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>> [Daqq tal-mużika]

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>> ROB BODEN: Kull dritt.

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Għalhekk, l-ewwel ħaġa l-ewwel, ta 'video
minn wiċċ familjari.

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>> [VIDEO Daqq]

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>> -Id-dritt.

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Dan huwa CS50, u dan huwa
il-bidu ta 'tliet ġimgħat.

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Jien sorry I ma jista 'jkun hemm miegħek
llum, iżda ippermettili jintroduċu

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Stess Rob Boden CS50 tal.

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>> [Video daqq END]

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>> [Applause U Cheers]

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>> ROB BODEN: Il filmografija fl
li l-video huwa meraviljuż.

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Kull dritt.

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Allura l-ewwel, hemm lunch ieħor.

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Huwa għada fil 01:15.

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M'hemm l-ebda ikla din il-ġimgħa.

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Huwa ma Quora.

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U Tommy mhux hawn s'issa, iżda wieħed mill-
il-poplu hemm eks CF ras,

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Tommy McWilliam.

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Hekk hu gost Guy.

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Għandek ġejjin.

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>> Kull dritt.

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Allura aħħar ġimgħa, bdejna tkissir apparti
dwar dak string hija verament.

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Imxejna magħrufa mill-bidu li
huwa sekwenza ta 'karattri.

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Iżda aħħar ġimgħa, aħna delved fil-fatt
li dak li huwa verament sekwenza ta '

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karattri, ukoll, issa għandna
arrays ta 'karattri.

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U nafu li string, huwa firxa
ta 'karattri, fl-aħħar nett,

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aħna għandna dan byte null speċjali, dan
backslash 0, li jindika t-tmiem ta '

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l-sekwenza.

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>> U għalhekk string firxa ta '
karattri, imma aħna jista 'jkollu aktar minn

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biss firxa ta 'karattri,
nistgħu jkollhom firxa ta 'kwalunkwe

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tip ta 'ħaġa li rridu.

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Għalhekk, jekk inti recall mill-aħħar ġimgħa, il-
Etajiet programm li David introdotti

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verament malajr.

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Allura l-ewwel ħaġa li aħna qed tmur biex tagħmel hu
issaqsi lill-utent għal integer, il-

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numru ta 'nies fil-kamra.

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Ladarba għandna li integer,
aħna qed tiddikjara firxa.

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00:02:01,260 --> 00:02:02,890
Avviż dan sintassi bracket.

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00:02:02,890 --> 00:02:04,540
Int ser jidraw dan.

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>> Allura aħna qed tiddikjara firxa ta 'numri interi
imsejħa etajiet, u hemm n

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interi f'dan array.

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Allura dan il-mudell dritt hawn, dan int 4
i egwali għal 0, i huwa inqas minn n, i plus

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plus, li huwa wkoll se tkun mudell
li ikollok ħafna użati biex.

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Minħabba li pjuttost ħafna kif int
dejjem se jtenni fuq arrays.

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Mela ftakar li n hija l-
tul ta 'firxa tagħna.

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U hekk hawn, aħna ripetutament tistaqsi
għall-età ta 'persuna i fil-kamra.

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>> Wara dan, aħna jinżlu, u għal kwalunkwe
raġuni arbitrarja, aħna mbagħad

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jistampa kemm qodma dawn qed tmur
tkun sena minn issa.

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U t-tmexxija dak il-programm, ejja
jagħmlu etajiet, dot etajiet mmejla.

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Allura numru ta 'nies fil-kamra,
ejja ngħidu hemm tlieta.

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U jgħidu, l-ewwel persuna tkun 13,
jmiss huwa 26, u l-aħħar huwa 30.

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Mela allura dan ser jtenni matul dawk it-tliet
nies, jistampa 14, 27, u 31.

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>> Mela ftakar li meta aħna jiddikjaraw
firxa ta 'daqs n, l-indiċi f'dik

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firxa, il-firxa għandha valuri u
indiċi 0, 1, 2, it-triq kollha

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sa n minus 1.

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Allura meta aħna qal kien hemm tliet persuni
fil-kamra, u npoġġux fil hawn

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l-ewwel iterazzjoni permezz ta 'dan
loop, i se tkun 0.

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Allura fl-indiċi 0.

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Aħna tassenja l-ewwel
età l-utent jidħol.

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Imbagħad fil-wieħed li jmiss, aħna qed jidħlu fil-
tieni n-utent jidħol, u b'mod

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jmiss għal tnejn, l-aħħar n.

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>> Allura avviż li firxa ta 'daqs
tlieta ma jkollhom xejn

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fl-indiċi tlieta.

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Dan mhux validu.

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Kull dritt.

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Allura, li tmur lura hawn.

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Allura issa li aħna ħadthom ttrattati arrays,
għandna xi familjarità.

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Issa aħna qed tmur biex jimxu fuq kmand
argumenti linja, li ser ikunu

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pretty rilevanti għal dan is-sett problema.

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>> Allura sa issa, kull meta inti ħadthom
ddikjarat funzjoni prinċipali tiegħek, konna

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qal null prinċipali int.

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Allura vojt ifisser biss li
aħna ma tgħaddi ebda

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argumenti għal din il-funzjoni.

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Issa aħna qed tmur biex tara li prinċipali
tista 'tieħu xi argumenti.

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Here we jsejħulhom int argc
u parentesi ARGV string.

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Il-parentesi, għal darb'oħra, li jindika
li aħna qed jittrattaw ma 'arrays.

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So here, brackets ARGV string, aħna qed
jittrattaw ma 'firxa ta' kordi.

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Allura argc, li għaddej biex jindikaw
kemm argumenti konna

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mgħoddi lill dan il-programm.

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U biex tara dak li jfisser,
ejja jagħlqu dan.

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>> OK.

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Allura sa issa, aħna ħadthom run kull
programm bħal etajiet dot mmejla.

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Nistgħu wkoll, fil-linja tal-kmand, passat
jgħaddu l-argumenti, u b'hekk it-terminu, l-iggwidar

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argumenti linja.

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Allura l-ewwel argument, bonjour dinja.

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Allura hawnhekk, argc ikun tlieta.

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Hu l-għadd tal-argumenti
fil-linja tal-kmand.

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Argc huwa dejjem anqas 1, peress dot
mmejla etajiet, hija stess, jgħodd bħala waħda mill-

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l-argumenti linja tal-kmand.

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>> Imbagħad bonjour hija l-ewwel.

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Jekk etajiet dot mmejla huwa l-0, allura
bonjour hija l-ewwel, u fid-dinja huwa l-

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tieni argument linja tal-kmand.

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Allura l-ARGV string, aħna qed tmur biex tara,
fih il-kordi, dot slash

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etajiet, hello, u fid-dinja.

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U, b'talba David, aħna qed tmur
tilgħab video introduzzjoni li.

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>> [VIDEO Daqq]

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>> -Sa issa fil-programmi Imxejna
miktub, konna tiddikjara

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prinċipali null prinċipali kif int.

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U dan il-ħin, li null għandha
sempliċiment tispeċifika li l-

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programm ma tieħu kwalunkwe
argumenti linja tal-kmand.

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Fi kliem ieħor, meta utent runs
programm, hu jew hi jista 'jipprovdi kmand

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argumenti linja billi tikteb addizzjonali
kliem jew frażijiet wara tal-programm

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isem fil-prompt.

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>> Ukoll, jekk inti tixtieq program tiegħek biex
jieħdu argumenti linja tal-kmand, wieħed jew

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00:06:06,550 --> 00:06:10,540
aktar kliem bħal dawn, għandna bżonn biex jissostitwixxu
null ma 'koppja ta' argumenti.

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Mela ejja tagħmel dan.

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Inkludi CS50.h.

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Inkludi io.h. standard

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Prinċipali Int.

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U issa, minflok null, jien ser
jispeċifika int imsejħa argc, u

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firxa ta 'kordi imsejħa ARGV.

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Issa, argc u ARGV huma
sempliċiment konvenzjonijiet.

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>> Nistgħu sejħu dawn l-argumenti
xejn aktar li rridu.

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Imma dak li huwa importanti huwa li argc hija
ta int għaliex, skond id-definizzjoni, huwa

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tmur fih il-kont argument, il-
numru ta 'kliem b'kollox li l-

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utent ittajpjat fil tiegħu jew tagħha fil-pront.

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ARGV, sadanittant, argument vector, huwa
ser fil-fatt tkun array ħażna

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kollha tal-kliem li l-utent ikollu
ittajpjat fuq tiegħu jew tagħha fil-pront.

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>> Ejja tipproċedi biex tagħmel xi ħaġa issa
ma 'wieħed jew aktar minn dawn

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argumenti linja tal-kmand.

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00:06:55,660 --> 00:07:00,070
B'mod partikolari, ejja imorru quddiem u print
kwalunkwe kelma t-tipi utent

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00:07:00,070 --> 00:07:03,960
wara l-isem tal-programm
fil-prompt.

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00:07:03,960 --> 00:07:04,730
Bracket Open.

128
00:07:04,730 --> 00:07:06,240
Parentesi magħluqa.

129
00:07:06,240 --> 00:07:10,510
Mija printf backslash iu comma.

130
00:07:10,510 --> 00:07:14,550
U issa I bżonn li tgħid printf liema valur
biex plagg fil dik placeholder.

131
00:07:14,550 --> 00:07:18,600
Irrid li l-ewwel kelma li l-utent ikollu
ittajpjat wara isem tal-programm,

132
00:07:18,600 --> 00:07:23,130
u għalhekk jien ser tispeċifika
ARGV bracket 1, qrib

133
00:07:23,130 --> 00:07:24,830
parentesi, virgola.

134
00:07:24,830 --> 00:07:27,290
>> Issa, għaliex bracket 1 u mhux bracket 0?

135
00:07:27,290 --> 00:07:30,990
Ukoll, jirriżulta, maħżuna awtomatikament
fil ARGV 0 se tkun l-

136
00:07:30,990 --> 00:07:32,620
Isem attwali programm.

137
00:07:32,620 --> 00:07:36,180
Allura l-ewwel kelma li t-tipi utent
wara l-isem tal-programm huwa, minnu

138
00:07:36,180 --> 00:07:38,990
konvenzjoni, se tkun
maħżuna ARGV 1.

139
00:07:38,990 --> 00:07:42,380
Ejja issa jikkompilaw u
run dan il-programm.

140
00:07:42,380 --> 00:07:47,780
>> Jagħmlu ARGV 0, dot slash ARGV 0.

141
00:07:47,780 --> 00:07:50,520
U issa kelma bħal bonjour.

142
00:07:50,520 --> 00:07:51,670
Ikteb.

143
00:07:51,670 --> 00:07:53,520
U hemm aħna għandna hija, bonjour.

144
00:07:53,520 --> 00:07:55,750
>> [Video daqq END]

145
00:07:55,750 --> 00:07:57,000
>> ROB BODEN: Kull dritt.

146
00:07:57,000 --> 00:07:59,380

147
00:07:59,380 --> 00:08:01,230
Agħlaq din.

148
00:08:01,230 --> 00:08:16,730
Allura tieħu ħarsa lejn dak il-programm li
aħna biss introdotti lilna, ukoll, biss

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00:08:16,730 --> 00:08:24,710
li juru, jekk aħna istampar ARGV 0, jagħmlu, issa
x'inhu, ARGV 0, dot slash ARGV 0.

150
00:08:24,710 --> 00:08:30,440
Allura, kif mistenni, huwa istampar l-
isem tal-programm, peress ARGV 0 hija

151
00:08:30,440 --> 00:08:32,970
dejjem se tkun il-
isem tal-programm.

