini meza ni sisi kuhuisha akaunti?

1284
01:02:09,900 --> 01:02:11,670
Hivyo kuhuisha akaunti.

1285
01:02:11,670 --> 01:02:15,390
Na kisha syntax anasema, nini
katika akaunti ni sisi kuongezea?

1286
01:02:15,390 --> 01:02:19,520
Naam, sisi ni kuweka uwiano sawa na
thamani ya sasa ya usawa minus 20.

1287
01:02:19,520 --> 01:02:22,860
Hivyo hii itakuwa update safu zote
ya akaunti, kutoa mapato

1288
01:02:22,860 --> 01:02:26,250
$ 20 kutoka usawa.

1289
01:02:26,250 --> 01:02:29,260
>> DAVID J. Malan: makosa ya kawaida hapa,
ingawa sisi wakati mwingine cha kusamehe,

1290
01:02:29,260 --> 01:02:32,990
ilikuwa kweli kuwa PHP code hapa
wito kazi swala au kuweka

1291
01:02:32,990 --> 01:02:35,460
quotes karibu kila kitu
hakuwa na haja ya kuwa huko.

1292
01:02:35,460 --> 01:02:39,780
>> Rob BOWDEN: Kumbuka ya kwamba MySQL ni
lugha tofauti na PHP.

1293
01:02:39,780 --> 01:02:42,410
Sisi kutokea kwa kuwa kuandika MySQL katika PHP.

1294
01:02:42,410 --> 01:02:46,180
Na PHP ni kisha kupeleka
juu ya MySQL server.

1295
01:02:46,180 --> 01:02:51,120
Lakini huna haja ya PHP ili
kuwasiliana na MySQL server.

1296
01:02:51,120 --> 01:02:51,730
>> DAVID J. Malan: Hasa.

1297
01:02:51,730 --> 01:02:54,240
Hivyo hakuna vigezo na dola ishara
lazima katika suala hili.

1298
01:02:54,240 --> 01:02:59,550
Ni anaweza kufanya yote ya math
ndani ya database yenyewe.

1299
01:02:59,550 --> 01:03:00,080
>> Rob BOWDEN: OK.

1300
01:03:00,080 --> 01:03:01,300
Hivyo moja ijayo.

1301
01:03:01,300 --> 01:03:02,731
Je, hii ni moja ijayo?

1302
01:03:02,731 --> 01:03:03,210
Yeah.

1303
01:03:03,210 --> 01:03:06,570
Hivyo, pamoja na kile SQL swala inaweza benki
retrieve idadi ya akaunti ya yake

1304
01:03:06,570 --> 01:03:09,300
wateja tajiri, wale walio na
mizani zaidi ya 1,000?

1305
01:03:09,300 --> 01:03:13,280
Hivyo ambayo ya aina kuu nne
sisi ni kwenda kutaka hapa?

1306
01:03:13,280 --> 01:03:14,430
Kuchagua.

1307
01:03:14,430 --> 01:03:16,650
Hivyo tunataka kuchagua.

1308
01:03:16,650 --> 01:03:17,610
Je, tunataka kuchagua?

1309
01:03:17,610 --> 01:03:19,380
Nini safu tunataka kuchagua?

1310
01:03:19,380 --> 01:03:20,970
Sisi hasa wanataka
kuchagua idadi.

1311
01:03:20,970 --> 01:03:23,910
Lakini kama wewe alisema nyota, sisi
pia kukubaliwa kuwa.

1312
01:03:23,910 --> 01:03:25,820
>> Hivyo kuchagua idadi kutoka meza nini?

1313
01:03:25,820 --> 01:03:26,640
Akaunti.

1314
01:03:26,640 --> 01:03:28,370
Na kisha hali tunataka?

1315
01:03:28,370 --> 01:03:30,140
Ambapo uwiano zaidi ya 1,000.

1316
01:03:30,140 --> 01:03:31,720
Sisi pia kukubalika zaidi
zaidi kuliko au sawa.

1317
01:03:31,720 --> 01:03:35,230

1318
01:03:35,230 --> 01:03:36,190
Moja ya mwisho.

1319
01:03:36,190 --> 01:03:42,940
Kwa nini SQL swala inaweza benki
karibu, yaani, kufuta kila akaunti ya kwamba

1320
01:03:42,940 --> 01:03:44,480
ina uwiano wa $ 0?

1321
01:03:44,480 --> 01:03:47,620
Hivyo ambayo ya nne ni sisi
kwenda unataka kutumia?

1322
01:03:47,620 --> 01:03:48,320
Kufuta.

1323
01:03:48,320 --> 01:03:50,180
Hivyo syntax kwa kuwa?

1324
01:03:50,180 --> 01:03:51,890
Kufuta kutoka meza nini?

1325
01:03:51,890 --> 01:03:53,550
Akaunti.

