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>> [Daqq tal-mużika]

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>> [Daqq video]

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>> -He S tinsab.

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>> -Dwar xiex?

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>> -I Do not know.

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>> -Allura Dak li nafu?

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>> -Li Fil 09:15, Ray
Santoya kien fil-ATM.

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-Yeah.

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Għalhekk il-kwistjoni hija, dak
kien hu tagħmel fil 09:16?

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>> -Shooting-Millimetru 9 fuq xi ħaġa.

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Forsi hu ra l-sniper.

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>> -Jew kien jaħdem miegħu.

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>> -Wait.

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Mur lura wieħed.

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>> Liema tara?

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>> -Bring Wiċċu up full screen.

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>> Nuċċalijiet -His.

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>> -Hemm L riflessjoni.

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>> -Hija Hija l-tim tal-baseball Nuevitas.

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C'est logo tagħhom.

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>> -u Hu tkellem lil
min liebes dak ġakketta.

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>> [END Daqq]

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>> DAVID Malan: Kull dritt.

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Dan huwa CS50 u dan huwa daqsxejn aktar
ta [inaudible] li magħhom int

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dabbling bil-problema stabbiliti erba '.

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Illum tibda tfittex ftit aktar
profondament fil dawn l-affarijiet imsejħa pointers,

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li anki jekk huwa
suġġett pretty arcane,

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jirriżulta li huwa għaddej
jkun il-mezz li bih nistgħu

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tista 'tibda bini u l-assemblaġġ
programmi ħafna aktar sofistikati.

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Iżda aħna ma kien nhar l-Erbgħa l-aħħar
permezz ta 'xi claymation ewwel.

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Allura dan, irtirar, hija
Binky u aħna użati lilu

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li tagħti ħarsa lejn programm li
ma verament tagħmel xejn interessanti,

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iżda hija ma jikxfu xi ftit problemi.

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Allura biex tibda llum, għaliex ma we walk
malajr permezz ta 'ftit ta' dawn il-passi,

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jippruvaw jiddistillaw fi termini tal-bniedem
eżattament x'inhu għaddej hawn

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u għaliex dan huwa ħażin, u mbagħad jimxu fuq
u fil-fatt jibda jinbena xi ħaġa

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ma din it-teknika?

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Allura dawn kienu l-ewwel
żewġ linji f'dan il-programm

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u f'termini laymans, dak
huma dawn iż-żewġ linji tagħmel?

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Xi ħadd li raġonevolment komda
ma 'dak li ddikjarat fuq l-iskrin?

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Liema huma dawn iż-żewġ linji tagħmel?

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Huwa mhux kollha li
differenti minn ġimgħa,

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iżda jkun hemm xi simbolu speċjali ġdid.

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Yeah?

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Lura hemm.

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>> UDJENZA: Tiddikjara pointers?

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DAVID Malan: Say mill-ġdid?

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UDJENZA: Tiddikjara pointers?

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DAVID Malan: pointers tiddikjara u
ejja tirfina ftit aktar.

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UDJENZA: [inaudible]
indirizz x u mbagħad y.

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DAVID Malan: U mbagħad jindirizza.

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Allura speċifikament dak li aħna qed tagħmel
huwa aħna tiddikjara żewġ varjabbli.

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Dawn il-varjabbli, għalkemm, ser
li jkunu ta 'stilla int tip, li

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b'mod aktar speċifiku jfisser
huma ser taħżen

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l-indirizz ta 'int,
rispettivament, X u Y.

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Issa hemm xi valuri?

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Hemm xi indirizzi attwali f'dawn
żewġ varjabbli f'dan il-punt fil-ħin?

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No

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Huwa biss hekk imsejħa valuri taż-żibel.

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Jekk inti ma attwalment tassenja
varjabbli, ikun x'ikun kien fil RAM

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qabel se timla ma 'żerijiet
u dawk iż ta 'dawk varjabbli.

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Iżda aħna għadhom ma jafux
liema huma u dak l

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se jkun kruċjali għas għaliex Binky
mitlufa kap tiegħu aħħar ġimgħa.

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>> Għalhekk din kienet l claymation
Inkarnazzjoni ta 'dan

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fejn inti għandek biss żewġ varjabbli,
biċċiet ċirkolari ftit ta 'tafal,

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li jista 'jaħżen varjabbli, iżda bħala
l-vleġeġ jitgeżwer jissuġġerixxu,

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dawn mhux qed attwalment tipponta
biex kullimkien magħruf per se.

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Iva allura kellna din il-linja, u dan
kien aħħar ġimgħa ġdid, malloc għall-memorja

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allokazzjoni, li huwa biss mod fancy
javżak-sistema operattiva, Linux

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jew Mac OS jew Windows,
ħej, agħti lili xi memorja,

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u kull ma għandek tgħid
is-sistema operattiva

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huwa dak meta jitolbu dan għall-memorja.

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Huwa mhux se kura liema
int se tagħmel magħha,

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imma inti trid tghid l-funzjonament
sistema liema permezz ta 'malloc.

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Yeah?

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>> UDJENZA: Kemm?

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DAVID Malan: Kemm?

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Kemm fil bytes, u għalhekk, dan, għal darb'oħra,
eżempju artifiċjali, huwa biss qal,

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agħtini l-daqs ta 'int.

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Issa, id-daqs ta 'int
huwa erba bytes jew 32 bits.

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Allura dan huwa biss mod ta '
qal, ħej, sistema operattiva,

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tagħti me erba 'bytes ta' memorja
li nista 'nuża għad-dispożizzjoni tiegħi,

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u speċifikament, dak ma
ritorn malloc rigward

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għal dak blokki ta 'erba' bytes?

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UDJENZA: Indirizz?

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DAVID Malan: L-indirizz.

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L-indirizz ta 'dak blokki ta' erba 'bytes.

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Eżattament.

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U hekk dan huwa dak maħżun fl-aħħar
fil x u hu għalhekk li aħna ma verament

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kura dak in-numru ta 'dik
indirizz huwa, jekk huwa OX1 jew ox2

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jew xi indirizz hexadeċimali cryptic.

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Aħna biss kura pictorially
li dak il-varjabbli x issa huwa

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tipponta lejn dak blokki ta 'memorja.

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Allura l-vleġġa jirrappreżenta pointer, jew
b'mod aktar speċifiku, l-indirizz tal-memorja.

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Iżda għal darb'oħra, aħna ma tipikament kura
x'inhuma dawn l-indirizzi attwali huma.

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Issa, din il-linja jgħid
dak f'termini laymans?

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Star x gets 42 virgola.

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Xi jfisser dan?

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Inti tixtieq tmur?

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Ma scratch għonq tiegħek.

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>> UDJENZA: L-indirizz ta 'x hija fil-42.

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>> DAVID Malan: L-indirizz ta 'x huwa fil 42.

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Mhux pjuttost.

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Allura qrib, iżda pjuttost mhux, għaliex hemm
l-istilla li l-prefiss dan x.

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Għalhekk għandna bżonn li tweak ftit.

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Yeah?

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>> UDJENZA: Il-valur li l-
pointer x hija li tipponta lejn huwa 42.

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DAVID Malan: OK.

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Il-valur li l-pointer x hija
tipponta lejn, ejja ngħidu, għandhom ikunu 42,

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jew imqiegħda mod ieħor, l-istilla
x jgħid, mur għal dak kollu indirizz

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huwa x, jekk huwa 1 Oxford
Triq jew 33 Oxford Street

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jew OX1 jew ox33, ikun x'ikun
dak l-indirizz numeriku huwa,

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star x hija l-dereferencing ta x.

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Allura jmorru f'dak l-indirizz u
mbagħad iwettqu l-għadd 42 hemmhekk.

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Allura li ikun
b'mod ekwivalenti ta 'tgħid li.

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Allura li kollox multa u mbagħad
aħna se jirrappreżentaw l-istampa

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kif ġej fejn konna miżjud
l 42 sa dik blokki ta 'erba

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bytes fuq il-lemin, imma
din il-linja kienet fejn l-affarijiet marru awry

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u l-kap Binky tal popped
off f'dan il-punt,

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minħabba affarijiet ħżiena jiġri meta
inti dereference valuri żibel

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jew inti dereference invalida
pointers, u jien ngħidlek invalida

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minħabba f'dan il-punt fil-
istorja, dak li hu ġewwa ta 'y?

128
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X'inhu l-valur tal y bbażati
fuq il-ftit passi passat?

129
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Yeah?

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Dak X'inhu?

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>> UDJENZA: An indirizz.

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DAVID Malan: An indirizz.

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Għandu jkun indirizz
imma jiena initialized dan?

134
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So I għadhom ma.

135
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Allura dak li hu magħruf li jkun fil hemmhekk?

136
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Huwa biss xi valur żibel.

137
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Dan jista 'jkun kwalunkwe indirizz minn żero sa
2 biljuni jekk għandek żewġ gigs ta 'RAM,

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jew żero għal 4 biljun jekk inti stajt
ltqajna erba gigabytes ta 'RAM.

139
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Huwa xi valur żibel,
iżda l-problema hija

140
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li s-sistema operattiva,
jekk ma jkunx tak

141
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li blokki ta 'memorja speċifikament
li inti qed tipprova tmur,

142
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huwa ġeneralment ser jikkawża dak
Rajna bħala tort segmentazzjoni.

143
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Allura fil-fatt, kwalunkwe fostkom li għadhom
tħabtu lejn problemi fil-ħinijiet uffiċċju

144
00:05:57,810 --> 00:06:00,393
jew problemi li l-aktar
ġeneralment ma jippruvaw figura

145
00:06:00,393 --> 00:06:02,150
tort segmentazzjoni,
li ġeneralment tfisser

146
00:06:02,150 --> 00:06:05,017
int jmissu segment ta
memorja li inti ma għandu jkun.

147
00:06:05,017 --> 00:06:07,350
Int jmissu memorja li
is-sistema operattiva ma jkunx

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inti permess għal mess, jekk huwa
billi esaġerata fil-firxa tiegħek

149
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jew li tibda issa, jekk
huwa għaliex int jmissu

150
00:06:12,870 --> 00:06:14,780
memorja li biss xi valur żibel.

151
00:06:14,780 --> 00:06:18,230
>> Allura tagħmel star x hawnhekk hija
tip ta 'mġiba mhux definiti.

152
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Inti qatt ma għandhom jagħmlu dan minħabba odds
huma, il-programm jinsab biss se crash,

153
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għaliex inti qed tgħid,
mur dan l-indirizz

154
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u inti għandek ebda idea fejn
dak l-indirizz fil-fatt hu.

155
00:06:27,000 --> 00:06:30,300
Għalhekk is-sistema operattiva huwa probabbli
ser crash program tiegħek

156
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bħala riżultat u tabilħaqq, dan huwa
dak li ġara hemm biex Binky.

157
00:06:33,840 --> 00:06:37,210
Allura finalment, Binky fiss
din il-problema ma 'dan.

158
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Allura dak il-programm innifsu kien difettuż.

159
00:06:38,909 --> 00:06:41,450
Imma jekk inti tip ta nimxu 'l quddiem
u jesegwixxi din il-linja minflok,

160
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y ugwali x ifisser biss x'ikun
address huwa x, wkoll poġġih fil y.

161
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>> U hekk pictorially, konna
rappreżentati dan b'żewġ vleġeġ

162
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minn x u mill tipponta y
l-istess post.

163
00:06:51,570 --> 00:06:55,760
Allura min-naħa semantika, x hija ugwali
li y peress li kemm ta 'dawk

164
00:06:55,760 --> 00:07:00,300
qed jaħżnu l-istess
indirizz, jimmiraw li tipponta lejn 42,

165
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u issa, meta inti tgħidli star
y, mur l-indirizz y,

166
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dan m'għandux effett sekondarju interessanti.

167
00:07:06,790 --> 00:07:10,320
Allura l-indirizz fl y hija l-
istess ħaġa bħat-indirizz fil x.