152
00:08:32,970 --> 00:08:35,640
Imma ejja nagħmlu xi ħaġa ta '
daqsxejn aktar interessanti.

153
00:08:35,640 --> 00:08:42,080
>> Allura fis-sett problema, inti ser tkun
introdott biex din il-funzjoni, atoi.

154
00:08:42,080 --> 00:08:44,440
Allura dak li nużaw atoi għall?

155
00:08:44,440 --> 00:08:48,550
Li għaddej biex jikkonverti
string għal integer.

156
00:08:48,550 --> 00:08:53,280
Hekk jekk I jgħaddu l-string, wieħed tnejn tlieta,
li atoi, li ser tikkonverti dak

157
00:08:53,280 --> 00:08:56,910
għall-eqreb numru sħiħ, wieħed tnejn tlieta.

158
00:08:56,910 --> 00:09:01,480
Allura aħna qed tmur biex jikkonvertu l-ewwel
kmand argument linja li integer,

159
00:09:01,480 --> 00:09:05,690
u mbagħad biss print li numru sħiħ.

160
00:09:05,690 --> 00:09:09,680
>> Allura bażikament, aħna qed tip ta '
reimplementing getint, biss il-

161
00:09:09,680 --> 00:09:12,350
integer hija mdaħħla fil-kmand
linja minflok fil-programm

162
00:09:12,350 --> 00:09:14,560
interattiv.

163
00:09:14,560 --> 00:09:23,170
Mela allura, jagħmlu ARGV 0, ejja nagħmlu
fil hawn, u tagħlaq dik.

164
00:09:23,170 --> 00:09:27,670
Allura running ARGV 0, u ejja jidħlu fil-
numru sħiħ, wieħed tnejn tlieta erba wieħed tnejn.

165
00:09:27,670 --> 00:09:30,840
Għalhekk ser jistampaw il-numru sħiħ, wieħed
tnejn tlieta erba wieħed tnejn.

166
00:09:30,840 --> 00:09:35,500
Hemm xi irqaqat li atoi li
dan ser tieqaf kura dwar xi ħaġa

167
00:09:35,500 --> 00:09:39,040
lil hinn minn karattru numeriku valida,
iżda li ma jimpurtax.

168
00:09:39,040 --> 00:09:42,870
>> Allura dak li taħseb jiġri
jekk nagħmel dan?

169
00:09:42,870 --> 00:09:45,520

170
00:09:45,520 --> 00:09:47,050
Tort Segmentazzjoni.

171
00:09:47,050 --> 00:09:50,410
Allura għaliex huwa li?

172
00:09:50,410 --> 00:09:56,060
Jekk inti tħares lura lejn programm tagħna, aħna qed
konverżjoni ARGV 1, l-ewwel argument

173
00:09:56,060 --> 00:09:59,610
wara l-isem tal-programm, għal numru sħiħ.

174
00:09:59,610 --> 00:10:03,350
Imma m'hemm l-ebda argument għadda
wara l-isem tal-programm.

175
00:10:03,350 --> 00:10:08,060
Allura hawn, naraw li dan huwa Buggy
programm, peress li, jekk nippruvaw run

176
00:10:08,060 --> 00:10:10,530
mingħajr ebda argumenti,
se biss crash.

177
00:10:10,530 --> 00:10:16,950
>> Allura ieħor mudell komuni tkun taf tara
huwa xi ħaġa simili, jekk argc huwa inqas

178
00:10:16,950 --> 00:10:21,100
minn tnejn, li jindika li ma kienx hemm
inqas l-isem programm u

179
00:10:21,100 --> 00:10:29,100
ewwel argument, allura aħna ser nagħmlu xi ħaġa
bħal printf, mhux biżżejjed

180
00:10:29,100 --> 00:10:31,190
argumenti linja tal-kmand.

181
00:10:31,190 --> 00:10:33,170
Li probabbilment mhix waħda tajba għall-istampar,
huwa probabbilment xi ħaġa, bħal

182
00:10:33,170 --> 00:10:35,440
għandek tidħol integer
fil-linja tal-kmand.

183
00:10:35,440 --> 00:10:37,450
I ser biss jispiċċaw hemmhekk.

184
00:10:37,450 --> 00:10:39,600
U mbagħad jirritornaw 1.

185
00:10:39,600 --> 00:10:44,740
Mela ftakar li fl-aħħar ta 'tagħna
programm, jekk nerġgħu lura 0, dik it-tip ta '

186
00:10:44,740 --> 00:10:47,060
jindika suċċess.

187
00:10:47,060 --> 00:10:50,940
U prinċipali wkoll awtomatikament
prospetti 0 jekk inti ma.

188
00:10:50,940 --> 00:10:55,800
>> Allura hawn, aħna qed retuning 1 biex jindikaw
li li mhux suċċess.

189
00:10:55,800 --> 00:11:01,000
U inti tista 'tmur lura xi trid,
biss, 0 jindika suċċess, u

190
00:11:01,000 --> 00:11:03,390
kull ħaġ'oħra jindika falliment.

191
00:11:03,390 --> 00:11:04,855
Mela ejja run din il-verżjoni ta 'affarijiet.

192
00:11:04,855 --> 00:11:12,880

193
00:11:12,880 --> 00:11:16,600
Allura issa, jekk aħna ma jidħol kmand tal-linja
argument, dan ser jgħidlek b'mod korrett

194
00:11:16,600 --> 00:11:18,290
us, mhux biżżejjed linja tal-kmand.

195
00:11:18,290 --> 00:11:20,610
Ma finitura is-sentenza.

196
00:11:20,610 --> 00:11:24,950
Else, jekk aħna attwalment tgħaddiha waħda,
jista 'jtemm il-programm.

197
00:11:24,950 --> 00:11:27,920
Allura dan huwa kif inti tuża argc fl
sabiex jivvalidaw in-numru ta '

198
00:11:27,920 --> 00:11:30,630
argumenti kmand linja li
huma attwalment mgħoddija.

199
00:11:30,630 --> 00:11:39,360
>> Mela ejja jagħmlu dan il-programm daqsxejn aktar
ikkumplikata, u ħarsa lejn it-tieni

200
00:11:39,360 --> 00:11:42,180
iterazzjoni ta 'affarijiet.

201
00:11:42,180 --> 00:11:46,310
Allura issa, aħna mhux biss istampar tal-
ewwel argument linja tal-kmand.

202
00:11:46,310 --> 00:11:51,210
Hawnhekk, aħna qed mtennija minn partijiet ugwali i int
0, i huwa inqas minn argc, i plus

203
00:11:51,210 --> 00:11:55,280
plus, u l-istampar ARGV, indiċi i.

204
00:11:55,280 --> 00:11:59,300
Allura dan il-mudell, għal darb'oħra, dan huwa l-istess
mudell bħal qabel, ħlief minflok

205
00:11:59,300 --> 00:12:02,600
ta 'sejħa tal-varjabbli
n, aħna qed tuża argc.

206
00:12:02,600 --> 00:12:09,520
>> Allura dan huwa mtennija fuq kull indiċi
fil-firxa, u l-istampar kull

207
00:12:09,520 --> 00:12:11,910
element f'dak array.

208
00:12:11,910 --> 00:12:20,300
U għalhekk, meta aħna run dan il-programm, ukoll,
I ma tidħol fi kwalunkwe linja tal-kmand

209
00:12:20,300 --> 00:12:22,540
argumenti, għalhekk biss prints
l-isem tal-programm.

210
00:12:22,540 --> 00:12:26,053
Jekk I tidħol mazz ta 'affarijiet, inneħħu
print wieħed, kull wieħed fuq linja tagħha stess.

211
00:12:26,053 --> 00:12:31,213

212
00:12:31,213 --> 00:12:32,210
>> OK.

213
00:12:32,210 --> 00:12:34,770
Mela ejja tagħti dan il-pass wieħed ulterjuri.

214
00:12:34,770 --> 00:12:38,890
U minflok ta 'stampar kull argument
fuq il-linja tagħha stess, ejja jistampaw kull

215
00:12:38,890 --> 00:12:42,590
karattru ta 'kull argument
fuq il-linja tagħha stess.

216
00:12:42,590 --> 00:12:46,700
Mela ftakar li ARGV hija
firxa ta 'kordi.

217
00:12:46,700 --> 00:12:50,960
Allura dak li huwa string, iżda
firxa ta 'karattri?

218
00:12:50,960 --> 00:12:57,140
Allura dan ifisser li ARGV huwa verament
firxa ta 'firxa ta' karattri.

219
00:12:57,140 --> 00:13:04,920
Allura jieħdu vantaġġ ta 'dan,
ejja jinjora dan għal issa.

220
00:13:04,920 --> 00:13:08,190
Ejja biss tikkunsidra l-ARGV string 0.

221
00:13:08,190 --> 00:13:14,170
>> Allura jekk aħna tixtieq li tressaq kull karattru ta '
ARGV 0 fuq il-linja tagħha stess, allura nixtieq

222
00:13:14,170 --> 00:13:19,500
jagħmlu l-mudell aħna qed jintużaw biex, i huwa
inqas mit-tul tal-firxa,

223
00:13:19,500 --> 00:13:23,990
li hawn, huwa strlen ta ', li
mhux dak I trid tagħmel, string

224
00:13:23,990 --> 00:13:26,450
s ugwali ARGV 0.

225
00:13:26,450 --> 00:13:30,390
Hekk i huwa inqas mit-tul ta 'tagħna
array, li f'dan il-każ huwa array

226
00:13:30,390 --> 00:13:34,410
ta 'karattri, i plus plus.

227
00:13:34,410 --> 00:13:41,040
U hekk, kif rajna aħħar ġimgħa, huwa ideali
jekk nimxu li strlen barra

228
00:13:41,040 --> 00:13:45,210
tal-kundizzjoni, peress li n se jkun li żżid
l strlen ta 'kull darba immorru

229
00:13:45,210 --> 00:13:47,720
permezz tal-linja, u huwa
mhux se jinbidlu.

230
00:13:47,720 --> 00:13:50,230
Allura aħna ser tissettja ugwali għal n hawn fuq.

231
00:13:50,230 --> 00:13:54,260

232
00:13:54,260 --> 00:13:55,170
>> OK.

233
00:13:55,170 --> 00:14:01,320
Allura issa, aħna qed mtennija fuq
kull indiċi fil-firxa.

234
00:14:01,320 --> 00:14:05,630
U hekk, jekk irridu li jistampaw kull
karattru f'dak array, mija c huwa

235
00:14:05,630 --> 00:14:06,880
il-bandiera irridu li jużaw
għall-karattri.

236
00:14:06,880 --> 00:14:10,750

237
00:14:10,750 --> 00:14:19,770
U issa i bracket se tkun l-
spag, karattru indiċi i, hekk jekk l-

238
00:14:19,770 --> 00:14:20,970
string kienu bonjour.

239
00:14:20,970 --> 00:14:27,530
allura s 0 se tkun h, i bracket
1 se jkun e, u l-bqija.

240
00:14:27,530 --> 00:14:30,800
>> Allura issa rridu li jgħaqqdu
dawn iż-żewġ affarijiet.

241
00:14:30,800 --> 00:14:35,440
Aħna tixtieq li jistampaw kull karattru
ta 'kull argument linja tal-kmand.

242
00:14:35,440 --> 00:14:38,950
Allura aħna qed tmur biex ikollhom
a nested għal loop.

243
00:14:38,950 --> 00:14:47,480
U konvenzjonalment, l-ewwel counter
qed i, il-li jmiss se tkun j, n

244
00:14:47,480 --> 00:14:54,450
se jkun il-strlen ta 'i ARGV, i
huwa inqas minn n, i plus plus.