1326
01:03:53,550 --> 01:03:55,790
Na kisha hali ambayo
sisi unataka kufuta -

1327
01:03:55,790 --> 01:03:57,280
ambapo uwiano sawa na sifuri.

1328
01:03:57,280 --> 01:04:03,050
Hivyo kufuta safu zote kutoka akaunti ya
ambapo uwiano ni zero.

1329
01:04:03,050 --> 01:04:04,300
Maswali yoyote ya haya?

1330
01:04:04,300 --> 01:04:08,840

1331
01:04:08,840 --> 01:04:10,260
Wanataka foleni?

1332
01:04:10,260 --> 01:04:11,200
>> DAVID J. Malan: Foleni mwongozo.

1333
01:04:11,200 --> 01:04:17,110
Hivyo katika hii moja, tuliwapa kiasi fulani
muundo familiar kwamba sisi kutalii a

1334
01:04:17,110 --> 01:04:20,450
kidogo katika darasa pamoja ya structs,
ambayo ilikuwa data

1335
01:04:20,450 --> 01:04:21,910
muundo kuhusiana katika roho.

1336
01:04:21,910 --> 01:04:24,670
tofauti ingawa kwa foleni ni
kwamba alikuwa kwa namna fulani kukumbuka ambao

1337
01:04:24,670 --> 01:04:27,900
ilikuwa mbele ya foleni, katika kubwa
sehemu ili tuweze kufanya zaidi

1338
01:04:27,900 --> 01:04:30,530
matumizi bora ya kumbukumbu, angalau
kama tungetumia safu.

1339
01:04:30,530 --> 01:04:35,460
>> Kwa sababu wanakumbuka, kama tuna safu, ikiwa
kwa mfano, hii ni mbele ya

1340
01:04:35,460 --> 01:04:38,470
foleni, kama mimi kupata katika foleni hapa,
na kisha mtu anapata katika line

1341
01:04:38,470 --> 01:04:42,710
nyuma yangu, nyuma yangu, nyuma yangu, na
mtu mmoja hatua nje ya mstari,

1342
01:04:42,710 --> 01:04:45,930
anaweza, kama sisi kuona baadhi ya binadamu yetu
kujitolea katika darasa, na kila mtu

1343
01:04:45,930 --> 01:04:47,100
kuhama kwa njia hii.

1344
01:04:47,100 --> 01:04:50,880
Lakini kwa ujumla, baada ya kila mtu kufanya
kitu si matumizi bora ya wakati

1345
01:04:50,880 --> 01:04:54,600
katika mpango, kwa sababu ina maana yako
algorithm ni mbio katika kile

1346
01:04:54,600 --> 01:04:56,520
asymptotic mbio wakati?

1347
01:04:56,520 --> 01:04:57,420
Ni linear.

1348
01:04:57,420 --> 01:04:59,600
>> Na mimi kuhisi kama kwamba aina ya kijinga.

1349
01:04:59,600 --> 01:05:02,890
Kama mtu mwingine katika line ni karibu
mtu ambaye wanatakiwa kwenda katika

1350
01:05:02,890 --> 01:05:04,660
kuhifadhi, hawana wote wana
hoja pamoja.

1351
01:05:04,660 --> 01:05:08,200
Tu basi mtu huyo kuwa kuwang'oa
wakati unakuja, kwa mfano.

1352
01:05:08,200 --> 01:05:09,870
Ili tuweze kuokoa muda kidogo huko.

1353
01:05:09,870 --> 01:05:14,840
Na kufanya hivyo kwamba kuwa, njia
kuwa kichwa cha foleni au

1354
01:05:14,840 --> 01:05:18,060
mbele ya foleni ni kwenda
kuendelea hoja zaidi na zaidi

1355
01:05:18,060 --> 01:05:23,340
katika safu na hatimaye nguvu
kweli wrap kuzunguka kama sisi ni kutumia

1356
01:05:23,340 --> 01:05:25,790
safu ya kuhifadhi watu
katika foleni hii.

1357
01:05:25,790 --> 01:05:28,390
Hivyo unaweza karibu kufikiri ya
safu kama data mviringo

1358
01:05:28,390 --> 01:05:29,880
muundo kwa maana ya kwamba.

1359
01:05:29,880 --> 01:05:33,970
>> Hivyo kwa namna fulani na kuweka wimbo wa
ukubwa wa au kweli mwisho wa ni

1360
01:05:33,970 --> 01:05:36,250
na kisha ambapo mwanzo wa ni.

1361
01:05:36,250 --> 01:05:39,490
Hivyo sisi kupendekeza kwamba kutangaza
moja foleni hiyo, wito

1362
01:05:39,490 --> 01:05:41,330
ni q, barua moja tu.

1363
01:05:41,330 --> 01:05:44,570
Kisha sisi kupendekeza kwamba mbele kuwa na
kuanzishwa kwa zero na kwamba ukubwa

1364
01:05:44,570 --> 01:05:45,470
kuanzishwa kwa sifuri.