168
00:07:10,320 --> 00:07:15,060
Mela jekk inti tgħidli tmur għall-indirizz
fil y u jibdlu l-valur sa 13,

169
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li inkella huwa affettwat?

170
00:07:17,140 --> 00:07:21,100
X huwa, punt D, biex ngħidu hekk,
għandhomx jiġu affettwati wkoll.

171
00:07:21,100 --> 00:07:24,340
>> U fil-fatt, kif Nick ġibdet din l-istampa
fil claymation kien eżattament dan.

172
00:07:24,340 --> 00:07:28,665
Anki jekk aħna isegwu l-pointer
y, aħna spiċċajna fl-istess post,

173
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u hekk jekk konna biex jistampaw
out x jew pointee y, il

174
00:07:32,780 --> 00:07:35,720
allura aħna se tara l-valur ta '13.

175
00:07:35,720 --> 00:07:37,927
Issa, I say pointee li jkun
konsistenti mal-video.

176
00:07:37,927 --> 00:07:39,760
Programmaturi, li tiegħi
għarfien, qatt fil-fatt

177
00:07:39,760 --> 00:07:42,460
jiġifieri l-pointee kelma,
dak li huwa osservat

178
00:07:42,460 --> 00:07:44,650
fil, iżda għal konsistenza
mal-video, realizzata

179
00:07:44,650 --> 00:07:47,520
li kollox dan kien
fisser f'dik is-sitwazzjoni.

180
00:07:47,520 --> 00:07:54,190
Allura kwalnkwe kwistjoni dwar claymation
jew pointers jew malloc għadha biss?

181
00:07:54,190 --> 00:07:54,850
Nru?

182
00:07:54,850 --> 00:07:55,470
Kull dritt.

183
00:07:55,470 --> 00:07:58,560
>> Allura mingħajr aktar
dewmien, ejja tagħti ħarsa

184
00:07:58,560 --> 00:08:00,700
lejn fejn dan għandu fil-fatt
ġew użati għal xi żmien.

185
00:08:00,700 --> 00:08:03,580
Allura aħna kellna din il-librerija CS50
li ltqajna kollha ta 'dawn il-funzjonijiet.

186
00:08:03,580 --> 00:08:06,810
Imxejna użati GetInt ħafna, GetString,
probabbilment GetLongLong qabel

187
00:08:06,810 --> 00:08:09,840
fi PSet tiegħi wieħed jew hekk, imma
dak li fil-fatt ilu għaddej?

188
00:08:09,840 --> 00:08:12,920
Well, ejja tagħti ħarsa
taħt il-barnuża fi programm li

189
00:08:12,920 --> 00:08:17,017
tispira għaliex aħna nagħtuk l-CS50
librerija, u tabilħaqq mill-aħħar ġimgħa,

190
00:08:17,017 --> 00:08:18,850
bdejna teħid dawk
roti ta 'taħriġ off.

191
00:08:18,850 --> 00:08:21,080
Allura dan issa huwa magħżul
ta 'postmortem ta' dak

192
00:08:21,080 --> 00:08:23,690
ilu għaddej
ġewwa l-librerija CS50,

193
00:08:23,690 --> 00:08:27,250
anke jekk aħna issa se tibda miexja
bogħod minnha għal ħafna programmi.

194
00:08:27,250 --> 00:08:29,460
>> Allura dan huwa programm imsejjaħ scanf 0.

195
00:08:29,460 --> 00:08:30,510
Huwa super qasir.

196
00:08:30,510 --> 00:08:33,909
Hija biss għandha dawn il-linji, iżda
tintroduċi funzjoni msejħa scanf

197
00:08:33,909 --> 00:08:36,909
li aħna qed attwalment għaddejjin biex tara fil
mument ġewwa tal-librerija CS50,

198
00:08:36,909 --> 00:08:38,600
għalkemm f'forma kemmxejn differenti.

199
00:08:38,600 --> 00:08:41,330
Allura dan il-programm fuq il-linja 16
huwa li tiddikjara varjabbli x.

200
00:08:41,330 --> 00:08:43,150
Allura tagħti me erba 'bytes għal int.

201
00:08:43,150 --> 00:08:45,750
Huwa kien javżak utent,
numru jogħġbok, u mbagħad

202
00:08:45,750 --> 00:08:49,010
din hija linja interessanti li
attwalment torbot flimkien il-ġimgħa li għaddiet

203
00:08:49,010 --> 00:08:49,790
u dan.

204
00:08:49,790 --> 00:08:53,230
Scanf, u mbagħad tinnota li tieħu
string format, bħal printf,

205
00:08:53,230 --> 00:08:57,480
% i tfisser int, u mbagħad li tieħu
tieni argument li jistenna ftit

206
00:08:57,480 --> 00:08:58,260
funky.

207
00:08:58,260 --> 00:09:01,880
Huwa ampersand x, u li jiġi mfakkar,
rajna biss dan darba ġimgħa li għaddiet.

208
00:09:01,880 --> 00:09:03,465
Xi jfisser ampersand x jirrappreżenta?

209
00:09:03,465 --> 00:09:06,210

210
00:09:06,210 --> 00:09:08,450
X'jagħmel ampersand tagħmel C?

211
00:09:08,450 --> 00:09:08,950
Yeah?

212
00:09:08,950 --> 00:09:10,024
>> UDJENZA: L-indirizz ta '.

213
00:09:10,024 --> 00:09:11,190
DAVID Malan: L-indirizz ta '.

214
00:09:11,190 --> 00:09:13,190
Allura huwa l-oppost
tal-operatur stilla,

215
00:09:13,190 --> 00:09:17,270
billi l-operatur star jgħid, mur
dan l-indirizz, l-operatur ampersand

216
00:09:17,270 --> 00:09:20,280
jgħid, insemmu l-
indirizz ta 'dan il-varjabbli,

217
00:09:20,280 --> 00:09:23,530
u għalhekk dan huwa importanti, għaliex
iskop scanf fil-ħajja

218
00:09:23,530 --> 00:09:26,320
huwa li skennjati l-utent tal
kontribut mill-keyboard,

219
00:09:26,320 --> 00:09:29,970
jiddependi fuq xi hu jew hi
tipi, u mbagħad jaqra input li utent

220
00:09:29,970 --> 00:09:32,970
fi varjabbli, imma aħna
raw fl-aħħar ġimgħatejn

221
00:09:32,970 --> 00:09:36,080
li dik il-funzjoni tpartit li aħna
ppruvaw sforz biex jimplimentaw

222
00:09:36,080 --> 00:09:37,110
kien biss imkisser.

223
00:09:37,110 --> 00:09:42,470
Ifakkar li bil-funzjoni tpartit,
jekk aħna biss iddikjarati A u B kif ints,

224
00:09:42,470 --> 00:09:47,040
għamilna b'suċċess tpartit l-
żewġ varjabbli ġewwa tal swap

225
00:09:47,040 --> 00:09:50,080
bħad bil-ħalib u ĠU
iżda hekk kif swap lura,

226
00:09:50,080 --> 00:09:55,200
dak li kien ir-riżultat fir-rigward
li x uy, il-valuri oriġinali?

227
00:09:55,200 --> 00:09:55,700
Xejn.

228
00:09:55,700 --> 00:09:56,200
Yeah.

229
00:09:56,200 --> 00:09:59,754
Xejn ġara dak iż-żmien, minħabba
swaps tinbidel biss kopji lokali tiegħu,

230
00:09:59,754 --> 00:10:01,670
li fi kliem ieħor, kull
dan iż-żmien, kull meta konna

231
00:10:01,670 --> 00:10:04,010
qed jittrasferixxu fl-argumenti
funzjonijiet, aħna qed

232
00:10:04,010 --> 00:10:05,939
biss tgħaddi kopji ta 'dawn l-argumenti.

233
00:10:05,939 --> 00:10:07,980
Tista 'tagħmel ma' dak
xi trid magħhom,

234
00:10:07,980 --> 00:10:10,890
iżda dawn qed tmur biex ikollhom l-ebda
effett fuq il-valuri oriġinali.

235
00:10:10,890 --> 00:10:13,650
Allura dan huwa problematiku jekk inti
jridu li jkollhom funzjoni simili scanf

236
00:10:13,650 --> 00:10:17,170
fil-ħajja, li l-għan huwa li scan
input-utent mill-keyboard

237
00:10:17,170 --> 00:10:22,010
u mbagħad imla l-vojt, hekk li
jitkellmu, jiġifieri, jagħti varjabbli bħal x

238
00:10:22,010 --> 00:10:25,410
valur, għaliex jekk jien kienu
għal ftit jgħaddu x biex scanf,

239
00:10:25,410 --> 00:10:28,790
jekk inti tikkunsidra l-loġika ta 'l-aħħar
ġimgħa, scanf tista 'tagħmel dak kollu li trid

240
00:10:28,790 --> 00:10:33,100
ma 'kopja ta x, iżda ma setgħux
b'mod permanenti bidla x sakemm nagħtu

241
00:10:33,100 --> 00:10:37,120
scanf mappa teżor, biex ngħidu hekk,
fejn x jimmarka l-post, fejn

242
00:10:37,120 --> 00:10:41,860
aħna jgħaddu fil-indirizz ta 'X sabiex
scanf tista 'tmur hemm u fil-fatt bidla

243
00:10:41,860 --> 00:10:42,920
il-valur ta 'x.

244
00:10:42,920 --> 00:10:45,080
U hekk fil-fatt, kollha
li dan il-programm ma

245
00:10:45,080 --> 00:10:53,180
jekk nagħmel scanf 0, fis-sors tiegħi
Direttorju 5m, jagħmlu scanf 0,

246
00:10:53,180 --> 00:10:57,730
dot mmejla scanf, numru
jekk jogħġbok 50, grazzi għall-50.

247
00:10:57,730 --> 00:11:01,020
>> Allura huwa mhux kollha li interessanti,
imma dak li tassew qed jiġri

248
00:11:01,020 --> 00:11:04,820
hija li hekk kif I call
scanf hawn, il-valur ta 'x

249
00:11:04,820 --> 00:11:06,410
qed jiġi permanentement.

250
00:11:06,410 --> 00:11:08,335
Issa, dan jidher sbieħ u
tajba, u fil-fatt,

251
00:11:08,335 --> 00:11:11,200
Jidher bħal aħna ma verament bżonn
il-librerija CS50 fil-livelli kollha aktar.

252
00:11:11,200 --> 00:11:13,960
Per eżempju, ejja jimxu
dan darba aktar hawn.

253
00:11:13,960 --> 00:11:15,750
Let me terġa 'dan għat-tieni.

254
00:11:15,750 --> 00:11:20,600
Ejja nippruvaw numru jogħġbok u
Minflok qal 50 bħal qabel,

255
00:11:20,600 --> 00:11:22,810
ejja biss jgħidu le.

256
00:11:22,810 --> 00:11:24,000
OK, dan huwa ftit stramb.

257
00:11:24,000 --> 00:11:25,270
KOLLOX SEW.

258
00:11:25,270 --> 00:11:28,680
U biss ftit nonsense hawn.

259
00:11:28,680 --> 00:11:31,170
Għalhekk ma jidhirx li
jimmaniġġjaw sitwazzjonijiet żbaljati.

260
00:11:31,170 --> 00:11:33,620
Għalhekk għandna bżonn li minimament bidu
jżid xi żball iċċekkjar-

261
00:11:33,620 --> 00:11:37,460
biex tiżgura li l-utent ikollu
ittajpjat fil numru attwali bħall 50,

262
00:11:37,460 --> 00:11:40,720
minħabba kliem apparentement typing
ma jinsabx bħala problematiċi,

263
00:11:40,720 --> 00:11:42,020
iżda probabbilment għandu jkun.

264
00:11:42,020 --> 00:11:46,450
>> Ejja nħarsu lejn din il-verżjoni issa li l-
tentattiv tiegħi biex reimplement GetString.

265
00:11:46,450 --> 00:11:48,437
Jekk scanf għandha dan kollu
funzjonalità mibnija,

266
00:11:48,437 --> 00:11:51,270
għaliex li aħna ġew dabbling ma 'dawn
roti ta 'taħriġ bħal GetString?