245
00:14:54,450 --> 00:14:59,150

246
00:14:59,150 --> 00:15:06,870
U issa minflok ta 'stampar i ARGV, hekk
ARGV bracket i se indiċi -

247
00:15:06,870 --> 00:15:14,280
li għaddej biex tkun il-linja tal-kmand i-th
argument, ARGV i, j huwa ser

248
00:15:14,280 --> 00:15:16,925
tkun il-karattru jth ta
l-argument i-th.

249
00:15:16,925 --> 00:15:20,580

250
00:15:20,580 --> 00:15:24,810
I ser teħles minn dan up hawn issa
peress li aħna poġġih f'dak loop.

251
00:15:24,810 --> 00:15:33,900
Allura huwa ekwivalenti għal string s ugwali
ARGV i, u mbagħad parentesi s j.

252
00:15:33,900 --> 00:15:36,980
>> Well, aħna ma bżonn li tiddikjara
dan il-varjabbli s.

253
00:15:36,980 --> 00:15:44,530
Minflok, aħna ser biss jgħaqqdu dawn
tnejn fis-dak li kellna, ARGV i, j.

254
00:15:44,530 --> 00:15:45,780
>> SPEAKER 1: [inaudible].

255
00:15:45,780 --> 00:15:48,850

256
00:15:48,850 --> 00:15:49,680
>> ROB BODEN: sejħa Tajba.

257
00:15:49,680 --> 00:15:52,936
Allura dan huwa miksur.

258
00:15:52,936 --> 00:15:55,510
Jekk I attwalment dam, nixtiequ
jkunu realizzati dan.

259
00:15:55,510 --> 00:16:01,210
Allura l-counter I jimpurtahom
f'dan partikolari għall-

260
00:16:01,210 --> 00:16:05,410
loop hija j, l iterator.

261
00:16:05,410 --> 00:16:08,560
Allura inti run fis kwistjonijiet,
probabbilment loop infinita, jekk aħna

262
00:16:08,560 --> 00:16:09,540
ma tkunx iffissata dik.

263
00:16:09,540 --> 00:16:12,220
C'est pourquoi aħna qed wkoll jitkellem
dwar debugging illum.

264
00:16:12,220 --> 00:16:13,120
>> OK.

265
00:16:13,120 --> 00:16:15,240
Mela ejja run dan il-programm.

266
00:16:15,240 --> 00:16:21,200
U ejja attwalment żid printf separata
dritt hawn li se biss print

267
00:16:21,200 --> 00:16:27,480
linja oħra, peress li dan ifisser meta aħna
tmexxi l-programm, se jkun hemm xi vojt

268
00:16:27,480 --> 00:16:31,830
linja bejn kull karattru ta '
kull argument linja tal-kmand.

269
00:16:31,830 --> 00:16:33,448
Well, aħna ser tara dak li jfisser.

270
00:16:33,448 --> 00:16:37,310

271
00:16:37,310 --> 00:16:37,790
OOP.

272
00:16:37,790 --> 00:16:39,870
Ltqajna xi bug.

273
00:16:39,870 --> 00:16:42,860
Error impliċitament li tiddikjara
funzjoni librerija strlen.

274
00:16:42,860 --> 00:16:51,630
>> Allura jmorru lura fil-programm tagħna, I
nesa li hash jinkludu string.h.

275
00:16:51,630 --> 00:16:54,240

276
00:16:54,240 --> 00:16:57,730
Allura string.h se tkun l-
fajl header li tiddikjara

277
00:16:57,730 --> 00:16:58,980
il-funzjoni strlen.

278
00:16:58,980 --> 00:17:04,650

279
00:17:04,650 --> 00:17:06,060
OK lok, hija tiġbor.

280
00:17:06,060 --> 00:17:09,109
Issa, ejja run.

281
00:17:09,109 --> 00:17:10,930
Allura dan.

282
00:17:10,930 --> 00:17:17,790
Huwa ser jistampa tagħna
isem tal-programm, bonjour dinja.

283
00:17:17,790 --> 00:17:23,510
Huwa ser jistampaw kull ħaġa, kull
karattru, fuq il-linja tagħha stess.

284
00:17:23,510 --> 00:17:24,540
OK.

285
00:17:24,540 --> 00:17:30,625
>> Mela ejja attwalment jieħdu din
pass ulterjuri.

286
00:17:30,625 --> 00:17:34,050

287
00:17:34,050 --> 00:17:39,700
U minflok jużaw string.h, ejja
jaħsbu dwar kif aħna'd jiġu implimentati tagħna stess

288
00:17:39,700 --> 00:17:41,420
funzjoni strlen.

289
00:17:41,420 --> 00:17:45,600
So I ser jagħtuk immedjatament
firma funzjoni.

290
00:17:45,600 --> 00:17:52,900
Mela ejja sejħa fil my_strlen, u huwa
ser tieħu string bħala argument,

291
00:17:52,900 --> 00:17:57,220
u qed nistennew li jirritornaw il-
tul ta 'dak string.

292
00:17:57,220 --> 00:18:03,430
Għalhekk, fejn huwa li Guy?

293
00:18:03,430 --> 00:18:04,990
Iva.

294
00:18:04,990 --> 00:18:06,740
OK.

295
00:18:06,740 --> 00:18:12,900
Sabiex tiftakar mill-slide ta 'qabel li
kien ukoll mill-aħħar ġimgħa, li

296
00:18:12,900 --> 00:18:18,890
firxa ta 'karattri, ukoll, string,
hekk ejja ngħidu li dan huwa string tagħna s.

297
00:18:18,890 --> 00:18:29,870
Hekk jekk i huwa l-sekwenza, hello, allura,
H-E-L-L-O, fil-memorja, li għaddej biex

298
00:18:29,870 --> 00:18:35,610
jkun, u allura dan backslash
0 karattru.

299
00:18:35,610 --> 00:18:39,170
>> Allura kif nistgħu tikseb it-tul ta 'i?

300
00:18:39,170 --> 00:18:43,190
Ukoll, il-trick qed tfittex dan
backlash 0 karattru, dan null

301
00:18:43,190 --> 00:18:44,380
terminatur.

302
00:18:44,380 --> 00:18:50,270
Allura l-algoritmu huwa għaddej
li tkun xi ħaġa simili ftit

303
00:18:50,270 --> 00:18:51,510
biżżejjed karattri li -

304
00:18:51,510 --> 00:18:56,180
ejja jkollhom din idejn jirrappreżentaw xi
counter, ejja sejħa dan it-tul int.

305
00:18:56,180 --> 00:19:00,060
Allura, li jibdew minn hawn, aħna qed
ser jtenni fuq string tagħna.

306
00:19:00,060 --> 00:19:04,100
>> Allura l-ewwel karattru, huwa H,
u mhuwiex lura mmejla 0, hekk

307
00:19:04,100 --> 00:19:05,170
it-tul huwa 1.

308
00:19:05,170 --> 00:19:08,050
Jtenni l-karattru li jmiss,
E, u mhuwiex backslash 0.

309
00:19:08,050 --> 00:19:09,630
Tul huwa 2.

310
00:19:09,630 --> 00:19:10,960
L, 3.

311
00:19:10,960 --> 00:19:11,850
L-4.

312
00:19:11,850 --> 00:19:13,050
O, 5.

313
00:19:13,050 --> 00:19:16,690
U fl-aħħarnett, nilħqu backslash
0, u sabiex ifisser, ukoll,

314
00:19:16,690 --> 00:19:17,780
din is-sekwenza huwa fuq.

315
00:19:17,780 --> 00:19:20,130
Mela ejja ritorn 5.

316
00:19:20,130 --> 00:19:33,630
>> Allura konkret ta 'din, minn naħa,
tul n my ikun egwali għal 0, lemin tiegħi.

317
00:19:33,630 --> 00:19:36,088
U aħna qed tmur biex jtenni -

318
00:19:36,088 --> 00:19:38,000
>> SPEAKER 1: [inaudible]

319
00:19:38,000 --> 00:19:38,640
>> ROB BODEN: Oh, rimja.

320
00:19:38,640 --> 00:19:39,870
Sejħa tajba.

321
00:19:39,870 --> 00:19:42,680
Boom.

322
00:19:42,680 --> 00:19:44,140
Allura tul n egwali għal 0.

323
00:19:44,140 --> 00:19:46,910

324
00:19:46,910 --> 00:19:58,310
Allura issa, it-tul filwaqt li s ma
istess daqs u mbagħad, backslash 0.

325
00:19:58,310 --> 00:20:04,660
Mela ftakar, dan backslash 0, huwa
karattru attwali, u dan jindika

326
00:20:04,660 --> 00:20:05,820
tmiem is-sekwenza.

327
00:20:05,820 --> 00:20:09,850
Eżatt bħal, ukoll, backslash
n huwa karattru attwali.

328
00:20:09,850 --> 00:20:14,040
Backslash 0 se jindikaw
l-aħħar ta 'sekwenza tagħna.

329
00:20:14,040 --> 00:20:15,414
I ma jridux jitqiegħdu li hemm.

330
00:20:15,414 --> 00:20:19,190

331
00:20:19,190 --> 00:20:25,620
U filwaqt li s indiċjati skond it-tul ma jkunx
ugwali għall-terminatur null, imbagħad

332
00:20:25,620 --> 00:20:27,130
aħna qed biss se inkrement tul.

333
00:20:27,130 --> 00:20:29,860

334
00:20:29,860 --> 00:20:34,880
Mela allura, fl-aħħar tal-programm tagħna,
tul huwa eventwalment ser

335
00:20:34,880 --> 00:20:37,610
jkun 5 f'dan il-każ.

336
00:20:37,610 --> 00:20:39,210
U aħna ser biss jirritorna tul.

337
00:20:39,210 --> 00:20:42,570

338
00:20:42,570 --> 00:20:43,530
>> OK.

339
00:20:43,530 --> 00:20:48,290
Allura issa stabbiliti hawn, I ma
do my_strlen.

340
00:20:48,290 --> 00:20:50,700
Ejja josservawha tagħmel ċert
kollox jimxi bla xkiel.

341
00:20:50,700 --> 00:20:55,820

342
00:20:55,820 --> 00:20:58,210
Was I tagħmel fi 2?

343
00:20:58,210 --> 00:21:00,565
Jew kien li 1?

344
00:21:00,565 --> 00:21:01,940
Li għandha tagħmel.

345
00:21:01,940 --> 00:21:02,690
Kull dritt.

346
00:21:02,690 --> 00:21:08,490
Allura dan huwa ARGV 2.

347
00:21:08,490 --> 00:21:11,585
Jaħdem bħala antiċipat, għalkemm
kien li l-waħda I ma kien fil-?

348
00:21:11,585 --> 00:21:15,060

349
00:21:15,060 --> 00:21:15,550
Iva.

350
00:21:15,550 --> 00:21:16,760
OK.

351
00:21:16,760 --> 00:21:21,820
Din il-verżjoni ta 'affarijiet ma kellux
il-linja ġdida printf wara, iżda

352
00:21:21,820 --> 00:21:22,910
ma jagħmel ebda differenza.

353
00:21:22,910 --> 00:21:23,300
OK.

354
00:21:23,300 --> 00:21:25,780
Allura ħadmu kif mistenni.

355
00:21:25,780 --> 00:21:34,750
>> Issa nistgħu anki jgħaqqdu dan il-pass wieħed
ulterjuri, fejn avviz hawn, ukoll,

356
00:21:34,750 --> 00:21:38,920
ewwel, aħna qed ħtif l strlen ta ARGV
i, u allura aħna qed mtennija fuq

357
00:21:38,920 --> 00:21:41,450
kull karattru f'dak string.