1365
01:05:45,470 --> 01:05:47,770
>> Hivyo sasa hivi, kuna kitu
ndani ya foleni hiyo.

1366
01:05:47,770 --> 01:05:50,910
Na tunakuomba kukamilisha
utekelezaji wa enqueue chini katika

1367
01:05:50,910 --> 01:05:55,250
namna ambayo kazi anaongeza n kwa
mwisho wa q na kisha anarudi kweli.

1368
01:05:55,250 --> 01:05:58,690
Lakini kama q ni full au hasi,
kazi badala yake kurudi uongo.

1369
01:05:58,690 --> 01:06:01,060
Na tuliwapa wanandoa
ya mawazo.

1370
01:06:01,060 --> 01:06:04,320
Lakini wao siyo kweli functionally
husika, tu kwamba bool ipo,

1371
01:06:04,320 --> 01:06:06,690
kwa sababu, kitaalam, bool haina
zipo katika C kama wewe ni pamoja na

1372
01:06:06,690 --> 01:06:07,310
baadhi ya header file.

1373
01:06:07,310 --> 01:06:09,350
Ili mara tu kuhakikisha kuna
walikuwa hakuna ni hii hila

1374
01:06:09,350 --> 01:06:10,940
swali aina ya kitu.

1375
01:06:10,940 --> 01:06:16,280
>> Hivyo enqueue, sisi mapendekezo katika sampuli
ufumbuzi wa kutekeleza kama ifuatavyo.

1376
01:06:16,280 --> 01:06:20,420
Moja, sisi kwanza kuangalia urahisi,
chini ya kunyongwa matunda.

1377
01:06:20,420 --> 01:06:23,820
Kama foleni ni kamili au idadi hiyo
wewe ni kujaribu kuingiza ni chini ya

1378
01:06:23,820 --> 01:06:26,380
kuliko sifuri, ambayo sisi alisema katika
vipimo ya tatizo lazima

1379
01:06:26,380 --> 01:06:30,320
si kuruhusiwa, kwa sababu sisi tu wanataka
maadili mashirika yasiyo ya hasi, basi lazima

1380
01:06:30,320 --> 01:06:31,640
tu kurudi uongo mara moja.

1381
01:06:31,640 --> 01:06:33,820
Kwa hiyo baadhi ya rahisi
makosa kuangalia.

1382
01:06:33,820 --> 01:06:38,720
Kama ingawa unataka kuongeza kuwa halisi
posta, alikuwa na kufanya kidogo ya

1383
01:06:38,720 --> 01:06:39,440
kufikiri hapa.

1384
01:06:39,440 --> 01:06:41,330
Na hii ni mahali ambapo ni kidogo annoying
kiakili, kwa sababu una

1385
01:06:41,330 --> 01:06:43,000
kufikiri jinsi ya kushughulikia wraparound.

1386
01:06:43,000 --> 01:06:46,870
>> Lakini kadhalika ya wazo hapa kwamba ya
maslahi kwetu ni kwamba wraparound

1387
01:06:46,870 --> 01:06:51,480
mara nyingi ina maana msimu hesabu na
operator mod, upande asilimia,

1388
01:06:51,480 --> 01:06:55,140
ambapo unaweza kwenda kutoka thamani kubwa
nyuma hadi kufikia sifuri na kisha moja na mbili na

1389
01:06:55,140 --> 01:06:58,650
tatu na kisha nyuma karibu na sifuri,
moja na mbili na tatu na kadhalika

1390
01:06:58,650 --> 01:06:59,380
tena na tena.

1391
01:06:59,380 --> 01:07:02,880
Hivyo njia sisi kupendekeza kufanya hivyo ni
kwamba hatutaki index katika

1392
01:07:02,880 --> 01:07:05,850
safu kuitwa idadi ambapo
integers yetu uongo.

1393
01:07:05,850 --> 01:07:10,740
Lakini kufika huko, sisi kwanza wanataka kufanya
kila kawaida ya foleni ni lakini

1394
01:07:10,740 --> 01:07:14,080
kisha kuongeza kwamba kila
mbele ya orodha ni.

1395
01:07:14,080 --> 01:07:17,880
Na athari za kuwa ni kuweka yetu katika
nafasi ya haki katika foleni na

1396
01:07:17,880 --> 01:07:20,970
si kudhani kuwa mtu wa kwanza katika line
ni mwanzo, ambayo yeye au

1397
01:07:20,970 --> 01:07:24,130
yeye kabisa inaweza kuwa kama sisi
walikuwa pia kuhama kila mtu.

1398
01:07:24,130 --> 01:07:26,710
Lakini sisi ni kujenga tu kazi
kwa wenyewe kama sisi alichukua

1399
01:07:26,710 --> 01:07:27,800
kwamba njia fulani.

1400
01:07:27,800 --> 01:07:29,330
>> Ili tuweze kuitunza rahisi.