267
00:11:51,270 --> 00:11:55,450
Well, hawnhekk huwa forsi tiegħi stess
Verżjoni sempliċi ta 'GetString

268
00:11:55,450 --> 00:12:00,766
li biha ġimgħa ilu, I jista 'jkollhom qal,
tagħti me a string u sejħa hija buffer.

269
00:12:00,766 --> 00:12:03,390
Illum, jien ser tibda biss
qal star char, li, irtirar,

270
00:12:03,390 --> 00:12:04,400
huwa biss sinonimi.

271
00:12:04,400 --> 00:12:06,629
Huwa jistenna scarier iżda huwa
l-istess ħaġa eżatt.

272
00:12:06,629 --> 00:12:09,420
Allura tagħti me a varjabbli imsejjaħ buffer
li għaddej biex jaħżnu string,

273
00:12:09,420 --> 00:12:12,780
tell-sekwenza utent jekk jogħġbok,
u mbagħad, bħad qabel,

274
00:12:12,780 --> 00:12:17,760
ejja tipprova li jissellef din il-lezzjoni scanf
% s dan iż-żmien u mbagħad jgħaddu fi buffer.

275
00:12:17,760 --> 00:12:19,310
Issa, verifika sanità malajr.

276
00:12:19,310 --> 00:12:22,120
Why am I ma tgħid
ampersand buffer dan iż-żmien?

277
00:12:22,120 --> 00:12:25,190

278
00:12:25,190 --> 00:12:26,625
Jiddeduċu mill-eżempju preċedenti.

279
00:12:26,625 --> 00:12:28,000
UDJENZA: Char star huwa pointer.

280
00:12:28,000 --> 00:12:29,920
DAVID Malan: Eżattament,
minħabba dan iż-żmien, char

281
00:12:29,920 --> 00:12:34,080
star huwa diġà pointer, indirizz,
billi definizzjoni ta 'dak star jkunu hemm.

282
00:12:34,080 --> 00:12:37,530
U jekk scanf jistenna indirizz,
huwa biżżejjed biss biex jgħaddu fi buffer.

283
00:12:37,530 --> 00:12:39,260
I m'għandhomx bżonn li jgħidu buffer ampersand.

284
00:12:39,260 --> 00:12:42,177
Għall-kurjuż, inti tista
tagħmel xi ħaġa bħal din.

285
00:12:42,177 --> 00:12:43,510
Dan ikollu tifsira differenti.

286
00:12:43,510 --> 00:12:47,240
Dan se jagħtuk pointer
għal pointer, li huwa attwalment

287
00:12:47,240 --> 00:12:50,050
ħaġa valida C, iżda għal
issa, ejja jżommha sempliċi

288
00:12:50,050 --> 00:12:51,750
u jżommu l-istorja konsistenti.

289
00:12:51,750 --> 00:12:54,100
Jien biss ser jgħaddu fil
buffer u li korretta.

290
00:12:54,100 --> 00:12:56,487
Il-problema għalkemm hija din.

291
00:12:56,487 --> 00:12:58,820
Let me imorru quddiem u run dan
programm wara kompilazzjoni tagħha.

292
00:12:58,820 --> 00:13:00,902
Jagħmlu scanf 1.

293
00:13:00,902 --> 00:13:02,610
Indanna dan, kompilatur tiegħi
qbid żball tiegħi.

294
00:13:02,610 --> 00:13:04,090
Agħti me-tieni waħda.

295
00:13:04,090 --> 00:13:05,460
Clang.

296
00:13:05,460 --> 00:13:06,990
Ejja ngħidu scanf-1.c.

297
00:13:06,990 --> 00:13:10,880

298
00:13:10,880 --> 00:13:11,380
KOLLOX SEW.

299
00:13:11,380 --> 00:13:12,720
Hemm immorru.

300
00:13:12,720 --> 00:13:14,280
Ghandi bzonnha.

301
00:13:14,280 --> 00:13:16,750
CS50 ID għandha diversi
settings tal-konfigurazzjoni

302
00:13:16,750 --> 00:13:18,280
li tipproteġik kontra lilek innifsek.

303
00:13:18,280 --> 00:13:21,300
I meħtieġa biex jiskonnettja dawk mill
running clang manwalment dan iż-żmien.

304
00:13:21,300 --> 00:13:22,140
Allura string jekk jogħġbok.

305
00:13:22,140 --> 00:13:25,560
Jien ser jimxi 'l quddiem u t-tip
fid-dinja bonjour favorit tiegħi.

306
00:13:25,560 --> 00:13:26,490
OK, nulli.

307
00:13:26,490 --> 00:13:27,700
Li mhux dak I ittajpjat.

308
00:13:27,700 --> 00:13:29,690
Allura huwa indikattiv ta '
xi ħaġa li tkun ħażina.

309
00:13:29,690 --> 00:13:33,920
Let me imorru quddiem u t-tip
fi string verament twila.

310
00:13:33,920 --> 00:13:37,210
Grazzi għall-null u jien ma nafx
jekk jien ser tkun kapaċi li jikkraxxja dan.

311
00:13:37,210 --> 00:13:40,240
Ejja nippruvaw kopja ftit
pasta u ara jekk dan jgħin.

312
00:13:40,240 --> 00:13:43,290
Just paste ħafna ta 'dan.

313
00:13:43,290 --> 00:13:47,310
Huwa definittivament akbar
string mis-soltu.

314
00:13:47,310 --> 00:13:51,450
Ejja biss verament tikteb.

315
00:13:51,450 --> 00:13:51,950
No

316
00:13:51,950 --> 00:13:52,650
Kkritikat dan.

317
00:13:52,650 --> 00:13:53,480
Kmand ma nstabx.

318
00:13:53,480 --> 00:13:54,550
Allura dak mhux relatati.

319
00:13:54,550 --> 00:13:56,440
Dan għaliex I pasted
xi karattri ħżiena,

320
00:13:56,440 --> 00:13:59,780
iżda dan jirriżulta mhux sejjer jaħdem.

321
00:13:59,780 --> 00:14:03,510
>> Ejja nippruvaw dan darba aktar, minħabba
huwa aktar gost jekk għandna attwalment crash dan.

322
00:14:03,510 --> 00:14:09,116
Ejja tip dan u issa, jien
ser kopja string verament twila

323
00:14:09,116 --> 00:14:10,990
u issa ejja ara jekk irridu
jista crash dan il-ħaġa.

324
00:14:10,990 --> 00:14:14,235
Avviż I jitħalla barra l-ispazji u
linji ġodda u semicolons

325
00:14:14,235 --> 00:14:16,035
u l-karattri funky kollha.

326
00:14:16,035 --> 00:14:16,535
Ikteb.

327
00:14:16,535 --> 00:14:21,090

328
00:14:21,090 --> 00:14:22,880
U issa l-network jinsab biss li bil-mod.

329
00:14:22,880 --> 00:14:27,460
I miżmum Kmand-V twil wisq, b'mod ċar.

330
00:14:27,460 --> 00:14:28,190
Kkritikat dan!

331
00:14:28,190 --> 00:14:29,260
Kmand ma nstabx.

332
00:14:29,260 --> 00:14:29,780
>> KOLLOX SEW.

333
00:14:29,780 --> 00:14:32,240
Ukoll, il-punt huwa
madankollu dawn li ġejjin.

334
00:14:32,240 --> 00:14:36,910
Allura dak li huwa attwalment għaddejjin
fuq din id-dikjarazzjoni ma

335
00:14:36,910 --> 00:14:39,240
tal char buffer star fuq il-linja 16?

336
00:14:39,240 --> 00:14:41,820
Allura dak am I jkollna
meta I tiddikjara pointer?

337
00:14:41,820 --> 00:14:47,440
All jien jkollna huwa valur erba byte
imsejħa buffer, imma x'hemm ġewwa ta 'dan

338
00:14:47,440 --> 00:14:49,540
fil-mument?

339
00:14:49,540 --> 00:14:50,930
Huwa biss xi valur żibel.

340
00:14:50,930 --> 00:14:54,170
Minħabba li kwalunkwe ħin li inti tiddikjara varjabbli
fis-C, huwa biss xi valur żibel,

341
00:14:54,170 --> 00:14:56,220
u aħna qed jibdew
vjaġġ fuq din ir-realtà.

342
00:14:56,220 --> 00:14:59,720
Issa, meta I tell scanf,
mur dan l-indirizz

343
00:14:59,720 --> 00:15:01,520
u tpoġġi kwalunkwe t-tipi utent fil.

344
00:15:01,520 --> 00:15:06,400
Jekk it-tipi utent fil bonjour
dinja, ukoll, fejn ma nressaq dan?

345
00:15:06,400 --> 00:15:07,750
Buffer hija valur żibel.

346
00:15:07,750 --> 00:15:11,510
>> Allura dak it-tip ta 'prodotti simili vleġġa
li l-tipponta li jaf fejn.

347
00:15:11,510 --> 00:15:13,880
Forsi huwa tipponta
dritt hawn fil-memorja tiegħi.

348
00:15:13,880 --> 00:15:16,560
U hekk meta l-utent
tipi fil bonjour dinja,

349
00:15:16,560 --> 00:15:22,380
il-programm jipprova jagħmel l-
string bonjour dinja backslash 0

350
00:15:22,380 --> 00:15:23,910
f'dak blokki ta 'memorja.

351
00:15:23,910 --> 00:15:27,070
Iżda bi probabbiltà għolja, iżda
ċar mhux 100% probabbiltà,

352
00:15:27,070 --> 00:15:30,440
il-kompjuter se mbagħad crash
il-programm għaliex din m'hijiex

353
00:15:30,440 --> 00:15:32,490
memorja I għandhom jitħallew għall-mess.

354
00:15:32,490 --> 00:15:36,330
Allura fil-qosor, dan il-programm huwa
difettuż għal eżattament dik ir-raġuni.

355
00:15:36,330 --> 00:15:38,070
Jien fundamentalment ma nagħmilx dak?

356
00:15:38,070 --> 00:15:42,366
Liema passi għandhom I titħalla barra, bħad
aħna jitħalla barra bil ewwel eżempju Binky tal?

357
00:15:42,366 --> 00:15:42,866
Yeah?

358
00:15:42,866 --> 00:15:43,710
>> UDJENZA: allokazzjoni Memorja?

359
00:15:43,710 --> 00:15:45,001
>> DAVID Malan: allokazzjoni Memorja.

360
00:15:45,001 --> 00:15:48,400
I ma attwalment allokati
kwalunkwe memorja għal dak string.

361
00:15:48,400 --> 00:15:50,270
Allura nistgħu jiffissaw dan fi ftit ta 'modi.

362
00:15:50,270 --> 00:15:52,700
Wieħed, nistgħu jżommha sempliċi
u fil-fatt, issa int

363
00:15:52,700 --> 00:15:55,116
ser tibda biex tara imċajpra
tal-linji bejn dak

364
00:15:55,116 --> 00:15:58,520
firxa hija, dak string hija, dak li
star char hija, dak firxa ta 'Chars

365
00:15:58,520 --> 00:15:59,020
hu.

366
00:15:59,020 --> 00:16:02,450
Hawn tieni eżempju
jinvolvu kordi u avviż

367
00:16:02,450 --> 00:16:05,690
kollha I ghamilt fuq il-linja
16 huwa, minflok ta 'tgħid

368
00:16:05,690 --> 00:16:09,530
li buffer se jkun char
star, pointer għal blokki ta 'memorja,

369
00:16:09,530 --> 00:16:14,057
Jien ser tagħti b'mod proattiv ħafna
myself buffer għal 16 karattri,

370
00:16:14,057 --> 00:16:16,390
u fil-fatt, jekk int familjari
mal-buffering tul,

371
00:16:16,390 --> 00:16:20,570
probabbilment mid-dinja ta 'videos,
fejn video huwa lqugħ, buffering,

372
00:16:20,570 --> 00:16:21,175
buffering.