358
00:21:41,450 --> 00:21:47,480
Allura minflok tagħmel dan, dak li jekk aħna
biss jgħaqqdu din il-loġika ta 'stennija

359
00:21:47,480 --> 00:21:50,740
sakemm aħna hit backslash 0 dritt
fis dan għal loop?

360
00:21:50,740 --> 00:21:53,740

361
00:21:53,740 --> 00:22:07,490
Allura jtenni filwaqt i ARGV, j ma
backslash mhux ugwali 0.

362
00:22:07,490 --> 00:22:10,680
Mela ejja run ewwel.

363
00:22:10,680 --> 00:22:19,838

364
00:22:19,838 --> 00:22:21,180
>> Kull dritt.

365
00:22:21,180 --> 00:22:27,655
Allura hawn, din il-kundizzjoni huwa qal -

366
00:22:27,655 --> 00:22:38,090

367
00:22:38,090 --> 00:22:40,060
ejja ċar li.

368
00:22:40,060 --> 00:22:49,140
Allura issa, ħalli din tkun ARGV tagħna.

369
00:22:49,140 --> 00:22:55,290
Allura meta I biss dam dak il-programm qabel,
ARGV firxa ta 'kordi.

370
00:22:55,290 --> 00:23:03,100
U għalhekk, jekk I run ma ARGV dot slash
2, Hello dinja, allura l-ARGV

371
00:23:03,100 --> 00:23:07,650
nnifisha hija tul ta '3, għall ARGV
żero, hello, u fid-dinja.

372
00:23:07,650 --> 00:23:11,700

373
00:23:11,700 --> 00:23:19,660
>> U ġewwa ta 'kull wieħed minn dawn l-indiċi huwa,
innifsu firxa, fejn dan ser tkun

374
00:23:19,660 --> 00:23:23,780
dot, dan se jkun slash, I do not know
jekk dan kien il-direzzjoni t-tajba, I

375
00:23:23,780 --> 00:23:25,680
ma naħsibx li kien.

376
00:23:25,680 --> 00:23:30,110
A-R-V sing, jeħtieġu aktar spazju.

377
00:23:30,110 --> 00:23:32,570
Ejja maqtugħa dan array.

378
00:23:32,570 --> 00:23:38,230
Sing 0, u mbagħad backslash 0 A-R-V.

379
00:23:38,230 --> 00:23:43,160
U mbagħad diżordinat se jkun bonjour.

380
00:23:43,160 --> 00:23:45,910
Ejja ngħidu, H-E backslash 0.

381
00:23:45,910 --> 00:23:51,130
U fl-aħħarnett, W-O backslash 0.

382
00:23:51,130 --> 00:23:59,730
>> Allura l-algoritmu li aħna biss kiteb,
l nested għal-linji, dak li qed

383
00:23:59,730 --> 00:24:07,321
tagħmel huwa, aħna l-ewwel ikollhom l-
kontro i u mbagħad j.

384
00:24:07,321 --> 00:24:15,206
Dan ikun aktar faċli ma 'kodiċi fuq il-
screen, Ejja ħa mmorru lura għal dan.

385
00:24:15,206 --> 00:24:17,476
OK.

386
00:24:17,476 --> 00:24:24,600
Allura avviż li i huwa l-iterator li l-
mtennija fuq kull kmand

387
00:24:24,600 --> 00:24:25,610
argument line.

388
00:24:25,610 --> 00:24:28,870
U j huwa l-iterazzjoni iterator
fuq kull karattru li

389
00:24:28,870 --> 00:24:30,410
argument linja tal-kmand.

390
00:24:30,410 --> 00:24:46,755
Allura dak li dan printf ġewwanett qed tagħmel
huwa, għandna printf ARGV 0 0, printf

391
00:24:46,755 --> 00:24:58,680
ARGV 0 1, printf ARGV 0 2, 3 0, 0 4, 0
5, 0 6, iżda issa, ARGV 0 7 se

392
00:24:58,680 --> 00:25:00,670
backslash ugwali 0.

393
00:25:00,670 --> 00:25:05,730
>> Mela allura aħna ħruġ li għal loop,
u issa i itenni għal 1.

394
00:25:05,730 --> 00:25:10,910
U issa aħna qed tmur biex print
ARGV 1 0, ARGV 1 1 -

395
00:25:10,910 --> 00:25:17,040
ukoll, issa, peress li jien cut bonjour qasir,
ARGV 1 2 hija għal darb'oħra se tkun

396
00:25:17,040 --> 00:25:18,170
backslash 0.

397
00:25:18,170 --> 00:25:25,050
U għalhekk, inkrement i u tkompli, u
hekk, sakemm aħna jistampaw kollha

398
00:25:25,050 --> 00:25:28,580
dinja, u dawk huma tlieta linja ta 'kmand
argumenti, u aħna ser ħruġ minn

399
00:25:28,580 --> 00:25:31,670
l loop aktar imbiegħda, u
finitura programm tagħna.

400
00:25:31,670 --> 00:25:38,390

401
00:25:38,390 --> 00:25:39,640
OK.

402
00:25:39,640 --> 00:25:43,903

403
00:25:43,903 --> 00:25:46,795
>> Mela ejja jiġu lura hawn.

404
00:25:46,795 --> 00:25:49,670

405
00:25:49,670 --> 00:25:52,370
Allura inti ser jiksbu xi familjarità mal-
argumenti linja tal-kmand fuq dan

406
00:25:52,370 --> 00:25:54,460
partikolari problema stabbiliti.

407
00:25:54,460 --> 00:25:56,630
>> Issa, debugging.

408
00:25:56,630 --> 00:26:01,680
Allura inti probabilment diġà kellha tagħmel
xi debugging mal preċedenti tiegħek

409
00:26:01,680 --> 00:26:03,120
problema stabbiliti.

410
00:26:03,120 --> 00:26:08,420
U wieħed mod faċli ħafna ta 'debugging,
ewwel, ejja nħarsu lejn programm buggy.

411
00:26:08,420 --> 00:26:20,710

412
00:26:20,710 --> 00:26:23,830
Well, mixi permezz dan il-programm,
aħna qed tmur biex issaqsi lill-utent għal

413
00:26:23,830 --> 00:26:29,350
numru sħiħ, grab li integer, u mbagħad,
arbitrarju, għandna loop filwaqt li

414
00:26:29,350 --> 00:26:32,280
huwa biss se decrement
i sakemm ikun ugwali għal 10.

415
00:26:32,280 --> 00:26:35,820
Ejja biss wieħed jassumi jien jidħlu
integer akbar minn 10.

416
00:26:35,820 --> 00:26:38,700
Allura decrement i sakemm ikun ugwali għal 10.

417
00:26:38,700 --> 00:26:42,630
>> U allura għandna loop ieħor filwaqt li
li, filwaqt li i ma tkunx daqs 0, aħna qed

418
00:26:42,630 --> 00:26:44,540
se decrement i bi 3.

419
00:26:44,540 --> 00:26:49,790
Mela jekk tara l-intenzjoni tal-bug
hawnhekk, huwa li dan ser decrement i li

420
00:26:49,790 --> 00:26:57,010
tkun ta '10, u allura dan loop filwaqt li se
decrement i mill-10, 7, 4, għal 1,

421
00:26:57,010 --> 00:27:02,880
għal negattiv 2, għal negattiv 5, u l-bqija,
għall-infinit negattiva, peress i se

422
00:27:02,880 --> 00:27:05,920
fatt qatt ma ugwali 0.

423
00:27:05,920 --> 00:27:08,610
U mbagħad fl-aħħar ta 'dan il-programm,
aħna għandna l-funzjoni foo li huwa

424
00:27:08,610 --> 00:27:12,130
għaddej print out dak i.

425
00:27:12,130 --> 00:27:16,520
>> Allura dan huwa programm qasir u trivjali,
u l-bug hija ovvja,

426
00:27:16,520 --> 00:27:18,790
speċjalment wara I biss
qal dak li l-bug kien.

427
00:27:18,790 --> 00:27:24,840
Iżda l-intenzjoni hawnhekk hija, ukoll, dan jista '
attwalment look like xi tiegħek

428
00:27:24,840 --> 00:27:30,040
soluzzjonijiet minn greedy mill-aħħar
problema stabbiliti, u forsi inti għandek

429
00:27:30,040 --> 00:27:32,800
xi loop infinita fil-programm tiegħek,
u ma jkollokx idea

430
00:27:32,800 --> 00:27:34,100
x'hemm jikkawżaw.

431
00:27:34,100 --> 00:27:38,690
Allura teknika debugging utli ħafna
huwa li żżid ftit printfs

432
00:27:38,690 --> 00:27:40,180
kollha fuq kodiċi tiegħek.

433
00:27:40,180 --> 00:27:49,200
>> So here I tixtieq printf barra
ewwel loop waqt.

434
00:27:49,200 --> 00:27:53,155
U hawn irrid printf,
u jien ser biss print i.

435
00:27:53,155 --> 00:27:55,670

436
00:27:55,670 --> 00:27:58,330
I ser anki tagħmel l-ewwel filwaqt li loop, i.

437
00:27:58,330 --> 00:28:05,130

438
00:28:05,130 --> 00:28:09,040
Barra, it-tieni waqt loop.

439
00:28:09,040 --> 00:28:12,170
Għal darb'oħra, jistampa ġewwa
hawn, il-valur i.

440
00:28:12,170 --> 00:28:16,270

441
00:28:16,270 --> 00:28:17,520
U ejja run dan.

442
00:28:17,520 --> 00:28:22,620

443
00:28:22,620 --> 00:28:24,800
>> Debug slash hekk dot.

444
00:28:24,800 --> 00:28:25,610
Ikteb integer.

445
00:28:25,610 --> 00:28:28,150
Ejja nagħmlu 13.

446
00:28:28,150 --> 00:28:28,760
U boom.

447
00:28:28,760 --> 00:28:33,300
Naraw li aħna looping infinita
ġewwa tat-tieni linja waqt.

448
00:28:33,300 --> 00:28:36,305
Allura issa nafu x'inhi l-bug huwa.

449
00:28:36,305 --> 00:28:39,610

450
00:28:39,610 --> 00:28:45,610
Iżda debugging printf huwa perfettament kbira,
imma ladarba programmi tiegħek jiksbu

451
00:28:45,610 --> 00:28:50,560
itwal u aktar ikkumplikati, hemm
soluzzjonijiet aktar sofistikati għall-

452
00:28:50,560 --> 00:28:51,705
jkollna affarijiet tax-xogħol.

453
00:28:51,705 --> 00:28:52,955
Mela ejja jitneħħew dawn printfs kollha.

454
00:28:52,955 --> 00:29:06,242

455
00:29:06,242 --> 00:29:08,896
U ejja jagħmlu ċert I ma
break xejn.

456
00:29:08,896 --> 00:29:09,850
OK.

457
00:29:09,850 --> 00:29:14,180
>> Allura l-programm aħna qed tmur
li tintroduċi tissejjaħ

458
00:29:14,180 --> 00:29:16,715
GDB, għall GNU Debugger.

459
00:29:16,715 --> 00:29:21,892

460
00:29:21,892 --> 00:29:27,510
Well, attwalment, ejja tneħħi debug għall
it-tieni, u jagħmlu debug darb'oħra.

461
00:29:27,510 --> 00:29:31,420

462
00:29:31,420 --> 00:29:34,440
Well, attwalment ewwel, lezzjoni tajba
fl-argumenti linja tal-kmand.

463
00:29:34,440 --> 00:29:37,780
Avviż li dan il-kmand Clang li hija
kompilazzjoni kollox qed mgħoddija

464
00:29:37,780 --> 00:29:41,300
fil-linja tal-kmand, dawn
argumenti linja tal-kmand.