1401
01:07:29,330 --> 01:07:32,180
Sisi kukumbuka kwamba sisi tu
Aliongeza int kwa foleni.

1402
01:07:32,180 --> 01:07:35,850
Na kisha sisi tu kurudi kweli.

1403
01:07:35,850 --> 01:07:38,560
Wakati huo huo, katika dequeue, sisi aliuliza
wewe kufanya yafuatayo.

1404
01:07:38,560 --> 01:07:42,260
Kutekeleza katika namna ambayo
dequeues, kwamba ni kuondosha na kurudi,

1405
01:07:42,260 --> 01:07:44,190
int mbele ya foleni.

1406
01:07:44,190 --> 01:07:46,410
Kuondoa int, yatosha
kusahau.

1407
01:07:46,410 --> 01:07:47,650
Huna haja ya kupuuza kidogo wake.

1408
01:07:47,650 --> 01:07:48,820
Hivyo ni kweli kuna bado.

1409
01:07:48,820 --> 01:07:51,930
Tu kama data kwenye gari ngumu,
sisi ni kupuuza tu ukweli

1410
01:07:51,930 --> 01:07:52,970
kwamba ni huko sasa.

1411
01:07:52,970 --> 01:07:55,520
Na kama q ni tupu, sisi lazima
badala kurudi hasi 1.

1412
01:07:55,520 --> 01:07:56,750
Hivyo hii anahisi holela.

1413
01:07:56,750 --> 01:08:01,640
Kwa nini kurudi hasi 1
badala ya uongo?

1414
01:08:01,640 --> 01:08:02,620
Yeah.

1415
01:08:02,620 --> 01:08:05,070
>> Watazamaji: Q ni hifadhi ya
maadili mazuri.

1416
01:08:05,070 --> 01:08:10,950
Tangu wewe tu kuhifadhi maadili mazuri
katika q, hasi ni kosa.

1417
01:08:10,950 --> 01:08:11,510
>> DAVID J. Malan: OK, kweli.

1418
01:08:11,510 --> 01:08:14,850
Basi, kwa sababu sisi ni tu kuhifadhi chanya
maadili au sifuri, basi ni faini ya

1419
01:08:14,850 --> 01:08:18,050
kurudi thamani hasi kama mwangalizi
thamani, alama maalum.

1420
01:08:18,050 --> 01:08:21,630
Lakini wewe ni marudio ya andiko historia huko,
kwa sababu sababu tuko tu

1421
01:08:21,630 --> 01:08:25,890
kurudi maadili mashirika yasiyo ya hasi
ni kwa sababu tunataka

1422
01:08:25,890 --> 01:08:27,670
na thamani mwangalizi.

1423
01:08:27,670 --> 01:08:32,617
Hivyo zaidi hasa, kwa nini siyo tu
kurudi uongo katika kesi ya makosa?

1424
01:08:32,617 --> 01:08:33,099
Yeah.

1425
01:08:33,099 --> 01:08:35,510
>> Watazamaji: You wameweza kushindwa
kurudi integer.

1426
01:08:35,510 --> 01:08:36,630
>> DAVID J. Malan: Hasa.

1427
01:08:36,630 --> 01:08:38,569
Na hii ni ambapo C anapata
pretty constraining.

1428
01:08:38,569 --> 01:08:40,590
Kama wewe ni kusema wewe ni kwenda
kurudi int, nimepata

1429
01:08:40,590 --> 01:08:41,279
kurudi int.

1430
01:08:41,279 --> 01:08:43,689
Huwezi kupata dhana na kuanza kurudi
bool au kuelea au

1431
01:08:43,689 --> 01:08:45,040
kamba au kitu kama hicho.

1432
01:08:45,040 --> 01:08:49,370
Sasa, wakati huo huo, JavaScript na PHP na
lugha nyingine unaweza, kwa kweli,

1433
01:08:49,370 --> 01:08:51,310
wewe kurudi mbalimbali
aina ya maadili.

1434
01:08:51,310 --> 01:08:54,819
Na kwamba kweli anaweza kuwa na manufaa, ambapo
unaweza kurudi ints chanya, zeros,

1435
01:08:54,819 --> 01:08:59,439
ints hasi, au uongo au null
hata kwa ishara ya makosa.

1436
01:08:59,439 --> 01:09:01,890
Lakini hatuna kwamba
versatility katika C.

1437
01:09:01,890 --> 01:09:04,569
>> Hivyo, pamoja na dequeue, je, sisi
kupendekeza kufanya ni -

1438
01:09:04,569 --> 01:09:07,350

1439
01:09:07,350 --> 01:09:09,830
>> Rob BOWDEN: Unaweza kurudi uongo.

1440
01:09:09,830 --> 01:09:13,189
Ni tu kwamba uongo ni hash
kufafanua uongo na sifuri.

1441
01:09:13,189 --> 01:09:16,000
Hivyo kama wewe kurudi uongo,
wewe ni kurudi sifuri.