373
00:16:21,175 --> 00:16:22,550
Ukoll, x'inhu l-konnessjoni hawn?

374
00:16:22,550 --> 00:16:24,960
Ukoll, Ġewwa l YouTube
u ġewwa ta 'video players

375
00:16:24,960 --> 00:16:27,200
ġeneralment huwa firxa
li l-akbar minn 16.

376
00:16:27,200 --> 00:16:30,340
Jista 'jkun firxa ta' daqs wieħed
megabyte, forsi 10 megabytes,

377
00:16:30,340 --> 00:16:34,330
u f'dak firxa ma browser tiegħek
tniżżel mazz sħiħ ta 'bytes,

378
00:16:34,330 --> 00:16:37,500
mazz sħiħ ta 'megabytes ta'
video, u l-plejer video,

379
00:16:37,500 --> 00:16:40,930
Tal YouTube jew min i, jibda
qari tal-bytes minn dak array,

380
00:16:40,930 --> 00:16:43,530
u kwalunkwe ħin li inti tara l-
buffering kelma, buffering,

381
00:16:43,530 --> 00:16:46,350
dan ifisser l-attur għandu
gotten sal-aħħar ta 'dak array.

382
00:16:46,350 --> 00:16:50,430
In-netwerk tant huwa baxx li ma jkunx
mimlija mill-ġdid il-firxa b'aktar bytes

383
00:16:50,430 --> 00:16:55,610
u għalhekk int minn bits
li juri lill-utent.

384
00:16:55,610 --> 00:16:59,430
>> Allura buffer huwa terminu apt hawn f'dik
huwa biss firxa, blokki ta 'memorja.

385
00:16:59,430 --> 00:17:02,530
U dan se tiffissa lilha
għaliex jirriżulta

386
00:17:02,530 --> 00:17:07,410
li inti jista 'jikkura arrays daqslikieku
huma indirizzi, anki jekk buffer

387
00:17:07,410 --> 00:17:10,710
huwa biss simbolu, huwa
sekwenza ta 'karattri, buffer,

388
00:17:10,710 --> 00:17:14,760
dan huwa utli għalija, l-programmer,
inti tista 'tgħaddi l-isem tagħha madwar

389
00:17:14,760 --> 00:17:17,079
bħallikieku kienet
pointer, daqs li kieku

390
00:17:17,079 --> 00:17:21,000
kienu l-indirizz ta 'blokki
ta 'memorja għal 16 Chars.

391
00:17:21,000 --> 00:17:24,530
Allura dak li ngħid, I jistgħu jgħaddu
l scanf eżattament din il-kelma

392
00:17:24,530 --> 00:17:30,670
u hekk issa, jekk I jagħmlu dan il-programm,
jagħmlu scanf 2, dot slash scanf 2,

393
00:17:30,670 --> 00:17:35,386
u tip bonjour dinja,
Daħħal, li time--

394
00:17:35,386 --> 00:17:37,590
>> Hmm, dak li ġara?

395
00:17:37,590 --> 00:17:39,340
String jekk jogħġbok.

396
00:17:39,340 --> 00:17:41,430
What did I do wrong?

397
00:17:41,430 --> 00:17:43,800
Hello dinja, buffer.

398
00:17:43,800 --> 00:17:44,705
Hello dinja.

399
00:17:44,705 --> 00:17:48,201

400
00:17:48,201 --> 00:17:49,420
Ah, I know dak li qed jagħmel.

401
00:17:49,420 --> 00:17:49,920
KOLLOX SEW.

402
00:17:49,920 --> 00:17:51,628
Allura huwa qari
sa l-ewwel ispazju.

403
00:17:51,628 --> 00:17:55,680
Mela ejja iqarrqu għal ftit mument u
jgħidu I biss riedu xi ħaġa tip

404
00:17:55,680 --> 00:18:01,408
verament twila bħal din hija sentenza twila
li l-waħda, tnejn, tlieta, erba ', ħames,

405
00:18:01,408 --> 00:18:04,420
sitt, seba ', tmien, disa',
10, 11, 12, 13, 14, 15, 16.

406
00:18:04,420 --> 00:18:05,300
KOLLOX SEW.

407
00:18:05,300 --> 00:18:07,600
Huwa tabilħaqq sentenza twila.

408
00:18:07,600 --> 00:18:10,710
Allura din is-sentenza hija
itwal minn 16 karattru

409
00:18:10,710 --> 00:18:13,670
u għalhekk meta I hit Ikteb,
x'inhu jiġri?

410
00:18:13,670 --> 00:18:16,940
Ukoll, f'dan il-każ tal-
buffer istorja, I kien iddikjara

411
00:18:16,940 --> 00:18:22,190
li attwalment qed firxa
ma '16 Chars lesta li tmur.

412
00:18:22,190 --> 00:18:27,426
Allura wieħed, tnejn, tlieta, erba ', ħames, sitt,
seba ', tmien, disa', 10, 11, 12, 13, 14,

413
00:18:27,426 --> 00:18:29,440
15, 16.

414
00:18:29,440 --> 00:18:34,410
Allura 16 karattri, u issa, meta I
jinqraw xi ħaġa bħal din hija twila

415
00:18:34,410 --> 00:18:43,950
sentenza, dak li jiġri huwa
li jien ser jinqraw dan huwa twil

416
00:18:43,950 --> 00:18:49,660
S-E-N-T-E-N-C-E, sentenza.

417
00:18:49,660 --> 00:18:52,270
>> Allura dan huwa deliberatament
ħaġa ħażina li I

418
00:18:52,270 --> 00:18:55,060
iżommu kitba lil hinn mill-
konfini ta 'firxa tiegħi,

419
00:18:55,060 --> 00:18:56,660
lil hinn mill-konfini ta 'buffer tiegħi.

420
00:18:56,660 --> 00:19:00,100
I jistgħu jiksbu xortik tajba u l-programm
ser iżżomm fuq tmexxija u ma 'kura,

421
00:19:00,100 --> 00:19:03,450
iżda ġeneralment, dan
tabilħaqq se tiġrifa programm tiegħi,

422
00:19:03,450 --> 00:19:06,440
u huwa bug fil tiegħi
kodiċi l-mument I pass

423
00:19:06,440 --> 00:19:08,576
lil hinn mill-konfini
ta 'dak array, minħabba I

424
00:19:08,576 --> 00:19:10,450
ma nafx jekk huwa
neċessarjament ser crash

425
00:19:10,450 --> 00:19:12,120
jew jekk jien biss se tikseb xxurtjati.

426
00:19:12,120 --> 00:19:15,750
Allura dan huwa problematiku għaliex
F'dan il-każ, dan ma jidhirx li jaħdmu

427
00:19:15,750 --> 00:19:20,931
u ejja tentar destin hawn, anke jekk
l IDE jidher li jittolleraw pjuttost ftit

428
00:19:20,931 --> 00:19:21,430
of--

429
00:19:21,430 --> 00:19:22,040
>> Hemm immorru.

430
00:19:22,040 --> 00:19:23,240
Fl-aħħarnett.

431
00:19:23,240 --> 00:19:26,470
Hekk jien l-unika waħda li tista 'tara dan.

432
00:19:26,470 --> 00:19:29,630
So I biss kellhom ħafna gost ittajpjar
out frażi attwali verament twila

433
00:19:29,630 --> 00:19:32,800
li ċertament qabżet
16 bytes, minħabba I

434
00:19:32,800 --> 00:19:38,050
ittajpjat f'dan multi-linja twila crazy
frażi, u mbagħad avviż dak li ġara.

435
00:19:38,050 --> 00:19:41,110
Il-programm ppruvaw-istampar
u mbagħad ltqajna tort segmentazzjoni

436
00:19:41,110 --> 00:19:44,430
u difetti segmentazzjoni huwa meta
xi ħaġa bħal din jiġri

437
00:19:44,430 --> 00:19:47,650
u s-sistema operattiva jgħid
Le, ma jistax imiss li l-memorja.

438
00:19:47,650 --> 00:19:49,570
Aħna qed tmur biex joqtlu
il-programm għal kollox.

439
00:19:49,570 --> 00:19:51,180
>> Allura dan jidher problematiku.

440
00:19:51,180 --> 00:19:54,540
Stajt mtejba tal-programm li permezz tiegħu
inqas ikollhom xi memorja,

441
00:19:54,540 --> 00:19:58,000
iżda dan jidher li tillimita
l GetString funzjoni li jkollna

442
00:19:58,000 --> 00:20:00,780
spag ta 'xi tul finiti 16.

443
00:20:00,780 --> 00:20:04,200
Mela jekk inti tixtieq li tappoġġja itwal
sentenzi minn 16 karattri,

444
00:20:04,200 --> 00:20:04,880
liema do you do?

445
00:20:04,880 --> 00:20:07,970
Well, inti tista 'żżid l-
daqs ta 'dan buffer sa 32

446
00:20:07,970 --> 00:20:09,190
jew li jidher tip ta 'qasir.

447
00:20:09,190 --> 00:20:12,260
Għaliex ma aħna biss tagħmel
huwa 1,000 iżda timbotta lura.

448
00:20:12,260 --> 00:20:17,100
X'hemm-rispons intuwittivament ta
biss jevitaw din il-problema billi tagħmel

449
00:20:17,100 --> 00:20:20,660
buffer tiegħi akbar, bħal 1,000 Chars?

450
00:20:20,660 --> 00:20:23,470
Bl-implimentazzjoni GetString b'dan il-mod.

451
00:20:23,470 --> 00:20:27,130
X'hemm tajjeb jew ħażin hawn?

452
00:20:27,130 --> 00:20:28,033
Yeah?

453
00:20:28,033 --> 00:20:30,574
UDJENZA: Jekk inti torbot up a lott
ta 'spazju u inti ma tużah,

454
00:20:30,574 --> 00:20:33,500
allura inti ma tistax talloka mill-ġdid dak l-ispazju.

455
00:20:33,500 --> 00:20:34,500
DAVID Malan: Assolutament.

456
00:20:34,500 --> 00:20:38,480
Huwa ħela b'tali mod li jekk inti ma
attwalment ħtieġa 900 ta 'dawk bytes

457
00:20:38,480 --> 00:20:41,057
u għadhom inti qed tistaqsi għal
1000 b'kollox xorta,

458
00:20:41,057 --> 00:20:44,140
int biss jikkunsmaw memorja aktar fuq
kompjuter l-utent milli għandek bżonn,

459
00:20:44,140 --> 00:20:45,740
u wara kollox, xi wħud
inti stajt diġà ltaqgħu magħhom

460
00:20:45,740 --> 00:20:47,620
fil-ħajja li meta int
running lottijiet ta 'programmi

461
00:20:47,620 --> 00:20:50,470
u dawn qed tiekol lottijiet ta 'memorja,
dan jista 'attwalment jkollhom impatt prestazzjoni

462
00:20:50,470 --> 00:20:52,220
u l-esperjenza l-utent
fuq il-kompjuter.

463
00:20:52,220 --> 00:20:56,090
Allura dak it-tip ta 'soluzzjoni għażżien,
għall-żgur, u bil-maqlub,

464
00:20:56,090 --> 00:21:00,140
huwa mhux biss ħalja, liema problema
xorta jibqa ', anke jekk nagħmel buffer tiegħi

465
00:21:00,140 --> 00:21:02,100
1000?

466
00:21:02,100 --> 00:21:02,600
Yeah?

467
00:21:02,600 --> 00:21:04,475
>> UDJENZA: Il-sekwenza huwa tul 1001.

468
00:21:04,475 --> 00:21:05,350
DAVID Malan: Eżattament.

469
00:21:05,350 --> 00:21:08,280
Jekk string tiegħek huwa t-tul 1001,
inti għandek l-istess problema eżatt,

470
00:21:08,280 --> 00:21:10,705
u billi argument tiegħi, nixtieq
biss imbagħad jagħmilha 2000,

471
00:21:10,705 --> 00:21:12,830
imma ma tafx fil
quddiem kemm hu kbir għandu jkun,

472
00:21:12,830 --> 00:21:16,890
u għadhom, I do jkollhom biex jikkompilaw programm tiegħi
qabel kiri nies jużaw u download

473
00:21:16,890 --> 00:21:17,390
it.