465
00:29:41,300 --> 00:29:46,250
Allura eżattament kif inti se tkun qed tuża
argumenti linja tal-kmand, kif aħna

466
00:29:46,250 --> 00:29:51,500
ma qabel, u kif inti ser fil PSET
2, li kif Clang qed jużawhom.

467
00:29:51,500 --> 00:30:00,070
>> Allura avviż li din l-ewwel bandiera, sing
ggdb3, dak li kien qal huwa, Clang,

468
00:30:00,070 --> 00:30:03,790
inti għandhom jiġbru dan il-fajl bl-
intenzjoni li aħna se eventwalment

469
00:30:03,790 --> 00:30:05,380
bżonn biex debug dan.

470
00:30:05,380 --> 00:30:13,840
Dan sakemm ikollok dak tal-bandiera,
allura nistgħu debug GDB.

471
00:30:13,840 --> 00:30:17,380
U inneħħu tiftaħ il Debugger GNU.

472
00:30:17,380 --> 00:30:22,920
>> Allura hemm ħafna ta 'kmandi
li għandek bżonn biex jidraw.

473
00:30:22,920 --> 00:30:27,100
L-ewwel waħda li inti probabilment
immedjatament bżonn huwa Run.

474
00:30:27,100 --> 00:30:28,200
Allura x'inhu Run se jagħmlu?

475
00:30:28,200 --> 00:30:30,910
Huwa ser tibda programm tagħna.

476
00:30:30,910 --> 00:30:36,180
Allura run, programm tal-bidu, il-programm
jitlob magħna għal integer, 13.

477
00:30:36,180 --> 00:30:39,170
U allura huwa looping infinita bħala
mistennija, ħlief I jitneħħew l-

478
00:30:39,170 --> 00:30:40,500
printfs, hekk aħna ma anki tara li.

479
00:30:40,500 --> 00:30:43,320

480
00:30:43,320 --> 00:30:44,600
Ħareġ normalment.

481
00:30:44,600 --> 00:30:45,850
Oh.

482
00:30:45,850 --> 00:30:48,570

483
00:30:48,570 --> 00:30:53,640
Huwa possibbli li mgeżwra l-
mod madwar, lura għall - jinjora dan.

484
00:30:53,640 --> 00:30:55,170
Assumi hija ma ħruġ normalment.

485
00:30:55,170 --> 00:30:59,500

486
00:30:59,500 --> 00:31:03,370
Hemm tweġiba kkumplikata għal dan.

487
00:31:03,370 --> 00:31:07,890
>> Allura issa, li mhux utli ħafna.

488
00:31:07,890 --> 00:31:11,480
Hekk biss running programm tagħna ġewwa ta '
dan debugger ma tgħinna fi kwalunkwe

489
00:31:11,480 --> 00:31:15,610
mod, peress li aħna seta 'biss isir
dot mmejla debug minn barra GDB.

490
00:31:15,610 --> 00:31:21,250
Allura l-kmand wieħed li
Int ser ikollok probabbilment -

491
00:31:21,250 --> 00:31:22,970
u jien ser nieqaf dan.

492
00:31:22,970 --> 00:31:25,850
Kontroll d jew nieqaf, kemm ix-xogħol.

493
00:31:25,850 --> 00:31:29,550
Mela ejja tiftaħ it up again.

494
00:31:29,550 --> 00:31:31,130
>> Ieħor kmand li inti probabilment
immedjatament jridu

495
00:31:31,130 --> 00:31:33,600
jidraw huwa Break.

496
00:31:33,600 --> 00:31:37,120
Allura aħna ser jiksru fuq ewlenija għal issa,
u mbagħad I ser jispjegaw dan.

497
00:31:37,120 --> 00:31:41,010

498
00:31:41,010 --> 00:31:46,370
Well, hawn naraw waqqafna breakpoint
fuq din il-linja fil debug.c.

499
00:31:46,370 --> 00:31:50,160
Allura dak break ifisser huwa li meta I
tip run, il-programm se

500
00:31:50,160 --> 00:31:53,560
tkompli taħdem sakemm
I hit breakpoint.

501
00:31:53,560 --> 00:31:59,390
Allura meta I hit run, il-programm jibda,
u mbagħad pawżi hekk kif

502
00:31:59,390 --> 00:32:01,940
jidħol l-funzjoni prinċipali.

503
00:32:01,940 --> 00:32:06,930
Break prinċipali se tkun xi ħaġa
inti pretty komunement tagħmel.

504
00:32:06,930 --> 00:32:11,340
>> U issa, li jintroduċu inti
għal xi kmandi aktar.

505
00:32:11,340 --> 00:32:14,330
Avviż hawnhekk, li huwa qal we
kissru fil-linja 11, li hija

506
00:32:14,330 --> 00:32:16,230
printf, jidħol integer.

507
00:32:16,230 --> 00:32:21,260
Allura l-kmand jmiss se tkun kif
immorru l-linja li jmiss tal-kodiċi.

508
00:32:21,260 --> 00:32:24,810
Dan se jippermettilna naslu biex pass
permezz tal-linja programm tagħna b'linja.

509
00:32:24,810 --> 00:32:26,260
Allura li jmiss.

510
00:32:26,260 --> 00:32:29,820
>> Issa linja 12, aħna qed tmur
biex jiksbu l-eqreb numru sħiħ.

511
00:32:29,820 --> 00:32:30,450
Next.

512
00:32:30,450 --> 00:32:34,290
U jekk inti biss hit Ikteb darb'oħra, dan ser
jerġa 'jagħmel l-aħħar ħaġa li għamilt.

513
00:32:34,290 --> 00:32:36,480
So I m'għandhomx bżonn li tip
jmiss kull darba.

514
00:32:36,480 --> 00:32:40,100
Allura jidħol integer, 13.

515
00:32:40,100 --> 00:32:46,940
Allura issa, linja 14, filwaqt i huwa akbar
minn 10, u jien ser tagħmel li jmiss.

516
00:32:46,940 --> 00:32:48,685
U naraw aħna qed tmur biex decrement i.

517
00:32:48,685 --> 00:32:50,210
Allura aħna qed tmur biex decrement i ġdid.

518
00:32:50,210 --> 00:32:53,620
>> Allura issa, ieħor utli
kmand Stampa.

519
00:32:53,620 --> 00:32:55,750
Allura Stampa se jistampa
il-valur tal-varjabbli.

520
00:32:55,750 --> 00:32:57,825
Ejja jġibu l-valur
ta 'varjabbli i.

521
00:32:57,825 --> 00:32:58,705
Ejja jistampaw i.

522
00:32:58,705 --> 00:33:00,910
Huwa ser ngħid i huwa 11.

523
00:33:00,910 --> 00:33:03,330
Issa aħna jmiss darb'oħra filwaqt li
i huwa akbar minn 10.

524
00:33:03,330 --> 00:33:05,590
Hekk i għadu akbar minn
10, peress li huwa 11.

525
00:33:05,590 --> 00:33:06,920
i minus minus.

526
00:33:06,920 --> 00:33:08,250
Ejja jistampaw i ġdid.

527
00:33:08,250 --> 00:33:10,950
Kif kien mistenni, huwa 10.

528
00:33:10,950 --> 00:33:12,510
>> Allura issa, li jmiss.

529
00:33:12,510 --> 00:33:16,250
Huwa sejjer lura l-kundizzjoni, i huwa
akbar minn 10, iżda i issa huwa 10, hekk

530
00:33:16,250 --> 00:33:20,040
mhuwiex aktar minn 10, hekk aħna nistennew
li jaqgħu barra mill-linja waqt.

531
00:33:20,040 --> 00:33:22,220
U issa aħna qed hawn taħt dik il-linja tal-kodiċi.

532
00:33:22,220 --> 00:33:28,750
U l-iggwidar, ieħor Lista, huwa biss se
li juri l-preċedenti u li jmiss

533
00:33:28,750 --> 00:33:31,240
koppja ta 'linji ta' kodiċi, b'mod
każ li inti mitlufa yourself.

534
00:33:31,240 --> 00:33:35,420
Allura aħna biss ħareġ dan loop filwaqt li,
u issa dħalna dan

535
00:33:35,420 --> 00:33:37,080
filwaqt li loop, linja 18.

536
00:33:37,080 --> 00:33:39,860
Għalhekk, filwaqt li i ma tkunx daqs 0.

537
00:33:39,860 --> 00:33:46,570
U, li jmiss, i huwa ugwali i minus 3, u aħna ser
avviż, dan ser biss iżommu għaddejjin.

538
00:33:46,570 --> 00:33:48,270
U nistgħu jistampaw i.

539
00:33:48,270 --> 00:33:49,990
>> Kull kmand tip ta ikollu shortcuts.

540
00:33:49,990 --> 00:33:51,720
Allura p huwa qasir għall Stampa.

541
00:33:51,720 --> 00:33:53,400
Allura nistgħu i p.

542
00:33:53,400 --> 00:33:57,550
Just iżommu azjenda n,
jew iżommu tagħmel jmiss.

543
00:33:57,550 --> 00:33:58,340
Stampa i darb'oħra.

544
00:33:58,340 --> 00:34:00,380
You see issa huwa negattiv 167.

545
00:34:00,380 --> 00:34:06,030
Allura dan se jmorru fuq għal dejjem, iżda mhux
verament dejjem, peress li inti biss raw, huwa

546
00:34:06,030 --> 00:34:09,330
fil-fatt se jispiċċaw f'xi punt.

547
00:34:09,330 --> 00:34:15,699
>> Allura li hija Mibdi GDB.

548
00:34:15,699 --> 00:34:19,504
Imma ejja nagħmlu ħaġ'oħra fil GDB.

549
00:34:19,504 --> 00:34:20,754
Uh, debug.

550
00:34:20,754 --> 00:34:23,540

551
00:34:23,540 --> 00:34:28,534
Għalhekk, f'dan il-każ partikolari, il-
loop infinita ġara li jkun ġewwa ta '

552
00:34:28,534 --> 00:34:30,050
il-funzjoni prinċipali.

553
00:34:30,050 --> 00:34:35,779
U għal issa, biss taċċetta li din jien
ser jiċċaqalqu l loop infinita fis

554
00:34:35,779 --> 00:34:37,029
il-funzjoni foo.

555
00:34:37,029 --> 00:34:40,679

556
00:34:40,679 --> 00:34:43,730
Just ftakar li, fit-tmiem ta 'dan
programm, ukoll, dan kien oriġinarjament

557
00:34:43,730 --> 00:34:46,210
ssejjaħ foo, li kien biss
morna għall-istampa i.

558
00:34:46,210 --> 00:34:51,880
Iżda issa aħna qed ssejjaħ foo, li hija
se decrement i sakemm ikun 0, u

559
00:34:51,880 --> 00:34:54,548
imbagħad jistampaw dak il-varjabbli.

560
00:34:54,548 --> 00:34:55,469
OK.

561
00:34:55,469 --> 00:34:57,970
Ħlief dan.

562
00:34:57,970 --> 00:35:00,175
Għamla debug.

563
00:35:00,175 --> 00:35:03,310
U issa, debug GDB.

564
00:35:03,310 --> 00:35:04,090
OK.

565
00:35:04,090 --> 00:35:10,580
>> Mela jekk jien biss Mexxi allura jien mhux ser
jkunu jistgħu attwalment pass permezz tiegħi

566
00:35:10,580 --> 00:35:11,730
program-line mill-linja.

567
00:35:11,730 --> 00:35:19,820
Mela ejja break fil prinċipali,
u mbagħad it-tip run.