1442
01:09:16,000 --> 01:09:25,470
Na zero ni kitu halali katika foleni zetu,
ambapo hasi 1 si kama

1443
01:09:25,470 --> 01:09:27,000
uongo kilichotokea kuwa hasi 1.

1444
01:09:27,000 --> 01:09:29,972
Lakini lazima hata
haja ya kujua kwamba.

1445
01:09:29,972 --> 01:09:32,399
>> DAVID J. Malan: Hiyo ni
kwa nini mimi si kusema hivyo.

1446
01:09:32,399 --> 01:09:36,450
>> Rob BOWDEN: Lakini haikuwa kweli
kwamba huwezi kurudi uongo.

1447
01:09:36,450 --> 01:09:37,700
>> DAVID J. Malan: Uhakika.

1448
01:09:37,700 --> 01:09:40,920

1449
01:09:40,920 --> 01:09:44,240
Hivyo dequeue, taarifa sisi kukubali
utupu kama hoja yake.

1450
01:09:44,240 --> 01:09:45,479
Na kwamba kwa sababu sisi siyo
kupita kitu chochote in

1451
01:09:45,479 --> 01:09:48,359
Sisi tu unataka kuondoa hiki
mbele ya foleni.

1452
01:09:48,359 --> 01:09:49,819
Hivyo jinsi gani sisi kwenda juu ya kufanya hii?

1453
01:09:49,819 --> 01:09:51,290
Naam, kwanza, hebu kufanya hivyo
haraka sanity kuangalia.

1454
01:09:51,290 --> 01:09:53,350
Kama foleni ukubwa ni 0, kuna
hakuna kazi kufanyika.

1455
01:09:53,350 --> 01:09:54,210
Kurudi hasi 1.

1456
01:09:54,210 --> 01:09:54,800
Kufanyika.

1457
01:09:54,800 --> 01:09:56,340
Hivyo kwamba ni mistari michache ya mpango wangu.

1458
01:09:56,340 --> 01:09:58,180
Hivyo mistari minne tu kubaki.

1459
01:09:58,180 --> 01:10:01,310
>> Hivyo hapa mimi kuamua kuongezwa
kawaida.

1460
01:10:01,310 --> 01:10:04,620
Na decrementing ukubwa ufanisi
ina maana kwamba mimi nina kusahau

1461
01:10:04,620 --> 01:10:06,010
kitu ni huko.

1462
01:10:06,010 --> 01:10:09,910
Lakini mimi pia kuwa na update ambapo
mbele ya idadi ni.

1463
01:10:09,910 --> 01:10:11,620
Hivyo kufanya hivyo, mimi haja
kufanya mambo mawili.

1464
01:10:11,620 --> 01:10:16,390
Mimi kwanza haja ya kukumbuka nini idadi
ni mbele ya foleni,

1465
01:10:16,390 --> 01:10:17,860
kwa sababu mimi haja ya kurudi kitu hicho.

1466
01:10:17,860 --> 01:10:20,910
Basi, mimi sitaki ajali kusahau
kuhusu hilo na kisha overwrite.

1467
01:10:20,910 --> 01:10:22,840
Mimi tu kwenda kukumbuka katika int.

1468
01:10:22,840 --> 01:10:27,310
>> Na sasa, nataka update
q.front kuwa q.front 1.

1469
01:10:27,310 --> 01:10:30,070
Hivyo kama hii alikuwa mtu wa kwanza katika
line, sasa, nataka kufanya plus 1 kwa

1470
01:10:30,070 --> 01:10:31,930
uhakika katika mtu mwingine katika line.

1471
01:10:31,930 --> 01:10:33,420
Lakini nina kushughulikia kwamba wraparound.

1472
01:10:33,420 --> 01:10:37,270
Na kama uwezo ni mara kwa mara kimataifa,
ambayo inaenda naomba kuhakikisha

1473
01:10:37,270 --> 01:10:41,140
kama mimi uhakika na mtu wa mwisho sana katika
line, operesheni modulo kuleta

1474
01:10:41,140 --> 01:10:43,840
mimi nyuma kwa sifuri katika
mbele ya foleni.

1475
01:10:43,840 --> 01:10:46,050
Na kwamba Hushughulikia wraparound hapa.

1476
01:10:46,050 --> 01:10:48,950
Na kisha mimi kuendelea na kurudi n.

1477
01:10:48,950 --> 01:10:51,530
>> Sasa, madhubuti kusema, mimi si
na kutangaza n.

1478
01:10:51,530 --> 01:10:53,880
Mimi hakuwa na kunyakua hiyo na kuhifadhi
muda, kwa sababu thamani ni

1479
01:10:53,880 --> 01:10:54,740
bado yapo.

1480
01:10:54,740 --> 01:10:57,490
Ili niweze tu kufanya hesabu sahihi
kurudi mkuu wa zamani

1481
01:10:57,490 --> 01:10:58,450
ya foleni.