474
00:21:17,390 --> 00:21:21,490
Allura dan huwa eżattament it-tip ta '
Jittieħed li l jipprova librerija CS50

475
00:21:21,490 --> 00:21:24,750
biex tgħinna ma 'u aħna ser biss t'għajn
lejn uħud mill-implimentazzjoni sottostanti

476
00:21:24,750 --> 00:21:29,790
hawn, iżda dan huwa CS50 dot C. Dan
huwa l-fajl li kien fuq CS50 IDE

477
00:21:29,790 --> 00:21:31,420
dawn il-ġimgħat kollha li inti kont qed tuża.

478
00:21:31,420 --> 00:21:34,280
Huwa pre-ikkumpilata u inti stajt
ilhom jużawha awtomatikament

479
00:21:34,280 --> 00:21:38,780
min-natura ta 'wara l-
sing L-bandiera CS50 ma clang,

480
00:21:38,780 --> 00:21:42,300
imma jekk jien iscroll down kollha permezz ta '
dawn il-funzjonijiet, hawn GetString,

481
00:21:42,300 --> 00:21:44,636
u biss biex jagħtuk
togħma ta 'x'inhu għaddej,

482
00:21:44,636 --> 00:21:46,760
ejja tagħti ħarsa lejn
il-kumplessità relattiva.

483
00:21:46,760 --> 00:21:48,870
Mhuwiex super twil
funzjoni, iżda aħna ma

484
00:21:48,870 --> 00:21:52,530
għandek biex jaħsbu iebes dwar
kif għanddu jkollna kordi.

485
00:21:52,530 --> 00:21:55,660
>> Allura hawnhekk buffer tiegħi u I
apparentement initialize lill null.

486
00:21:55,660 --> 00:21:57,990
Dan, naturalment, huwa l-
istess ħaġa bħat star char,

487
00:21:57,990 --> 00:22:00,585
imma I iddeċieda fil
implimentazzjoni tal-librerija CS50

488
00:22:00,585 --> 00:22:02,460
li jekk aħna qed tmur biex
ikunu kompletament dinamiku,

489
00:22:02,460 --> 00:22:05,770
I do not know bil-quddiem kemm hu kbir ta '
utenti string se rridu nġibu.

490
00:22:05,770 --> 00:22:08,140
Hekk jien ser tibda
mal biss string vojta

491
00:22:08,140 --> 00:22:11,507
u jien ser jibnu kemm
memorja kif għandi bżonn biex jitwaħħal il-string utent

492
00:22:11,507 --> 00:22:13,340
u jekk jien ma jkollhom
biżżejjed, jien ser jistaqsu

493
00:22:13,340 --> 00:22:15,010
is-sistema operattiva għall-memorja aktar.

494
00:22:15,010 --> 00:22:17,510
Jien ser jimxu string tagħhom
fi blokki akbar ta 'memorja

495
00:22:17,510 --> 00:22:21,847
u jien ser jirrilaxxa jew ħielsa l
blokki kbar biżżejjed ta 'memorja

496
00:22:21,847 --> 00:22:23,680
u aħna qed biss jmorru
biex jagħmlu dan iteratively.

497
00:22:23,680 --> 00:22:25,570
>> Allura t'għajn malajr,
here biss varjabbli

498
00:22:25,570 --> 00:22:28,780
li magħhom Jien ser iżżomm kont
tal-kapaċità tal buffer tiegħi.

499
00:22:28,780 --> 00:22:30,071
Kemm bytes nista tajbin?

500
00:22:30,071 --> 00:22:32,070
Hawn n varjabbli
li jien ser iżommu

501
00:22:32,070 --> 00:22:36,200
rekord ta 'kemm bytes huma attwalment
l buffer jew li l-utent ikun ittajpjat.

502
00:22:36,200 --> 00:22:39,900
Jekk inti stajt ma bbenefikawx dan qabel, inti
tista 'tispeċifika li varjabbli bħal int

503
00:22:39,900 --> 00:22:46,370
huwa mhux iffirmat, li kif tissuġġerixxi l-isem,
ifisser li huwa mhux negattivi, u għaliex kieku

504
00:22:46,370 --> 00:22:50,590
I qatt trid li jolqot tispeċifika
li int mhix sempliċement int,

505
00:22:50,590 --> 00:22:52,540
iżda huwa ta 'int mhux iffirmat?

506
00:22:52,540 --> 00:22:55,064
Huwa int mhux negattiv.

507
00:22:55,064 --> 00:22:56,355
X'tagħmel l-[inaudible] jfisser?

508
00:22:56,355 --> 00:22:58,910
>> UDJENZA: Huwa jiddeskrivi ammont
ta 'memorja li tista' tkun [inaudible].

509
00:22:58,910 --> 00:22:59,660
>> DAVID Malan: Yeah.

510
00:22:59,660 --> 00:23:03,710
Mela jekk jien ngħid mhux iffirmat, dan huwa attwalment
giving you waħda daqsxejn ta 'memorja extra

511
00:23:03,710 --> 00:23:07,440
u jidher tip ta 'iblah, imma jekk inti
jkollhom waħda daqsxejn ta 'memorja addizzjonali, li

512
00:23:07,440 --> 00:23:09,940
ifisser li inti għandek doppju
Valuri inti tista jirrappreżentaw,

513
00:23:09,940 --> 00:23:11,570
għaliex jista 'jkun ta' 0 jew 1.

514
00:23:11,570 --> 00:23:14,660
Allura awtomatikament, l-int tista 'tkun bejn wieħed u ieħor
negattiv 2 biljuni it-triq kollha

515
00:23:14,660 --> 00:23:16,030
sa pożittiv 2 biljuni.

516
00:23:16,030 --> 00:23:18,540
Dawk huma firxiet kbar, iżda
huwa għadu tip ta 'ħela

517
00:23:18,540 --> 00:23:21,280
jekk inti biss jimpurtahom
daqsijiet, li biss intuwittivament

518
00:23:21,280 --> 00:23:24,620
għandhom ikunu non-negattiv jew
pożittiva jew 0, tajjeb allura,

519
00:23:24,620 --> 00:23:28,884
għaliex huma inti ħela 2 biljuni
valuri possibbli għal numri negattivi

520
00:23:28,884 --> 00:23:30,300
jekk int qatt ser tuża minnhom?

521
00:23:30,300 --> 00:23:35,350
Allura billi qal mhux iffirmat, issa int tista tiegħi
jkun bejn 0 u madwar 4 biljun.

522
00:23:35,350 --> 00:23:39,280
>> Allura hawnhekk biss int C għal raġunijiet
aħna mhux se jsibu rwieħhom biss issa kif

523
00:23:39,280 --> 00:23:42,280
għaliex huwa ta 'int minflok
ta 'char, iżda hawnhekk huwa

524
00:23:42,280 --> 00:23:44,630
l-gist ta 'dak li għaddej
fuq, u xi wħud minnkom

525
00:23:44,630 --> 00:23:48,340
jista 'jkun bl-użu, per eżempju, il-
funzjoni fgetc anki fil PSet erba

526
00:23:48,340 --> 00:23:51,580
jew wara, aħna ser tara
għal darb'oħra fl problema stabbiliti ħamsa,

527
00:23:51,580 --> 00:23:55,410
fgetc huwa sbieħ għaliex l-isem
tip ta ', tip ta' arcanely jissuġġerixxi,

528
00:23:55,410 --> 00:23:57,940
huwa funzjoni li
gets karattru u għalhekk,

529
00:23:57,940 --> 00:24:00,690
x'hemm fundamentalment differenti
dwar dak li aħna qed tagħmel fil GetString

530
00:24:00,690 --> 00:24:03,110
hija aħna ma tkunx qed tużah
scanf bl-istess mod.

531
00:24:03,110 --> 00:24:07,550
Aħna biss creeping tul pass-pass
fuq x'ikun l-utent ikun ittajpjat fil,

532
00:24:07,550 --> 00:24:10,970
għaliex nistgħu dejjem jalloka wieħed
char, u għalhekk nistgħu dejjem sikur

533
00:24:10,970 --> 00:24:15,599
tħares lejn char wieħed fi żmien, u
l-magic jibda jiġri hawn.

534
00:24:15,599 --> 00:24:17,890
Jien ser iscroll biex
-nofs ta 'din il-funzjoni

535
00:24:17,890 --> 00:24:20,360
biss biex jintroduċi fil-qosor din il-funzjoni.

536
00:24:20,360 --> 00:24:22,670
Ħafna bħal hemm
funzjoni malloc, hemm

537
00:24:22,670 --> 00:24:27,740
funzjoni realloc fejn realloc
ihallik jirriallokaw blokki ta 'memorja

538
00:24:27,740 --> 00:24:29,570
u jagħmilha akbar jew iżgħar.

539
00:24:29,570 --> 00:24:33,060
Istorja sakemm qasir u ma
mewġa ta 'naħa tiegħi għal-lum,

540
00:24:33,060 --> 00:24:35,620
jafu li dak li GetString
qed tagħmel huwa huwa sort

541
00:24:35,620 --> 00:24:39,720
tal magically tkabbir jew
jiċkienu l buffer kif l-utent

542
00:24:39,720 --> 00:24:41,440
tipi fil string tiegħu jew tagħha.

543
00:24:41,440 --> 00:24:43,962
>> Mela jekk it-tipi utent ta '
string qasir, dan il-kodiċi

544
00:24:43,962 --> 00:24:45,920
biss talloka biżżejjed
memorja li jitwaħħal il-sekwenza.

545
00:24:45,920 --> 00:24:48,086
Jekk l-utent iżomm ittajpjar
kif I ma kien għal darb'oħra u darb'oħra

546
00:24:48,086 --> 00:24:50,330
u għal darb'oħra, ukoll, jekk il-
buffer inizjalment dan big

547
00:24:50,330 --> 00:24:53,310
u l-programm jirrealizza, li
stenna minuta, jien l-ispazju,

548
00:24:53,310 --> 00:24:55,410
li għaddej biex tirdoppja
id-daqs tal-buffer

549
00:24:55,410 --> 00:24:59,110
u mbagħad doppju tad-daqs tal-buffer
u l-kodiċi li ma l-irduppjar,

550
00:24:59,110 --> 00:25:03,170
jekk inħarsu lejn din here, huwa
biss dan għaqlija one-liner.

551
00:25:03,170 --> 00:25:06,830
Inti tista 'ma raw dan sintassi
qabel, imma jekk inti tgħidli star ugwali,

552
00:25:06,830 --> 00:25:10,470
dan huwa l-istess ħaġa bħat
qal drabi kapaċità 2.

553
00:25:10,470 --> 00:25:13,390
Allura hija biss iżomm irduppjar
il-kapaċità tal-buffer

554
00:25:13,390 --> 00:25:17,480
u mbagħad javżak realloc li tagħti
innifsu li l-memorja ħafna aktar.

555
00:25:17,480 --> 00:25:19,720
>> Issa, bħala twarrib, hemm
huma funzjonijiet oħra fil hawn

556
00:25:19,720 --> 00:25:23,680
li aħna mhux se tħares lejn xi dettall
minbarra li juru fil GetInt,

557
00:25:23,680 --> 00:25:26,150
nużaw GetString fil GetInt.

558
00:25:26,150 --> 00:25:28,192
Aħna tiċċekkja li mhuwiex
null, li, irtirar,

559
00:25:28,192 --> 00:25:30,400
huwa l-valur speċjali li
ifisser xi ħaġa li marret ħażin.

560
00:25:30,400 --> 00:25:31,233
Aħna tal-memorja.

561
00:25:31,233 --> 00:25:32,310
Aħjar tiċċekkja għal dan.

562
00:25:32,310 --> 00:25:33,710
U nerġgħu lura valur sentinella.