568
00:35:19,820 --> 00:35:28,160
Allura jmorru permezz ta 'dan, printf, jidħol
integer, jiksbu l-eqreb numru sħiħ, 13.

569
00:35:28,160 --> 00:35:34,180

570
00:35:34,180 --> 00:35:37,490
Allura aħna qed tmur biex iżommu decrementing
sakemm i huwa akbar minn 10.

571
00:35:37,490 --> 00:35:42,840
Imbagħad aħna qed tmur biex jaqgħu permezz tal-
filwaqt li loop, u biex tikseb l-linja -

572
00:35:42,840 --> 00:35:44,364
ejja tiftaħ it up fil-tieqa separata.

573
00:35:44,364 --> 00:35:48,720

574
00:35:48,720 --> 00:35:53,300
Allura aħna decremented sakemm i ma kienx għadu
akbar minn 10, u allura aħna

575
00:35:53,300 --> 00:35:55,700
imsejjaħ il-funzjoni, foo.

576
00:35:55,700 --> 00:36:01,340
>> Allura dak li ġara hekk kif I hit
foo funzjoni, ukoll, I imsejħa foo, u

577
00:36:01,340 --> 00:36:04,030
imbagħad I ma kellhomx kontroll fuq GDB.

578
00:36:04,030 --> 00:36:10,230
Allura malli I hit jmiss fil-linja,
affarijiet jitkomplew sakemm dan ġara,

579
00:36:10,230 --> 00:36:12,400
fejn il-programm ħareġ meta -

580
00:36:12,400 --> 00:36:14,450
jassumu ma kinux jeżistu eventwalment.

581
00:36:14,450 --> 00:36:16,390
Inti raw dan nieqaf għal ftit għalkemm.

582
00:36:16,390 --> 00:36:22,040
Allura għaliex ma I titlef kontroll fuq
il-programm f'dak il-punt?

583
00:36:22,040 --> 00:36:27,540
Well, meta I tip li jmiss, li tmur lil
il-linja litterali jmiss ta 'kodiċi li

584
00:36:27,540 --> 00:36:28,850
se tesegwixxi.

585
00:36:28,850 --> 00:36:35,950
Allura wara linja 21, il-linja li jmiss tal-kodiċi
li għandha tesegwixxi hija linja 22,

586
00:36:35,950 --> 00:36:38,520
li huwa, joħorġu mill-mejn.

587
00:36:38,520 --> 00:36:43,810
So I ma jridux biss jmorru
mal-linja li jmiss ta 'kodiċi.

588
00:36:43,810 --> 00:36:48,170
Irrid li jmorru fil-funzjoni, foo,
u imbagħad pass wkoll permezz

589
00:36:48,170 --> 00:36:49,830
dawk il-linji ta 'kodiċi.

590
00:36:49,830 --> 00:36:53,726
>> Allura għal dan, għandna alternattiva.

591
00:36:53,726 --> 00:36:56,770
Ejja nieqaf li għal darb'oħra.

592
00:36:56,770 --> 00:36:58,020
Break prinċipali.

593
00:36:58,020 --> 00:37:00,520

594
00:37:00,520 --> 00:37:06,370
Uh, 1, li jmiss, li jmiss, 13, jmiss,
jmiss, li jmiss, b'attenzjoni,

595
00:37:06,370 --> 00:37:09,820
qabel we hit linja foo.

596
00:37:09,820 --> 00:37:10,520
OK.

597
00:37:10,520 --> 00:37:13,700
>> Allura issa, aħna qed fil-linja 21,
fejn nitolbu foo.

598
00:37:13,700 --> 00:37:17,100
Aħna ma rridux li tip li jmiss, peress li
se biss sejħa l-foo funzjoni, u

599
00:37:17,100 --> 00:37:18,710
mur l-linja li jmiss tal-kodiċi.

600
00:37:18,710 --> 00:37:20,840
Dak li trid tuża hija Pass.

601
00:37:20,840 --> 00:37:25,690
Allura hemm differenza bejn Step
u Sussegwentement, fejn Pass passi fil-

602
00:37:25,690 --> 00:37:28,190
jiffunzjonaw, u Next tmur
fuq il-funzjoni.

603
00:37:28,190 --> 00:37:32,830
Hija biss tesegwixxi l-intier ta '
l-funzjoni u jżomm għaddejjin.

604
00:37:32,830 --> 00:37:37,210
>> Allura Pass se jressaqna
fil-funzjoni, foo.

605
00:37:37,210 --> 00:37:41,160
U naraw hawn, issa, aħna qed lura fuq
dan loop filwaqt li l-, fit-teorija,

606
00:37:41,160 --> 00:37:44,190
se tkompli dejjem.

607
00:37:44,190 --> 00:37:50,420
U jekk inti hit Pass, meta lanqas hija
funzjoni li jsejħu, allura huwa

608
00:37:50,420 --> 00:37:51,720
identika għal Next.

609
00:37:51,720 --> 00:37:55,320
Allura huwa biss meta int fuq linja li
hija ssejjaħ funzjoni li Jiżdiedu

610
00:37:55,320 --> 00:37:56,970
se jvarjaw minn Next.

611
00:37:56,970 --> 00:37:57,930
Allura Step se jressaqna hawn.

612
00:37:57,930 --> 00:38:02,100
Pass, pass, pass, pass, pass, pass, u
Aħna ser biss loop infinita dejjem.

613
00:38:02,100 --> 00:38:06,810
>> Allura inti tista 'tikseb użati biex li bħala tiegħek
mod ta 'identifikazzjoni loops infinita, hija

614
00:38:06,810 --> 00:38:08,960
biss li żżomm din il Enter biex
tara fejn ikollok staġnati.

615
00:38:08,960 --> 00:38:11,610

616
00:38:11,610 --> 00:38:14,780
Hemm modi aħjar biex tagħmel dan, iżda
għal issa, li huwa perfettament suffiċjenti.

617
00:38:14,780 --> 00:38:17,967
U stylistically, li jikkonformaw mad Style
50, I għandu għamlu dan.

618
00:38:17,967 --> 00:38:21,550

619
00:38:21,550 --> 00:38:24,030
OK.

620
00:38:24,030 --> 00:38:28,400
>> Allura aħħar kmand wieħed li tintroduċi.

621
00:38:28,400 --> 00:38:30,810
Well, ejja GDB debug pulzieri

622
00:38:30,810 --> 00:38:35,580
Allura minflok tkissir fi prinċipali, jekk I
jafu l-funzjoni foo huwa wkoll il-

623
00:38:35,580 --> 00:38:39,230
problema, imbagħad I jista 'jkollhom biss
qal, break fil foo, minflok.

624
00:38:39,230 --> 00:38:42,310
Ejja ngħidu I break fi
kemm prinċipali u foo.

625
00:38:42,310 --> 00:38:45,390
Allura inti tista 'tistabbilixxi kif ħafna breakpoints
kif tixtieq.

626
00:38:45,390 --> 00:38:49,230
Meta tip I run, li għaddej
biex tieqaf fil--

627
00:38:49,230 --> 00:38:52,180
ooh, ejja recompile, peress
I mibdula affarijiet.

628
00:38:52,180 --> 00:38:55,950
Int ser ikollok tara din il-linja, Twissija, sors
fajl huwa aktar riċenti minn eżekutibbli.

629
00:38:55,950 --> 00:38:59,680
Allura dan ifisser li jien biss marru fil hawn
u mibdula dawn biex jikkonformaw ma 'Style

630
00:38:59,680 --> 00:39:03,100
50, imma jien ma recompile
il-programm.

631
00:39:03,100 --> 00:39:04,870
So GDB jagħmel me konxji ta 'dak.

632
00:39:04,870 --> 00:39:10,130
I ser nieqaf, jagħmlu debug darb'oħra,
hit debug GDB.

633
00:39:10,130 --> 00:39:10,700
OK.

634
00:39:10,700 --> 00:39:12,800
>> Allura issa, lura għal dak li kien isir.

635
00:39:12,800 --> 00:39:15,720
Break prinċipali, break foo.

636
00:39:15,720 --> 00:39:20,680
Issa jekk I run-programm, dan huwa
se tkompli sakemm hits

637
00:39:20,680 --> 00:39:21,320
breakpoint.

638
00:39:21,320 --> 00:39:24,680
Li breakpoint jiġri li
tkun l-ewwel waħda fl prinċipali.

639
00:39:24,680 --> 00:39:28,630
Issa, minflok tagħmel li jmiss, li jmiss, li jmiss,
jmiss, li jmiss, sal I hit foo, I

640
00:39:28,630 --> 00:39:35,230
tista tip tkompli, li se jkompli
sakemm inti hit l-breakpoint jmiss.

641
00:39:35,230 --> 00:39:37,200
I jkollhom jidħlu n-numru sħiħ l-ewwel.

642
00:39:37,200 --> 00:39:40,570
Kompli se tkompli sakemm I hit l-
breakpoint li jmiss, li huwa li

643
00:39:40,570 --> 00:39:43,320
funzjoni ta 'foo.

644
00:39:43,320 --> 00:39:50,130
>> Allura Run se jimxu sakemm inti hit
breakpoint, iżda inti biss tip run meta

645
00:39:50,130 --> 00:39:54,060
int tibda l-programm, u mbagħad,
Minn hemm, huwa jkompli.

646
00:39:54,060 --> 00:40:01,950
Jekk I biss ma break prinċipali u
imbagħad dam, dan ser jinkiser fi

647
00:40:01,950 --> 00:40:03,670
prinċipali, u mbagħad kompli.

648
00:40:03,670 --> 00:40:10,050
Peress li jien ma jkollhom punt tal-qasma fil foo,
jidħlu fil-numru sħiħ, allura issa jien

649
00:40:10,050 --> 00:40:11,380
mhux se break fil-foo.

650
00:40:11,380 --> 00:40:16,318
Huwa biss se infinita
loop sakemm dik.

651
00:40:16,318 --> 00:40:17,568
OK.

652
00:40:17,568 --> 00:40:19,500

653
00:40:19,500 --> 00:40:24,420
>> Allura dak Intro li GDB.

654
00:40:24,420 --> 00:40:27,790
Għandek tibda tuża din
f'settijiet problematiċi tiegħek.

655
00:40:27,790 --> 00:40:30,550
Hija tista 'tkun ferm utli
biex jidentifikaw bugs.

656
00:40:30,550 --> 00:40:35,280
Jekk inti fil-fatt biss, linja b'linja minn, jmorru
permezz kodiċi tiegħek, u jqabblu dak li huwa

657
00:40:35,280 --> 00:40:39,740
verament jiġri ma 'dak li inti tistenna
li jiġri, allura huwa pjuttost

658
00:40:39,740 --> 00:40:41,060
diffiċli li jitilfu bugs tiegħek.

659
00:40:41,060 --> 00:40:45,280

660
00:40:45,280 --> 00:40:46,530
OK.

661
00:40:46,530 --> 00:40:48,310

662
00:40:48,310 --> 00:40:54,040
>> Allura aħħar ġimgħa David aġġornati dan
Jittieħed kriptografija sigriet ewlieni għall-

663
00:40:54,040 --> 00:40:59,350
ewwel darba, fejn ma rridux
passwords biss jiġu maħżuna fuq tagħna

664
00:40:59,350 --> 00:41:03,210
kompjuter f'xi fajl test sempliċi, fejn
xi ħadd jista 'jiġi maż u biss

665
00:41:03,210 --> 00:41:04,660
jiftħuh u jaqrahom.

666
00:41:04,660 --> 00:41:07,530
Idealment, huma jkunu encrypted
b'xi mod.