1482
01:10:58,450 --> 01:11:01,850
Lakini mimi tu waliona kuwa hii ilikuwa wazi zaidi
kwa kweli kunyakua int, kuiweka

1483
01:11:01,850 --> 01:11:04,320
katika n, na kisha kurudi kwamba
kwa ajili uwazi lakini

1484
01:11:04,320 --> 01:11:05,735
si madhubuti muhimu.

1485
01:11:05,735 --> 01:11:09,313

1486
01:11:09,313 --> 01:11:12,130
Psst.

1487
01:11:12,130 --> 01:11:13,410
Wao ni wote semekana katika kichwa changu.

1488
01:11:13,410 --> 01:11:15,940

1489
01:11:15,940 --> 01:11:19,110
>> Rob BOWDEN: Kwa hiyo swali la kwanza
ni mti binary tatizo.

1490
01:11:19,110 --> 01:11:22,140
Hivyo swali la kwanza ni, sisi ni
kutokana na idadi haya.

1491
01:11:22,140 --> 01:11:27,160
Na tunataka kwa namna fulani Insert yao katika
nodes haya kama kwamba ni

1492
01:11:27,160 --> 01:11:30,110
halali binary search mti.

1493
01:11:30,110 --> 01:11:36,260
Hivyo jambo moja kukumbuka kuhusu
miti binary search ni kwamba si

1494
01:11:36,260 --> 01:11:39,800
tu kwamba kitu kwa upande wa kushoto
ni kidogo na kitu

1495
01:11:39,800 --> 01:11:41,120
haki ni kubwa zaidi.

1496
01:11:41,120 --> 01:11:44,580
Inahitaji kuwa mti mzima kwa
kushoto ni kidogo, na mti mzima

1497
01:11:44,580 --> 01:11:45,740
upande wa kulia ni kubwa zaidi.

1498
01:11:45,740 --> 01:11:55,260
>> Basi, ikiwa mimi kuweka 34 hapa juu, na kisha
Mimi kuweka 20 hapa, hivyo kwamba ni halali hivyo

1499
01:11:55,260 --> 01:11:56,970
mbali, kwa sababu 34 hapa up.

1500
01:11:56,970 --> 01:11:57,920
20 ni kwenda upande wa kushoto.

1501
01:11:57,920 --> 01:11:58,950
Hivyo kwamba ni kidogo.

1502
01:11:58,950 --> 01:12:03,640
Lakini siwezi kisha kuweka 59 hapa, kwa sababu
ingawa 59 ni juu ya haki ya 20,

1503
01:12:03,640 --> 01:12:06,140
bado ni upande wa kushoto wa 34.

1504
01:12:06,140 --> 01:12:10,760
Hivyo, pamoja na kwamba kikwazo katika akili,
njia rahisi ya pengine kutatua hili

1505
01:12:10,760 --> 01:12:14,330
tatizo ni aina tu
ya namba hizi -

1506
01:12:14,330 --> 01:12:18,720
hivyo 20, 34, 36, 52, 59, 106.

1507
01:12:18,720 --> 01:12:21,640
Na kisha kuingiza wale
kutoka kushoto kwenda kulia.

1508
01:12:21,640 --> 01:12:23,390
>> Hivyo 20 huenda hapa.

1509
01:12:23,390 --> 01:12:24,630
34 huenda hapa.

1510
01:12:24,630 --> 01:12:25,830
36 huenda hapa.

1511
01:12:25,830 --> 01:12:29,360
52, 59, 106.

1512
01:12:29,360 --> 01:12:34,730
Na wewe pia inaweza kuwa figured nje na
baadhi kuziba katika na kutambua,

1513
01:12:34,730 --> 01:12:38,830
oh, kusubiri, sina idadi ya kutosha
kujaza hii katika zaidi ya hapa.

1514
01:12:38,830 --> 01:12:42,170
Hivyo mimi haja ya reshift nini wangu
njia kumbuka ni kwenda kuwa.

1515
01:12:42,170 --> 01:12:47,490
Lakini taarifa kwamba katika fainali tatu, kama
kusoma kutoka kushoto kwenda kulia, ni katika

1516
01:12:47,490 --> 01:12:48,740
kuongeza utaratibu.

1517
01:12:48,740 --> 01:12:52,150

1518
01:12:52,150 --> 01:12:56,540
>> Basi sasa, tunataka kutangaza kile
struct ni kwenda kuwa kwa

1519
01:12:56,540 --> 01:12:58,300
nodes katika mti huu.

1520
01:12:58,300 --> 01:13:02,720
Basi je, tunahitaji katika mti binary?

1521
01:13:02,720 --> 01:13:05,830
Hivyo tuna thamani ya aina
int, hivyo baadhi ya thamani int.

1522
01:13:05,830 --> 01:13:07,220
Sijui nini sisi inayoitwa
katika ufumbuzi -

1523
01:13:07,220 --> 01:13:08,500
int n.