563
00:25:33,710 --> 00:25:37,850
Imma jien ser tiddifferixxi għall-kummenti dwar
għaliex u mbagħad nużaw dan ku ta scanf

564
00:25:37,850 --> 00:25:42,100
imsejħa sscanf u jirriżulta
li scanf sscanf, jew spag,

565
00:25:42,100 --> 00:25:45,310
ihallik tagħti ħarsa lejn il-linja li
l-utent ikun ittajpjat fi u tavżak

566
00:25:45,310 --> 00:25:49,610
janalizzah essenzjalment u dak jien
tagħmel hawnhekk huwa jien javżak sscanf,

567
00:25:49,610 --> 00:25:54,440
tanalizza ikun x'ikun l-utent għandu
ttajpjata u kun żgur% i,

568
00:25:54,440 --> 00:25:59,250
hemm huwa integer fiha, u aħna mhux se
jsibu rwieħhom illum eżattament għaliex hemm ukoll

569
00:25:59,250 --> 00:26:03,760
a% c hawn, iżda li fi ftit kliem jippermetti
us biex tiskopri jekk l-utent ikun ittajpjat

570
00:26:03,760 --> 00:26:06,050
xi ħaġa fittizji wara n-numru.

571
00:26:06,050 --> 00:26:11,766
Allura r-raġuni li GetInt u GetString
jgħidlek biex retry, retry, retry

572
00:26:11,766 --> 00:26:13,640
huwa minħabba kollha ta '
dan il-kodiċi konna bil-miktub,

573
00:26:13,640 --> 00:26:17,900
Huwa tip ta 'tħares lejn input-utent
fit-teħid ċert li huwa kompletament numerika

574
00:26:17,900 --> 00:26:21,700
jew huwa ta 'floating attwali
valur tal-punt jew bħalhom,

575
00:26:21,700 --> 00:26:24,233
jiddependi fuq liema valur
funzjoni inti qed tuża.

576
00:26:24,233 --> 00:26:25,060
>> Whew.

577
00:26:25,060 --> 00:26:25,710
KOLLOX SEW.

578
00:26:25,710 --> 00:26:27,592
Dan kien f'gidma
imma l-punt hawnhekk huwa

579
00:26:27,592 --> 00:26:29,550
li r-raġuni kellna
dawk ir-roti ta 'taħriġ dwar

580
00:26:29,550 --> 00:26:32,880
huwa minħabba fl-inqas livell,
hemm biss tant affarijiet li

581
00:26:32,880 --> 00:26:35,674
tista 'tmur ħażin li ridna
li preemptively jimmaniġġaw

582
00:26:35,674 --> 00:26:38,090
dawk l-affarijiet ċertament fil-
ġimgħat kmieni tal-klassi,

583
00:26:38,090 --> 00:26:42,230
iżda issa ma PSet erba 'u PSet ħames u
lil hinn se tara li huwa aktar unto

584
00:26:42,230 --> 00:26:45,570
inti imma wkoll int aktar kapaċi
biex jissolvew dawk tipi ta 'problemi

585
00:26:45,570 --> 00:26:47,180
yourself.

586
00:26:47,180 --> 00:26:51,770
Kwalunkwe mistoqsijiet dwar GetString jew GetInt?

587
00:26:51,770 --> 00:26:52,630
Yeah?

588
00:26:52,630 --> 00:26:55,130
>> UDJENZA: Għaliex kieku inti doppja
il-kapaċità tal-buffer

589
00:26:55,130 --> 00:26:57,630
aktar milli biss tiżdied
lilha mill-ammont eżatt?

590
00:26:57,630 --> 00:26:58,100
>> DAVID Malan: Tajba kwistjoni.

591
00:26:58,100 --> 00:27:00,474
Għaliex kieku aħna doppju tal-kapaċità
tal-buffer għall-kuntrarju

592
00:27:00,474 --> 00:27:02,800
għal ftit tiżdied it
billi xi valur kostanti?

593
00:27:02,800 --> 00:27:03,900
Kienet deċiżjoni disinn.

594
00:27:03,900 --> 00:27:08,590
Aħna biss iddeċieda li minħabba li hemm tendenza li
jkun ftit għaljin għaqli time li jistaqsu

595
00:27:08,590 --> 00:27:10,440
is-sistema operattiva
għall-memorja, aħna ma

596
00:27:10,440 --> 00:27:13,210
tixtieq li jispiċċaw jkollna fis
sitwazzjoni ta 'sekwenzi kbar

597
00:27:13,210 --> 00:27:14,960
li konna tistaqsi
l-OS ġdid u għal darb'oħra

598
00:27:14,960 --> 00:27:17,500
u għal darb'oħra u għal darb'oħra fl
f'suċċessjoni rapida għall-memorja.

599
00:27:17,500 --> 00:27:20,387
Allura aħna biss iddeċieda, xi ftit
arbitrarju iżda nisperaw raġonevolment,

600
00:27:20,387 --> 00:27:22,720
li, inti taf liema, ejja
nipprova nikseb l quddiem ta 'ruħna

601
00:27:22,720 --> 00:27:25,520
u biss iżommu irduppjar hekk li
aħna jimminimizzaw l-ammont ta 'drabi

602
00:27:25,520 --> 00:27:29,010
għandna sejħa malloc jew
realloc, iżda sentenza total

603
00:27:29,010 --> 00:27:31,820
sejħa fin-nuqqas li wieħed ikun jaf
liema utenti tista 'tixtieq li tip.

604
00:27:31,820 --> 00:27:33,600
Iż-żewġ modi jista 'jkun diskutibbli.

605
00:27:33,600 --> 00:27:35,430
Wieħed jista 'jargumenta tajba.

606
00:27:35,430 --> 00:27:39,240
>> Mela ejja tagħti ħarsa lejn koppja
ta 'effetti sekondarji oħra ta' memorja,

607
00:27:39,240 --> 00:27:41,610
affarijiet li jistgħu imorru ħażin
u għodod li inti tista

608
00:27:41,610 --> 00:27:43,880
jużaw biex jaqbdu dawn it-tipi ta 'żbalji.

609
00:27:43,880 --> 00:27:47,800
Jirriżulta lilkom kollha, anki jekk
check50 ma qallek kemm,

610
00:27:47,800 --> 00:27:50,050
ġew miktub Buggy
kodiċi peress ġimgħa,

611
00:27:50,050 --> 00:27:53,630
anki jekk it-testijiet kollha check50 huma
għadda, u anki jekk inti u TF tiegħek

612
00:27:53,630 --> 00:27:56,010
huma super kunfidenti li
kodiċi tiegħek taħdem kif maħsub.

613
00:27:56,010 --> 00:27:59,190
Kodiċi tiegħek ġie Buggy jew
difettuż li kollha inti,

614
00:27:59,190 --> 00:28:02,540
fl-użu tal-librerija CS50,
ġew jnixxu memorja.

615
00:28:02,540 --> 00:28:06,040
Inti kont qed tistaqsi s-sistema operattiva
għall-memorja fil-maġġoranza tal-programmi

616
00:28:06,040 --> 00:28:08,850
inti stajt bil-miktub, iżda inti stajt
fatt qatt ma taha lura.

617
00:28:08,850 --> 00:28:12,110
You ħadthom imsejħa GetString
u GetInt u GetFloat,

618
00:28:12,110 --> 00:28:15,270
iżda ma GetString, inti ħadthom
qatt imsejħa unGetString jew Agħti

619
00:28:15,270 --> 00:28:19,890
String Lura jew bħalhom, iżda Rajna
li GetString ma jalloka memorja

620
00:28:19,890 --> 00:28:22,810
permezz ta 'malloc jew ta' dan
realloc funzjoni, li huwa biss

621
00:28:22,810 --> 00:28:25,670
simili ħafna fl-ispirtu,
u għadhom, aħna kont qed

622
00:28:25,670 --> 00:28:28,629
titlob lill-sistema operattiva għall
memorja u l-memorja darb'oħra u għal darb'oħra

623
00:28:28,629 --> 00:28:29,670
iżda qatt ma jagħtu lura.

624
00:28:29,670 --> 00:28:33,550
>> Issa, bħala twarrib, jirriżulta li
meta programm quits, kollha tal-memorja

625
00:28:33,550 --> 00:28:34,870
hija awtomatikament meħlus.

626
00:28:34,870 --> 00:28:36,150
Allura huwa ma kienx jittrattaw enormi.

627
00:28:36,150 --> 00:28:38,590
Mhuwiex ser jiksru l-
IDE jew affarijiet jmajna,

628
00:28:38,590 --> 00:28:40,670
Imma meta programmi do
ġeneralment nixxija memorja

629
00:28:40,670 --> 00:28:42,170
u dawn qed taħdem għal żmien twil.

630
00:28:42,170 --> 00:28:45,640
Jekk inti stajt qatt dehru l-ftit stupid
bajja ballun fil Mac OS jew l-hourglass

631
00:28:45,640 --> 00:28:51,160
fuq Windows fejn huwa tip ta
jonqos jew il-ħsieb jew ħsieb

632
00:28:51,160 --> 00:28:53,770
jew biss verament jibda
li bil-mod għal jitkaxkru,

633
00:28:53,770 --> 00:28:56,960
possibbilment ħafna jista 'jkun
ir-riżultat ta 'tnixxija memorja.

634
00:28:56,960 --> 00:28:59,970
Il-programmaturi li kiteb
l-software inti qed tuża

635
00:28:59,970 --> 00:29:03,570
titlob lill-sistema operattiva għall-memorja
kull ftit minuti, kull siegħa.

636
00:29:03,570 --> 00:29:05,570
Imma jekk int taħdem l-
software, anki jekk huwa

637
00:29:05,570 --> 00:29:08,680
minimizzat fil-kompjuter tiegħek
għal sigħat jew ġranet fuq il-għan,

638
00:29:08,680 --> 00:29:11,980
inti tista 'tistaqsi għal aktar u aktar
memorja u qatt fil-fatt tużaha

639
00:29:11,980 --> 00:29:15,180
u għalhekk kodiċi tiegħek jista 'jkun, jew
programmi jista 'jiġi jnixxu memorja,

640
00:29:15,180 --> 00:29:18,350
u jekk tibda tnixxi memorja,
hemm memorja inqas għal programmi oħra,

641
00:29:18,350 --> 00:29:21,220
u l-effett huwa li
bil-mod kollox stabbiliti.

642
00:29:21,220 --> 00:29:23,600
>> Issa, dan huwa bil-wisq wieħed mill
l-programmi l-aktar atroċi

643
00:29:23,600 --> 00:29:26,350
ser ikollok opportunitajiet
jiddekorri fil CS50 sakemm

644
00:29:26,350 --> 00:29:31,650
bħala l-produzzjoni tagħha huwa saħansitra aktar esoteric minn
tal clang jew jagħmlu jew kwalunkwe tal-kmand

645
00:29:31,650 --> 00:29:35,930
programmi line konna run qabel imma
Thankfully, integrati fil-produzzjoni tagħha

646
00:29:35,930 --> 00:29:39,810
huwa xi tips utli super li
se jkun utli jew għall PSet erba

647
00:29:39,810 --> 00:29:41,510
jew ċertament PSet ħamsa.

648
00:29:41,510 --> 00:29:44,250
Allura valgrind hija għodda
li jistgħu jintużaw biex tfittex

649
00:29:44,250 --> 00:29:46,930
għat-tnixxija memorja fil-programm tiegħek.

650
00:29:46,930 --> 00:29:48,570
Huwa relattivament sempliċi biex imexxu.

651
00:29:48,570 --> 00:29:51,420
Inti tmexxi valgrind u mbagħad, anke
għalkemm huwa verbose ftit,

652
00:29:51,420 --> 00:29:54,440
sing check tnixxija sing
ugwali sħiħa, u mbagħad dot

653
00:29:54,440 --> 00:29:56,320
slash u l-isem tal-programm tiegħek.