667
00:41:07,530 --> 00:41:13,340
U fil Problem Set 2, inti ser tkun jittrattaw
ma 'metodu wieħed ta' encryption,

668
00:41:13,340 --> 00:41:16,520
jew, ukoll, żewġ metodi, iżda
mhumiex daqshekk kbira.

669
00:41:16,520 --> 00:41:20,050
Jekk inti tagħmel l-Hacker edizzjoni, int
wkoll se jkunu jittrattaw

670
00:41:20,050 --> 00:41:22,150
decrypting xi affarijiet.

671
00:41:22,150 --> 00:41:29,770
>> Allura l-kwistjoni issa hija, ukoll, anke jekk
aħna għandna l-encryption aktar b'saħħithom

672
00:41:29,770 --> 00:41:34,830
algoritmu fid-dinja, jekk inti tagħżel
password partikolarment dgħajfa, allura

673
00:41:34,830 --> 00:41:37,720
mhux se jgħinek ħafna, billi n-nies
xorta se tkun tista 'figura hija out.

674
00:41:37,720 --> 00:41:41,530
Anki jekk tara l-sekwenza encrypted u
jidher qisu mess ta 'żibel

675
00:41:41,530 --> 00:41:44,760
dan ifisser xejn għalihom, jekk dawn
xorta biss bżonn biex tipprova ftit passwords

676
00:41:44,760 --> 00:41:50,560
figura hija out, allura inti
mhumiex sikura ħafna.

677
00:41:50,560 --> 00:41:55,890
Allura jaraw a video li
jagħmel il-punt.

678
00:41:55,890 --> 00:41:59,587

679
00:41:59,587 --> 00:42:00,970
>> [VIDEO Daqq]

680
00:42:00,970 --> 00:42:02,100
>> -Elmu, inti fiend.

681
00:42:02,100 --> 00:42:03,370
X'qed jiġri?

682
00:42:03,370 --> 00:42:05,170
X'Ser tagħmel biex bint tiegħi?

683
00:42:05,170 --> 00:42:09,910
>> -Permess me jintroduċu l-brillanti
kirurgu tal-plastik żgħażagħ, Dr Phillip

684
00:42:09,910 --> 00:42:13,730
Schlotkin, l-akbar imnieħer
bniedem impjiegi fil-kollu

685
00:42:13,730 --> 00:42:16,080
univers, u Beverly Hills.

686
00:42:16,080 --> 00:42:17,210
>> -Your Altezza.

687
00:42:17,210 --> 00:42:18,070
>> -Imnieħer impjieg?

688
00:42:18,070 --> 00:42:18,670
Ma nifhimx.

689
00:42:18,670 --> 00:42:20,090
Hi diġà kellha impjieg imnieħer.

690
00:42:20,090 --> 00:42:21,910
Kienet ħelu sittax preżenti.

691
00:42:21,910 --> 00:42:22,140
>> No.

692
00:42:22,140 --> 00:42:23,690
Mhuwiex X'taħseb.

693
00:42:23,690 --> 00:42:25,420
Huwa ħafna, ħafna agħar.

694
00:42:25,420 --> 00:42:30,300
Jekk inti ma jagħtux me-kombinazzjoni li
l-ilqugħ arja, Dr Schlotkin se

695
00:42:30,300 --> 00:42:34,226
tagħti tifla tiegħek lura imnieħer tagħha qodma.

696
00:42:34,226 --> 00:42:35,476
>> No.

697
00:42:35,476 --> 00:42:38,712

698
00:42:38,712 --> 00:42:40,516
Fejn ma ikollok dan?

699
00:42:40,516 --> 00:42:41,440
>> -Id-dritt.

700
00:42:41,440 --> 00:42:42,180
I ser jgħidlek.

701
00:42:42,180 --> 00:42:43,381
I ser jgħidlek.

702
00:42:43,381 --> 00:42:44,263
Le, daddy.

703
00:42:44,263 --> 00:42:45,590
Le, inti ma trid.

704
00:42:45,590 --> 00:42:46,860
>> -You're dritt, għeżież tiegħi.

705
00:42:46,860 --> 00:42:48,450
I ser titlef imnieħer ġdida tiegħek.

706
00:42:48,450 --> 00:42:52,090
Imma jien mhux se tgħidlu-kombinazzjoni,
x'ikun.

707
00:42:52,090 --> 00:42:53,680
>> -Tajjeb ħafna.

708
00:42:53,680 --> 00:42:55,685
Dr Schlotkin, jagħmlu agħar tiegħek.

709
00:42:55,685 --> 00:42:56,914
>> My divertiment.

710
00:42:56,914 --> 00:43:00,690
>> [Għodda li tkun qiegħda inċiżiv]

711
00:43:00,690 --> 00:43:01,910
>> No.

712
00:43:01,910 --> 00:43:02,520
Stenna.

713
00:43:02,520 --> 00:43:03,836
Stenna.

714
00:43:03,836 --> 00:43:05,300
I ser jgħidlek.

715
00:43:05,300 --> 00:43:06,880
I ser jgħidlek.

716
00:43:06,880 --> 00:43:09,130
>> -I kien jaf ikun xogħol.

717
00:43:09,130 --> 00:43:09,900
Kull dritt.

718
00:43:09,900 --> 00:43:12,850
Agħti lili.

719
00:43:12,850 --> 00:43:16,918
>> -Il-kombinazzjoni hija waħda.

720
00:43:16,918 --> 00:43:17,406
>> -One.

721
00:43:17,406 --> 00:43:18,382
>> -One.

722
00:43:18,382 --> 00:43:19,358
>> -Tnejn.

723
00:43:19,358 --> 00:43:19,846
>> -Tnejn.

724
00:43:19,846 --> 00:43:20,822
>> -Tnejn.

725
00:43:20,822 --> 00:43:21,310
>> -Tliet.

726
00:43:21,310 --> 00:43:21,798
>> -Tliet.

727
00:43:21,798 --> 00:43:22,774
>> -Tliet.

728
00:43:22,774 --> 00:43:23,262
>> -Erba.

729
00:43:23,262 --> 00:43:23,750
>> -Erba.

730
00:43:23,750 --> 00:43:26,150
>> -Erba.

731
00:43:26,150 --> 00:43:27,010
>> Five.

732
00:43:27,010 --> 00:43:27,670
>> Five.

733
00:43:27,670 --> 00:43:29,010
>> Five.

734
00:43:29,010 --> 00:43:34,770
>> -Allura l-kombinazzjoni tkun waħda,
tnejn, tlieta, erba ', ħames.

735
00:43:34,770 --> 00:43:37,460
Dik hija l-kombinazzjoni stupidest
I qatt semgħu fil-ħajja tiegħi.

736
00:43:37,460 --> 00:43:39,710
Dik hija l-tip ta 'ħaġa idjota
jkollha fuq bagalji tiegħu.

737
00:43:39,710 --> 00:43:42,000
>> -Grazzi, Altezza tiegħek.

738
00:43:42,000 --> 00:43:43,530
>> -X'għamilt?

739
00:43:43,530 --> 00:43:44,490
>> -I daru off-ħajt.

740
00:43:44,490 --> 00:43:45,420
>> No inti ma.

741
00:43:45,420 --> 00:43:45,840
You mitfija l-film kollu.

742
00:43:45,840 --> 00:43:46,930
>> -I irid ikun ippressat-buttuna ħażin.

743
00:43:46,930 --> 00:43:48,265
>> Well, erġa 'poġġih fuq.

744
00:43:48,265 --> 00:43:49,110
Poġġi l-movie lura fuq.

745
00:43:49,110 --> 00:43:49,510
>> -Iva, sir.

746
00:43:49,510 --> 00:43:49,917
Iva, sir.

747
00:43:49,917 --> 00:43:50,324
>> -Ejja ħa mmorru, Arnold.

748
00:43:50,324 --> 00:43:51,140
Come, Gretchen.

749
00:43:51,140 --> 00:43:53,060
Of course, inti taf I taf xorta
jkollhom inti kont għal dan.

750
00:43:53,060 --> 00:43:53,440
>> [Video daqq END]

751
00:43:53,440 --> 00:43:54,690
>> ROB BODEN: Kull dritt.

752
00:43:54,690 --> 00:43:59,690

753
00:43:59,690 --> 00:44:08,430
Allura issa li aħna diġà qed jitkellem dwar
sigurtà f'ċerti modi, sbieħ

754
00:44:08,430 --> 00:44:16,050
ftit poster movie, hekk fl-aħħar
jiem, dawn il-kwistjonijiet mal-NSA

755
00:44:16,050 --> 00:44:17,300
monitoraġġ kollox.

756
00:44:17,300 --> 00:44:21,840

757
00:44:21,840 --> 00:44:26,930
Jista 'jkun diffiċli li jħossu bħal inti
jkollhom xi tip ta 'privatezza fis-

758
00:44:26,930 --> 00:44:34,540
dinja online, għalkemm I ma setax jgħid
inti ħafna mill-dettalji ta 'priżma.

759
00:44:34,540 --> 00:44:42,130
Allura superazzjoni PRISM, aħna qed mhux se
li jkun jitkellem dwar dan, issa

760
00:44:42,130 --> 00:44:44,030
jaħsbu dwar laptop tiegħek.

761
00:44:44,030 --> 00:44:48,360
Allura up hawn, nixtieq li jaqilbu
kont attwali tiegħi,

762
00:44:48,360 --> 00:44:50,370
bil pingwin ftit tiegħi.

763
00:44:50,370 --> 00:44:57,310
So I ikollhom sett password, u li
password huwa kwalunkwe I tixtieq li jkun.

764
00:44:57,310 --> 00:45:02,430
>> Imma ftakar li dak li jien qtugħ
ma ', għalhekk dan login

765
00:45:02,430 --> 00:45:04,850
pront, hija xi program.

766
00:45:04,850 --> 00:45:07,910
Huwa xi programm li kien
miktub minn xi persuna.

767
00:45:07,910 --> 00:45:13,250
U għalhekk, dik il-persuna, jekk huma
partikolarment malizzjużi, dawn jistgħu

768
00:45:13,250 --> 00:45:17,780
qalu, id-dritt, hekk jekk l-password
I jidħlu hija ugwali għal tiegħi

769
00:45:17,780 --> 00:45:22,800
password attwali, jew huwa ugwali
għal xi password speċjali -

770
00:45:22,800 --> 00:45:25,550
David huwa tal-biża jew xi ħaġa -

771
00:45:25,550 --> 00:45:27,190
imbagħad ħallihom pulzieri

772
00:45:27,190 --> 00:45:33,760
Allura programmer malizzjuż jista 'jkollu
aċċess għall kollha tal MACs tiegħek, jew

773
00:45:33,760 --> 00:45:36,150
Windows, jew xejn.

774
00:45:36,150 --> 00:45:41,980
>> Allura li mhuwiex ħafna ta 'tħassib, peress li,
I mean, dan huwa program login

775
00:45:41,980 --> 00:45:48,720
li konsenjat bil OS X, mijiet
jew eluf ta 'nies ikollhom

776
00:45:48,720 --> 00:45:50,020
rivedut dan il-kodiċi.

777
00:45:50,020 --> 00:45:55,330
U hekk, jekk, fil-kodiċi tiegħek x'imkien, inti
jgħidu jekk dan string ugwali ugwali

778
00:45:55,330 --> 00:45:58,860
David huwa tal-biża, login, allura xi ħadd huwa
se jkun, bħal, stenna.

779
00:45:58,860 --> 00:45:59,800
Dan mhuwiex dritt.

780
00:45:59,800 --> 00:46:01,790
Dan m'għandux ikun hawnhekk.

781
00:46:01,790 --> 00:46:06,650
Allura dak mod wieħed nikbru affarijiet
li jkun it-tip ta 'sigur.