1524
01:13:08,500 --> 01:13:13,570
Tunahitaji pointer kwa mtoto wa kushoto
na pointer kwa mtoto wa kulia.

1525
01:13:13,570 --> 01:13:17,540
Hivyo ni kwenda kwa kuangalia kama hii.

1526
01:13:17,540 --> 01:13:20,510
Na kutakuwa na kweli kuangalia kabla ya
lini doubly-wanaohusishwa

1527
01:13:20,510 --> 01:13:25,090
orodha ya mambo, hivyo taarifa -

1528
01:13:25,090 --> 01:13:27,860
Mimi nina kwenda na kitabu yote
njia ya nyuma chini ya tatizo 11.

1529
01:13:27,860 --> 01:13:30,980

1530
01:13:30,980 --> 01:13:36,390
>> Hivyo taarifa inaonekana kufanana na hii,
ila sisi tu kutokea kwa kuwaita hawa

1531
01:13:36,390 --> 01:13:38,590
majina tofauti.

1532
01:13:38,590 --> 01:13:41,440
Bado tuna integer
thamani na kuyatumia mbili.

1533
01:13:41,440 --> 01:13:44,850
Ni kwamba tu badala ya kutibu
kuyatumia kama akizungumzia jambo la pili

1534
01:13:44,850 --> 01:13:47,955
na kitu uliopita, sisi ni kutibu
kuyatumia kwa uhakika na mtoto wa kushoto

1535
01:13:47,955 --> 01:13:49,205
na mtoto wa kulia.

1536
01:13:49,205 --> 01:13:57,372

1537
01:13:57,372 --> 01:13:57,860
OK.

1538
01:13:57,860 --> 01:13:59,650
Hivyo kwamba ni struct yetu nodi.

1539
01:13:59,650 --> 01:14:03,920
Na sasa, kazi tu tunahitaji
kutekeleza kwa hii ni tindanga, ambayo

1540
01:14:03,920 --> 01:14:08,320
tunataka kwenda juu ya mti, uchapishaji
nje maadili ya mti katika utaratibu.

1541
01:14:08,320 --> 01:14:15,241
>> Ili kuangalia hapa, tunataka unataka magazeti
nje 20, 34, 36, 52, 59, na 106.

1542
01:14:15,241 --> 01:14:17,970
Je, sisi kukamilisha kwamba?

1543
01:14:17,970 --> 01:14:18,890
Hivyo ni pretty sawa.

1544
01:14:18,890 --> 01:14:22,910
Kama aliona katika mtihani zamani tatizo
kwamba alitaka magazeti nje

1545
01:14:22,910 --> 01:14:25,940
mti mzima kwa koma katika kati ya
kila kitu, ni kweli hata

1546
01:14:25,940 --> 01:14:27,320
rahisi zaidi kuliko hiyo.

1547
01:14:27,320 --> 01:14:30,950
Hivyo hapa ni ufumbuzi.

1548
01:14:30,950 --> 01:14:33,110
Hii ilikuwa kwa kiasi kikubwa rahisi
kama alifanya hivyo recursively.

1549
01:14:33,110 --> 01:14:36,650
Sijui kama kuna mtu alijaribu
kufanya hivyo iteratively.

1550
01:14:36,650 --> 01:14:38,340
>> Lakini kwanza, tuna kesi yetu ya msingi.

1551
01:14:38,340 --> 01:14:39,660
Nini kama mzizi ni null?

1552
01:14:39,660 --> 01:14:40,610
Kisha tuko tu kwenda na kurudi.

1553
01:14:40,610 --> 01:14:42,300
Hatutaki magazeti kitu chochote.

1554
01:14:42,300 --> 01:14:45,940
Mwingine tunakwenda tindanga
recursively chini.

1555
01:14:45,940 --> 01:14:48,140
Magazeti nzima kushoto subtree.

1556
01:14:48,140 --> 01:14:51,440
Hivyo magazeti kila kitu kidogo
kuliko thamani wangu wa sasa.

1557
01:14:51,440 --> 01:14:53,930
Na basi mimi nina kwenda magazeti mwenyewe.

1558
01:14:53,930 --> 01:14:57,310
Na kisha mimi nina kwenda recurse chini yangu
nzima haki ya subtree, hivyo kila kitu

1559
01:14:57,310 --> 01:14:58,810
zaidi ya thamani yangu.

1560
01:14:58,810 --> 01:15:03,870
Na hii ni kwenda magazeti
kila kitu katika utaratibu.

1561
01:15:03,870 --> 01:15:05,860
Maswali juu ya jinsi hii kweli
kutimiza hiyo?

1562
01:15:05,860 --> 01:15:09,892

1563
01:15:09,892 --> 01:15:12,545
>> Watazamaji: Nina swali
juu ya [inaudible].