654
00:29:56,320 --> 00:30:00,010
Allura valgrind mbagħad jimxu program tiegħek
u fl-aħħar nett tal-programm tiegħek

655
00:30:00,010 --> 00:30:02,240
running qabel quits u
jagħtik ieħor fil-pront,

656
00:30:02,240 --> 00:30:04,980
li għaddej biex tanalizza tiegħek
programm filwaqt li huwa kien għaddej

657
00:30:04,980 --> 00:30:07,740
u jgħidlek ma inti nixxija
kwalunkwe memorja u aħjar għadhom,

658
00:30:07,740 --> 00:30:10,610
ma inti touch memorja li
ma kienx jappartjeni lilek?

659
00:30:10,610 --> 00:30:13,700
Hija ma tistax qabda kollox, imma hija
pjuttost tajba fil-qbid aktar affarijiet.

660
00:30:13,700 --> 00:30:19,700
>> Allura hawnhekk eżempju ta 'tiegħi li run
dan il-programm, li tellgħu valgrind,

661
00:30:19,700 --> 00:30:21,470
fuq programm imsejjaħ
memorja, u jien ser

662
00:30:21,470 --> 00:30:24,730
li tenfasizza l-linji li huma
finalment ta 'interess għalina.

663
00:30:24,730 --> 00:30:27,690
Allura hemm anke aktar distrazzjonijiet
li stajt mħassra mill-slide.

664
00:30:27,690 --> 00:30:30,930
Imma ejja biss tara dak li dan
programm huwa kapaċi ta 'tgħidilna.

665
00:30:30,930 --> 00:30:34,800
Huwa kapaċi tgħidilna affarijiet
bħal tikteb invalidu d-daqs 4.

666
00:30:34,800 --> 00:30:38,020
Fi kliem ieħor, jekk inti touch memorja,
speċifikament 4 bytes ta 'memorja

667
00:30:38,020 --> 00:30:40,350
li m'għandekx ikollok,
valgrind jista 'jgħidlek li.

668
00:30:40,350 --> 00:30:41,660
Tikteb Invalid-daqs 4.

669
00:30:41,660 --> 00:30:43,640
Inti mimsus erba 'bytes
li m'għandekx ikollok.

670
00:30:43,640 --> 00:30:44,840
Fejn ma inti tagħmel dan?

671
00:30:44,840 --> 00:30:45,900
Dan huwa l-sbuħija.

672
00:30:45,900 --> 00:30:50,000
Linja c Memorja dot 21 huwa fejn inti
invitat up u hu għalhekk huwa utli.

673
00:30:50,000 --> 00:30:53,410
Ferm simili GDB, dan jista 'jgħin
punt inti fil-iżball attwali.

674
00:30:53,410 --> 00:30:57,170
>> Issa, dan wieħed huwa aktar ftit
verbose, jew saħansitra konfużi.

675
00:30:57,170 --> 00:31:01,307
40 bytes fil 1 blokki huma definittivament
mitlufa fir-rekord telf 1 ta '1.

676
00:31:01,307 --> 00:31:02,140
Xi tfisser?

677
00:31:02,140 --> 00:31:05,920
Ukoll, dan ifisser biss inti tlabt għal
40 bytes u int qatt ma taw lura.

678
00:31:05,920 --> 00:31:08,930
Inti imsejħa malloc jew inti imsejħa
GetString u s-sistema operattiva

679
00:31:08,930 --> 00:31:12,450
ħadt 40 bytes, imma int qatt ma
meħlusa jew rilaxxat li l-memorja,

680
00:31:12,450 --> 00:31:15,400
u li jkun ġust, aħna qatt ma stajt juru
kif għandek tagħti lura memorja.

681
00:31:15,400 --> 00:31:17,910
Jinstabx hemm super
funzjoni sempliċi imsejħa ħielsa.

682
00:31:17,910 --> 00:31:21,170
Jieħu argument wieħed, il-ħaġa
inti tixtieq li ħielsa jew jagħtu lura,

683
00:31:21,170 --> 00:31:23,430
iżda 40 bytes, apparentement,
f'dan il-programm

684
00:31:23,430 --> 00:31:27,300
intilfu fil-linja
20 ta 'memorja dot c.

685
00:31:27,300 --> 00:31:28,650
>> Mela ejja ara dan il-programm.

686
00:31:28,650 --> 00:31:31,020
Huwa super inutli.

687
00:31:31,020 --> 00:31:33,980
Hija turi biss
dan l-iżball partikolari.

688
00:31:33,980 --> 00:31:34,920
Mela ejja tagħti ħarsa.

689
00:31:34,920 --> 00:31:39,920
Hawnhekk huwa ewlenin u ewlenin, avviż, sejħiet
funzjoni msejħa f u mbagħad jirritornaha.

690
00:31:39,920 --> 00:31:41,550
Allura mhux kollha li interessanti.

691
00:31:41,550 --> 00:31:42,664
X'jagħmel f do?

692
00:31:42,664 --> 00:31:44,330
Avviż I ma jolqot bl prototip.

693
00:31:44,330 --> 00:31:46,520
I riedu jżommu l-kodiċi
minimi kemm jista 'jkun.

694
00:31:46,520 --> 00:31:49,530
So I tpoġġi f 'hawn fuq prinċipali u
li l-multa, ċertament,

695
00:31:49,530 --> 00:31:51,500
għal programmi qosra bħal dan.

696
00:31:51,500 --> 00:31:56,910
Allura f ma jerġax lura xejn u ma
M'għandekx tieħu xejn, iżda ma tagħmel dan.

697
00:31:56,910 --> 00:31:59,620
Tiddikjara, ħafna bħal
fl-eżempju Binky,

698
00:31:59,620 --> 00:32:02,682
a pointer imsejjaħ x li għaddej
biex jaħżnu l-indirizz ta 'int.

699
00:32:02,682 --> 00:32:03,890
Allura dak in-naħa tax-xellug.

700
00:32:03,890 --> 00:32:07,230
Bl-Ingliż, liema huwa l-
naħa tal-lemin tagħmel?

701
00:32:07,230 --> 00:32:09,770
Kulħadd?

702
00:32:09,770 --> 00:32:13,665
X'inhu dan tagħmel għalina?

703
00:32:13,665 --> 00:32:14,651
Yeah?

704
00:32:14,651 --> 00:32:16,623
>> UDJENZA: [inaudible]
darbiet id-daqs ta 'int

705
00:32:16,623 --> 00:32:19,175
li huwa 10 darbiet li [inaudible]

706
00:32:19,175 --> 00:32:20,800
DAVID Malan: Tajba u let me tqassar.

707
00:32:20,800 --> 00:32:25,480
Allura jalloka biżżejjed spazju għal 10 interi
jew 10, x'inhu l-daqs ta 'int,

708
00:32:25,480 --> 00:32:29,340
huwa l-erba 'bytes, hekk 10 darbiet 4 huwa
40, sabiex dik in-naħa tal-lemin li stajt

709
00:32:29,340 --> 00:32:33,930
enfasizzati huwa jagħti me 40 bytes u
jaħżnu l-indirizz ta 'l-ewwel byte

710
00:32:33,930 --> 00:32:34,940
fis x.

711
00:32:34,940 --> 00:32:38,380
U issa fl-aħħar, u hawn fejn
dan il-programm huwa Buggy, x'hemm

712
00:32:38,380 --> 00:32:41,540
ħażin bil-linja 21 ibbażata fuq li l-loġika?

713
00:32:41,540 --> 00:32:45,197

714
00:32:45,197 --> 00:32:46,280
X'hemm ħażin mal-linja 21?

715
00:32:46,280 --> 00:32:46,780
Yeah?

716
00:32:46,780 --> 00:32:49,550
UDJENZA: Inti ma tistax
Indiċi fis x [inaudible].

717
00:32:49,550 --> 00:32:50,300
DAVID Malan: Yeah.

718
00:32:50,300 --> 00:32:52,270
I m'għandhomx indiċi fi x bħal dik.

719
00:32:52,270 --> 00:32:53,850
Allura b'mod sintattiku, li OK.

720
00:32:53,850 --> 00:32:56,990
X'hemm sbieħ huwa, ferm simili inti
jista 'jikkura l-isem ta' firxa

721
00:32:56,990 --> 00:33:01,080
bħallikieku huwa pointer, b'mod simili
inti tista jittrattaw pointer bħallikieku huwa

722
00:33:01,080 --> 00:33:06,425
firxa, u so I tista sintattikament
ngħid xi ħaġa x parentesi, x parentesi i,

723
00:33:06,425 --> 00:33:07,800
iżda l-10 hija problematika.

724
00:33:07,800 --> 00:33:09,096
Għaliex?

725
00:33:09,096 --> 00:33:10,910
>> UDJENZA: Għaliex dan huwa mhux ġewwa.

726
00:33:10,910 --> 00:33:12,390
>> DAVID Malan: Mhuwiex
ġewwa li blokki ta 'memorja.

727
00:33:12,390 --> 00:33:15,306
X'hemm l-akbar valur I għandhom
tkun tqegħid f'dawk parentesi kwadri?

728
00:33:15,306 --> 00:33:16,870
9, 0 sa 9.

729
00:33:16,870 --> 00:33:18,160
Minħabba indiċjar żero.

730
00:33:18,160 --> 00:33:20,190
Allura 0 sa 9 tkun multa.

731
00:33:20,190 --> 00:33:23,960
Bracket 10 mhix tajba u
iżda, tfakkar għalkemm, kull darba

732
00:33:23,960 --> 00:33:27,017
I jidhru li jippruvaw jagħmlu CS50 IDE
tiġrifa billi tittajpja valuri fittizji,

733
00:33:27,017 --> 00:33:29,100
dan mhux dejjem jikkooperaw,
u fil-fatt, inti spiss

734
00:33:29,100 --> 00:33:31,460
jiksbu xxurtjati biss minħabba l-
sistema operattiva ma

735
00:33:31,460 --> 00:33:35,467
avviż li inti dejjem hekk ftit
jgħaddu xi blokki ta 'memorja,

736
00:33:35,467 --> 00:33:38,300
għaliex inti qagħdu fi ħdan teknikament
segment tiegħek, iżda aktar fuq li

737
00:33:38,300 --> 00:33:40,940
fi klassi sistemi operattivi,
u għalhekk xi ħaġa bħal din

738
00:33:40,940 --> 00:33:43,000
tista 'faċilment tmur jinstabux.

739
00:33:43,000 --> 00:33:48,120
Program tiegħek qatt se crash
b'mod konsistenti imma forsi darba awhile.

740
00:33:48,120 --> 00:33:50,610
>> U hekk ejja jippruvaw valgrind
fuq dan, u hawnhekk

741
00:33:50,610 --> 00:33:52,870
fejn aħna ser tingħata megħlub
mill-output mumentarjament.

742
00:33:52,870 --> 00:34:00,810
Sabiex tagħmel memorja nixxija valgrind check
ugwali memorja sħiħa dot slash.

743
00:34:00,810 --> 00:34:03,040
U hawnhekk għaliex I wegħda
dan jisbqu.

744
00:34:03,040 --> 00:34:05,700
Hawn dak valgrind, hawn hu dak
programmer, xi snin ago-

745
00:34:05,700 --> 00:34:08,469
iddeċieda li tkun idea tajba
għal ħruġ biex look like.

746
00:34:08,469 --> 00:34:09,750
Mela ejja jagħmlu sens ta 'dan.

747
00:34:09,750 --> 00:34:13,120
Allura-triq kollha fuq il-naħa tax-xellug
naħa għall-ebda raġuni tajba

748
00:34:13,120 --> 00:34:16,620
huwa l-ID proċess tal-programm
aħna biss run, l-identifikatur uniku

749
00:34:16,620 --> 00:34:18,030
għall-programm aħna biss dam.

750
00:34:18,030 --> 00:34:19,738
Aħna imħassar li mill
l-slide, iżda hemm

751
00:34:19,738 --> 00:34:22,190
xi informazzjoni utli hawn.

752
00:34:22,190 --> 00:34:24,684
>> Ejja iscroll sal-quċċata ħafna.