782
00:46:06,650 --> 00:46:10,300
>> Imma naħseb dwar anki programmi
li tikteb.

783
00:46:10,300 --> 00:46:13,000
Ejja ngħidu li inti kiteb il-programm login.

784
00:46:13,000 --> 00:46:20,440
Allura dan il-programm login li inti kiteb,
hekk ovvjament, inti tajba

785
00:46:20,440 --> 00:46:21,210
programmer.

786
00:46:21,210 --> 00:46:25,610
Int mhux se jagħmlu l-ebda malizzjużi
jekk x ugwali ugwali David huwa tal-biża

787
00:46:25,610 --> 00:46:27,860
fil-kodiċi tiegħek.

788
00:46:27,860 --> 00:46:31,930
Iżda dan il-programm, liema do you
jużaw biex jikkompilaw dan il-programm?

789
00:46:31,930 --> 00:46:34,180
Xi ħaġa simili Clang.

790
00:46:34,180 --> 00:46:38,460
Allura dak li jekk il-persuna li ġara
jiktbu Clang speċjali b'għata fil Clang

791
00:46:38,460 --> 00:46:44,310
xi ħaġa simili, jekk jiena kompilazzjoni tal-
login programm, allura jidħol dan il-kodiċi

792
00:46:44,310 --> 00:46:49,720
fil-programm login li tgħid, jekk
x ugwali ugwali David huwa tal-biża?

793
00:46:49,720 --> 00:46:59,890
Allura ma pjuttost s'issa, iżda aħna għandna l-istess
toħroġ hawn, fejn Clang, ukoll,

794
00:46:59,890 --> 00:47:03,790
eluf, jekk mhux għexieren ta 'eluf ta'
nies, ħarsu lejn Clang, għandhom

795
00:47:03,790 --> 00:47:07,160
ħares lejn linji tiegħu ta 'kodiċi u qal,
id-dritt, hemm xejn ħażin hawn.

796
00:47:07,160 --> 00:47:10,680
Ovvjament, l-ebda waħda qed tagħmel
xejn dan malizzjużi.

797
00:47:10,680 --> 00:47:15,780
>> Imma dak li hu Clang innifsu, bħal,
jekk dak I jikkompilaw Clang?

798
00:47:15,780 --> 00:47:20,900
X'jiġri jekk I għandhom xi kompilatur li
jikkompila Clang li introduċa fid Clang

799
00:47:20,900 --> 00:47:25,610
dan Hack speċjali li jgħid, id-dritt,
meta I jikkompilaw Clang, allura l-

800
00:47:25,610 --> 00:47:31,290
eżekutibbli niġi għandu apposta tfittex
ġewwa tal-programm login u daħħal

801
00:47:31,290 --> 00:47:34,230
dan password, ugwali ugwali
Dave huwa tal-biża?

802
00:47:34,230 --> 00:47:37,990
Mela ftakar li kompilatur tiegħek innifsu
jeħtieġ li jiġi kkompilat f'xi punt.

803
00:47:37,990 --> 00:47:42,810
Hekk jekk dak li inti tagħżel li tiġbor Clang
ma ', fih innifsu huwa malizzjużi, allura inti

804
00:47:42,810 --> 00:47:45,580
jistgħu jiġu invitat kollox
mod il-linja.

805
00:47:45,580 --> 00:47:49,630
>> Allura hawnhekk, għandna Ken Thompson
u Dennis Ritchie.

806
00:47:49,630 --> 00:47:53,780
Allura dan huwa ritratt emblematika.

807
00:47:53,780 --> 00:47:55,470
Dennis Ritchie huwa fuq il-lemin.

808
00:47:55,470 --> 00:47:58,740
Huwa importanti -

809
00:47:58,740 --> 00:48:03,640
pretty ħafna kiteb C. Allura inti tista '
nirringrazzja lilu għal din il-klassi.

810
00:48:03,640 --> 00:48:04,840
Ken Thomson fuq ix-xellug.

811
00:48:04,840 --> 00:48:07,780
L-tnejn minnhom bażikament kiteb UNIX.

812
00:48:07,780 --> 00:48:10,140
Ukoll, dawn kienu kontributuri ewlenin
fil UNIX.

813
00:48:10,140 --> 00:48:11,310
Kien hemm xi oħrajn.

814
00:48:11,310 --> 00:48:16,240
Allura Ken Thompson, f'xi punt,
jirbaħ il-Premju Turing.

815
00:48:16,240 --> 00:48:20,860
U l-għoti Turing, stajt dejjem jinstemgħu
it referenza B'dan il-mod, huwa l-

816
00:48:20,860 --> 00:48:23,100
Premju Nobel tax-xjenza tal-kompjuter.

817
00:48:23,100 --> 00:48:27,500
>> Allura fil-Premju Turing, huwa għandu
jagħti diskors aċċettazzjoni tiegħu.

818
00:48:27,500 --> 00:48:31,790
U huwa jagħti dan id-diskors famużi ħafna
issa, imsejħa Riflessjonijiet dwar Fidu

819
00:48:31,790 --> 00:48:35,620
Trust, li aħna marbutin
'biex fuq il-websajt kors.

820
00:48:35,620 --> 00:48:41,670
U f'dan diskors, huwa jgħid, id-dritt,
so I kiteb UNIX, u issa kollha

821
00:48:41,670 --> 00:48:43,320
inti nies qed jużaw UNIX.

822
00:48:43,320 --> 00:48:46,960
Issa, ftakar llum li Linux huwa
dixxendent dirett ta 'UNIX.

823
00:48:46,960 --> 00:48:50,140
OS X juża direttament UNIX.

824
00:48:50,140 --> 00:48:53,810
Windows ma tant, iżda ħafna
ta 'ideat kienu meħuda mill UNIX.

825
00:48:53,810 --> 00:48:59,220
>> Hekk hu tmur sa l-istadju u jgħid,
id-dritt, I kiteb UNIX.

826
00:48:59,220 --> 00:49:03,940
U biss sabiex inti guys taf, jien
kapaċi log fis-kull

827
00:49:03,940 --> 00:49:05,590
wieħed biss ta 'kompjuters tiegħek.

828
00:49:05,590 --> 00:49:14,280
Peress I jitqiegħdu waħda minn dawn speċjali jekk x
ugwali ugwali Ken Thomson huwa tal-biża,

829
00:49:14,280 --> 00:49:16,350
allura jien permessi li login.

830
00:49:16,350 --> 00:49:18,370
Sabiex in-nies huma simili, ukoll,
how'd inti tagħmel dan?

831
00:49:18,370 --> 00:49:21,090
Ħarisna lejn il-programm login
u xejn hemm.

832
00:49:21,090 --> 00:49:24,700
He simili, ukoll, I modifikata l-kumpilatur
log fil-programm login

833
00:49:24,700 --> 00:49:30,490
sabiex il-programm login issa se jkollhom
li x ugwali ugwali Ken Thompson

834
00:49:30,490 --> 00:49:31,700
huwa tal-biża.

835
00:49:31,700 --> 00:49:33,120
>> U jgħidu, ukoll, li mhux veru.

836
00:49:33,120 --> 00:49:35,740
Aħna qed tħares lejn il-kompilatur, u l-
kompilatur ma jkollhom l-ebda linji ta '

837
00:49:35,740 --> 00:49:36,400
kodiċi bħal dik.

838
00:49:36,400 --> 00:49:40,540
He simili, OK, imma dak li huma inti
kompilazzjoni tal-kompilatur ma?

839
00:49:40,540 --> 00:49:44,810
U jaħsbu, u hu, bħal, ukoll,
Jien il-wieħed li ħadt l-kumpilatur

840
00:49:44,810 --> 00:49:50,580
inti qed tuża biex jikkompilaw l-kompilatur, hekk
inti kumpilazzjoni kompilatur, li

841
00:49:50,580 --> 00:49:56,390
nnifisha hija malizzjuż, u se
jiksru l-programm login.

842
00:49:56,390 --> 00:49:59,360
Allura bażikament, f'dak il-punt, hemm
ebda mod inti tista 'tħares lejn is-sors

843
00:49:59,360 --> 00:50:02,450
kodiċi tal-programm login
biex tara dak li hu ħażin.

844
00:50:02,450 --> 00:50:04,220
Inti ma tista 'saħansitra tfittex fil-
kodiċi sors tal-kompilatur

845
00:50:04,220 --> 00:50:06,790
biex tara dak li hu ħażin.

846
00:50:06,790 --> 00:50:11,940
>> Għandek bżonn biex tħares lejn il-magna
kodiċi, il-binarju attwali tal-

847
00:50:11,940 --> 00:50:16,760
kompilatur kkompilata biex tara, stenna, dawn
linji ta 'kodiċi m'għandux ikun hawn.

848
00:50:16,760 --> 00:50:22,130
Imma Ken Thompson ħa pass wieħed
ulterjuri u qal, ukoll, hemm

849
00:50:22,130 --> 00:50:25,980
dawn il-programmi speċjali li attwalment
tgħinek taqra l-binarju ta 'programmi,

850
00:50:25,980 --> 00:50:29,340
u hekk jekk xi ħadd użat dak il-programm għall-
aqra l-binarju, kienu jaraw dawn

851
00:50:29,340 --> 00:50:30,490
linji ta 'kodiċi.

852
00:50:30,490 --> 00:50:34,020
Huwa modifikati dawk il-programmi li jgħidu, kollha
dritt, jekk inti qed tfittex fil-

853
00:50:34,020 --> 00:50:38,460
kompilatur, ma jurux din partikolari
sett ta 'binarja.

854
00:50:38,460 --> 00:50:42,830
>> Mela allura għandek bżonn tieħu li pass
ulterjuri u bażikament, li jistgħu jkollhom

855
00:50:42,830 --> 00:50:46,210
livelli multipli meħuda ta 'indirection,
u f'xi punt, l-ebda wieħed fil-fatt

856
00:50:46,210 --> 00:50:47,990
ser jiġi verifikat.

857
00:50:47,990 --> 00:50:52,590
Allura l-morali ta 'l-istorja hija, int
mhux se jkun miktub

858
00:50:52,590 --> 00:50:54,340
Clang f'din il-klassi.

859
00:50:54,340 --> 00:50:57,020
Inti se tkun qed tuża tixbit
Clang ħafna f'din il-klassi.

860
00:50:57,020 --> 00:51:00,490
Għal kull taf, Clang huwa malizzjuż
programm li huwa sabotaging kull

861
00:51:00,490 --> 00:51:03,520
programm uniku inti stajt qatt ikkumpilata.

862
00:51:03,520 --> 00:51:08,206
U li tħallik fuq dik ominous ħafna
jinnota, ara inti nhar l-Erbgħa.

863
00:51:08,206 --> 00:51:10,030
>> [Applause]

864
00:51:10,030 --> 00:51:12,935
>> SPEAKER 2: Fl-CS50 jmiss.

865
00:51:12,935 --> 00:51:14,580
>> SPEAKER 3: M'għandekx inti DARE ngħid li.

866
00:51:14,580 --> 00:51:15,930
Tista 'tagħmel dan.

867
00:51:15,930 --> 00:51:19,440
Inti ghamilt dan qabel, inti tista 'tagħmel dan
illum, inti tista 'tagħmel dan għada.

868
00:51:19,440 --> 00:51:20,930
Inti kont qed tagħmel dan għal snin.

869
00:51:20,930 --> 00:51:22,790
Just go up hemm u jagħmlu dan.

870
00:51:22,790 --> 00:51:24,310
Tista 'tagħmel dan.

871
00:51:24,310 --> 00:51:26,102
>> [Daqq tal-mużika]