1564
01:15:12,545 --> 01:15:15,090

1565
01:15:15,090 --> 01:15:23,550
>> Rob BOWDEN: Hivyo njia moja ya inakaribia
tatizo lolote kujirudia ni kufikiri tu

1566
01:15:23,550 --> 01:15:26,275
kuhusu hilo kama una kufikiri
juu ya mambo yote kona kesi.

1567
01:15:26,275 --> 01:15:32,150

1568
01:15:32,150 --> 01:15:38,110
Hivyo kufikiria kwamba tunataka
magazeti mti chote.

1569
01:15:38,110 --> 01:15:42,030
Hivyo wote sisi ni kwenda kuzingatia
ni node fulani -

1570
01:15:42,030 --> 01:15:43,740
36.

1571
01:15:43,740 --> 01:15:47,420
wito kujirudia, sisi kujifanya
wale tu kazi.

1572
01:15:47,420 --> 01:15:54,000
Hivyo hapa, wito huu kujirudia kwa
tindanga, sisi bila hata kufikiria

1573
01:15:54,000 --> 01:15:58,640
kuhusu hilo, tu apitaye kushoto
tatu, kufikiria kwamba tayari Prints 20

1574
01:15:58,640 --> 01:16:00,730
na 34 kwa ajili yetu.

1575
01:16:00,730 --> 01:16:03,350
Na wakati sisi hatimaye recursively
kuwaita tindanga juu ya

1576
01:16:03,350 --> 01:16:07,890
haki, ambayo kwa usahihi magazeti
52, 59, na 106 kwa ajili yetu.

1577
01:16:07,890 --> 01:16:13,620
>> Hivyo kutokana na kwamba hii inaweza magazeti 20, 34, na
wengine wanaweza magazeti 52, 59, 108,

1578
01:16:13,620 --> 01:16:17,180
wote tunahitaji kuwa na uwezo wa kufanya ni magazeti
wenyewe katika katikati ya kwamba.

1579
01:16:17,180 --> 01:16:21,250
Hivyo magazeti kila kitu mbele yetu.

1580
01:16:21,250 --> 01:16:27,710
Magazeti wenyewe, hivyo magazeti node sasa
36, printf mara kwa mara, na kisha

1581
01:16:27,710 --> 01:16:31,170
magazeti kila kitu baada ya sisi.

1582
01:16:31,170 --> 01:16:32,730
>> DAVID J. Malan: Hii ni pale ambapo kujirudia
anapata kweli ni nzuri.

1583
01:16:32,730 --> 01:16:36,270
Ni hatua hii ya ajabu ya imani ambapo
kufanya tiniest kidogo ya kazi.

1584
01:16:36,270 --> 01:16:38,460
Na kisha basi mtu
mwingine kufanya mapumziko.

1585
01:16:38,460 --> 01:16:40,180
Na kwamba mtu mwingine
ni, hazijaingizwa, wewe.

1586
01:16:40,180 --> 01:16:44,260

1587
01:16:44,260 --> 01:16:48,360
Hivyo kwa pointi kubwa brownie, kama
kitabu juu ya maswali -

1588
01:16:48,360 --> 01:16:50,530
>> Rob BOWDEN: On maswali?

1589
01:16:50,530 --> 01:16:53,490
>> DAVID J. Malan: Na chini kidogo kwa
idadi, haina mtu yeyote kujua ambapo

1590
01:16:53,490 --> 01:16:55,190
namba hizi kuja kutoka?

1591
01:16:55,190 --> 01:16:56,610
>> Rob BOWDEN: Nina halisi hakuna wazo.

1592
01:16:56,610 --> 01:16:59,794
>> DAVID J. Malan: Wao kuonekana
katika jaribio.

1593
01:16:59,794 --> 01:17:01,150
>> Watazamaji: Je wao idadi hiyo?

1594
01:17:01,150 --> 01:17:01,910
>> DAVID J. Malan: Wale idadi.

1595
01:17:01,910 --> 01:17:03,260
Pasaka kidogo mayai.

1596
01:17:03,260 --> 01:17:08,100
Hivyo kwa wale wa wewe kuangalia online katika
nyumbani, kama unaweza kutuambia kupitia barua pepe kwa

1597
01:17:08,100 --> 01:17:12,680
heads@CS50.net nini maana ya
haya mara kwa mara idadi sita ni

1598
01:17:12,680 --> 01:17:18,560
katika Quiz 1, sisi akufungulieni ninyi
kwa makini ajabu katika mwisho

1599
01:17:18,560 --> 01:17:21,610
hotuba na dhiki mpira.

1600
01:17:21,610 --> 01:17:25,460

1601
01:17:25,460 --> 01:17:27,790
Nice, hila.

1602
01:17:27,790 --> 01:17:29,570
>> Rob BOWDEN: Maswali mwisho
kuhusu jambo lolote juu ya jaribio?

1603
01:17:29,570 --> 01:17:32,608