753
00:34:24,684 --> 00:34:25,600
Hawn fejn bdejna.

754
00:34:25,600 --> 00:34:27,040
Allura huwa mhux kollha li ħafna output.

755
00:34:27,040 --> 00:34:30,429
Hawn dak write invalidi
daqs 4 dwar linja 21.

756
00:34:30,429 --> 00:34:31,760
Well, dak li kien line 21?

757
00:34:31,760 --> 00:34:34,500
Linja 21 kien eżattament
dan u jagħmel sens

758
00:34:34,500 --> 00:34:37,290
li jien fil validament
miktub 4 bytes għaliex jien

759
00:34:37,290 --> 00:34:40,389
jippruvaw joħolqu dan numru sħiħ,
li jista 'jvarja,

760
00:34:40,389 --> 00:34:42,370
hija biss jiġri li jkun
żero, imma jien jippruvaw

761
00:34:42,370 --> 00:34:44,940
li tqiegħed lilha f'lok
li ma jappartjenix lili.

762
00:34:44,940 --> 00:34:50,900
Barra minn hekk, l hawn, 40 bytes f'wieħed
blokok huma definittivament mitlufa fir-rekord 1.

763
00:34:50,900 --> 00:34:56,500
Dak għax meta I call malloc
hawn, jien qatt ma attwalment ħielsa l-memorja.

764
00:34:56,500 --> 00:34:58,140
>> Allura kif nistgħu jiffissaw dan?

765
00:34:58,140 --> 00:35:02,970
Let me imorru quddiem u tkun ftit aktar sikuri
u jagħmlu 9 hemmhekk u let me hawn b'xejn x.

766
00:35:02,970 --> 00:35:04,820
Dan huwa l-funzjoni l-ġdida għal-lum.

767
00:35:04,820 --> 00:35:11,520
Jekk I issa terġa 'tagħmel memorja dot mmejla,
ejja jimxu valgrind fuq mill-ġdid,

768
00:35:11,520 --> 00:35:14,990
timmassimizza tieqa tiegħi u hit Ikteb.

769
00:35:14,990 --> 00:35:16,900
Issa, dan huwa tajjeb.

770
00:35:16,900 --> 00:35:19,590
Huma midfuna l-aħbar tajba
fil kollha ta 'dan l-output.

771
00:35:19,590 --> 00:35:20,810
Blokki kollha munzell kienu ħielsa.

772
00:35:20,810 --> 00:35:23,604
Aħna ser terga 'lura għal dak il-borġ
huwa, iżda l-ebda tnixxijiet huma possibbli.

773
00:35:23,604 --> 00:35:25,520
Allura dan huwa biss ieħor
għodda għall kit għodda tiegħek

774
00:35:25,520 --> 00:35:30,220
li magħhom inti tista 'tibda biex
isibu issa żbalji bħal dik.

775
00:35:30,220 --> 00:35:34,532
>> Imma ejja ara dak
aktar tista 'tmur ħażin hawn.

776
00:35:34,532 --> 00:35:38,890
Ejja tranżizzjoni issa biex
attwalment jsolvu problema.

777
00:35:38,890 --> 00:35:42,440
Bħala twarrib, jekk dan se jeħles
Ftit ftit ta 'konfużjoni jew ta' tensjoni,

778
00:35:42,440 --> 00:35:43,430
dan huwa issa umoristiċi.

779
00:35:43,430 --> 00:35:46,400

780
00:35:46,400 --> 00:35:46,900
Yeah.

781
00:35:46,900 --> 00:35:49,040
Li pjuttost tajba.

782
00:35:49,040 --> 00:35:50,890
Minħabba pointers huma
indirizzi u indirizzi

783
00:35:50,890 --> 00:35:53,098
huma ġeneralment permezz tal-konvenzjoni
miktub bil hexadeċimali.

784
00:35:53,098 --> 00:35:54,650
Ha, ha, dan huwa umoristiċi issa.

785
00:35:54,650 --> 00:35:58,390
Xorta, so ejja issa
attwalment issolvi problema.

786
00:35:58,390 --> 00:36:00,840
Dan kien super,
super-livell baxx s'issa,

787
00:36:00,840 --> 00:36:03,950
u aħna jistgħu attwalment jagħmlu utli
affarijiet ma dawn id-dettalji ta 'livell baxx.

788
00:36:03,950 --> 00:36:06,710
>> Allura aħna introdotti ftit ġimgħat
ilu l-kunċett ta 'firxa.

789
00:36:06,710 --> 00:36:09,177
Firxa kien sbieħ għaliex
huwa diffiċli biex tnaddaf kodiċi tagħna

790
00:36:09,177 --> 00:36:11,760
għaliex jekk ridna li jiktbu
programm ma 'studenti multipli

791
00:36:11,760 --> 00:36:15,270
jew ismijiet multipli u djar u
dorms u kulleġġi u kollha ta 'dak,

792
00:36:15,270 --> 00:36:19,430
nistgħu jaħżen kollox aktar
pulit ġewwa ta 'firxa.

793
00:36:19,430 --> 00:36:23,039
Iżda tipproponi tnaqqis wieħed
ta 'firxa s'issa.

794
00:36:23,039 --> 00:36:26,080
Anke jekk inti stajt ma sofra it yourself
fi programm, just istintivament,

795
00:36:26,080 --> 00:36:30,870
dak li huwa ħaġa ħażina
dwar firxa, forsi?

796
00:36:30,870 --> 00:36:32,337
Nisma xi murmurs.

797
00:36:32,337 --> 00:36:34,170
UDJENZA: Huwa diffiċli
Tibdilx id-daqs.

798
00:36:34,170 --> 00:36:36,128
DAVID Malan: Huwa diffiċli
Tibdilx id-daqs.

799
00:36:36,128 --> 00:36:38,660
Inti ma tistax tbiddel id-daqs
ta 'firxa, fil-fatt, per se

800
00:36:38,660 --> 00:36:43,040
fil C. Tista 'jalloka firxa ieħor,
jimxu kollox mill-qadima

801
00:36:43,040 --> 00:36:45,380
fil-ġdida, u issa
għandhom xi spazju żejjed,

802
00:36:45,380 --> 00:36:47,469
iżda mhuwiex simili għal
lingwa bħal Java jew Python

803
00:36:47,469 --> 00:36:49,760
jew kwalunkwe numru ta 'ieħor
lingwi li magħhom xi wħud minnkom

804
00:36:49,760 --> 00:36:52,070
jista 'jkun familjari fejn inti
tista 'sempliċement ikompli jżid affarijiet

805
00:36:52,070 --> 00:36:53,930
ad nauseam sa l-aħħar ta 'firxa.

806
00:36:53,930 --> 00:36:57,880
Meta inti għandek firxa ta '
daqs 6, li huwa d-daqs tagħha,

807
00:36:57,880 --> 00:37:01,970
u għalhekk ħafna bħall-idea ta 'qabel
li jkollhom buffer ta 'ċertu daqs,

808
00:37:01,970 --> 00:37:05,940
inti għandek raden barra tal-bieb
liema daqs tridu li tkun?

809
00:37:05,940 --> 00:37:07,880
Jekk inti raden kbira wisq,
int ħela ispazju.

810
00:37:07,880 --> 00:37:10,950
Jekk inti raden żgħir wisq, inti
ma jista 'jaħżen dik id-data, għall-inqas

811
00:37:10,950 --> 00:37:12,940
mingħajr ħafna aktar xogħol.

812
00:37:12,940 --> 00:37:18,180
>> Hekk illum, grazzi għall pointers, nistgħu
tibda legatura flimkien custom tagħna stess

813
00:37:18,180 --> 00:37:20,989
strutturi ta 'dejta, u b'mod
fatt, hawnhekk hija xi ħaġa

814
00:37:20,989 --> 00:37:23,030
li jistenna ftit aktar
cryptic ewwel daqqa t'għajn,

815
00:37:23,030 --> 00:37:26,440
iżda dan huwa dak li aħna ser sejħa marbuta
lista, u l-isem tip ta 'tiġbor fil-qosor tagħha

816
00:37:26,440 --> 00:37:26,940
it.

817
00:37:26,940 --> 00:37:29,550
Huwa lista ta 'numri, jew
F'dan il-każ, lista ta 'numri,

818
00:37:29,550 --> 00:37:33,480
iżda tista 'tkun lista ta' xejn, imma
huwa marbut flimkien permezz ta 'vleġeġ,

819
00:37:33,480 --> 00:37:36,380
u ħu raden
ma 'dak it-teknika

820
00:37:36,380 --> 00:37:38,310
aħna ser tkun tista
stitch flimkien,

821
00:37:38,310 --> 00:37:42,540
tip simili popcorn b'ħajta,
a marbut listi rettangoli hawn?

822
00:37:42,540 --> 00:37:43,936
Numri tagħha?

823
00:37:43,936 --> 00:37:45,560
X'hemm-karatteristika lingwa sottostanti?

824
00:37:45,560 --> 00:37:46,350
>> UDJENZA: A pointer.

825
00:37:46,350 --> 00:37:47,308
>> DAVID Malan: A pointer.

826
00:37:47,308 --> 00:37:51,700
Allura kull wieħed minn dawn vleġeġ hawn tirrappreżenta
pointer jew eżatt indirizz.

827
00:37:51,700 --> 00:37:54,590
Allura fi kliem ieħor, jekk irrid
li jaħżen lista ta 'numri,

828
00:37:54,590 --> 00:37:59,040
I tista 'mhux biss jaħżnu jekk irrid
l-abbiltà li jikbru u tiċkien

829
00:37:59,040 --> 00:38:00,990
istruttura tad-data tiegħi fil-firxa.

830
00:38:00,990 --> 00:38:03,000
So I jeħtieġ li jkollhom ftit
aktar sofistikazzjoni,

831
00:38:03,000 --> 00:38:05,720
iżda tinnota li din
stampa tip ta jissuġġerixxi

832
00:38:05,720 --> 00:38:08,650
li jekk inti stajt biss ltqajna ftit ħjut
konnessjoni kollox flimkien,

833
00:38:08,650 --> 00:38:13,100
probabbilment mhuwiex diffiċli li tagħmel spazju
bejn tnejn minn dawk rettangoli

834
00:38:13,100 --> 00:38:16,750
jew tnejn ta'dawk il-lymph, kif aħna ser tibda
titlob minnhom, titpoġġa fi node ġdid,

835
00:38:16,750 --> 00:38:19,547
u mbagħad ma 'xi thread ġdida, biss
foss-tliet lymph flimkien,

836
00:38:19,547 --> 00:38:22,880
l-ewwel waħda, l-aħħar waħda, u l-wieħed
li inti biss tiddaħħal fin-nofs.

837
00:38:22,880 --> 00:38:26,000
>> U fil-fatt lista marbuta,
b'differenza firxa, huwa dinamiku.

838
00:38:26,000 --> 00:38:27,840
Hija tista 'tikber u li tista
tiċkien u inti ma

839
00:38:27,840 --> 00:38:32,434
għandek tkun taf jew kura minn qabel kemm
data kemm int ser tkun ħażna,

840
00:38:32,434 --> 00:38:35,600
iżda jirriżulta irridu nkunu ftit
attenti dwar kif jimplimentaw din.

841
00:38:35,600 --> 00:38:39,070
Allura l-ewwel ejja tikkunsidra kif nimplimentaw
waħda minn dawn rettangoli ftit.

842
00:38:39,070 --> 00:38:40,690
Huwa faċli li jimplimentaw int.

843
00:38:40,690 --> 00:38:44,000
Inti biss jgħidu int nu mbagħad
ikollok 4 bytes għal int,

844
00:38:44,000 --> 00:38:49,089
imma kif nista 'nikseb xi int, sejħa hija n,
u mbagħad pointer, ejja sejħa hija li jmiss.

845
00:38:49,089 --> 00:38:50,880
Nistgħu sejħa dawn
affarijiet xejn irridu

846
00:38:50,880 --> 00:38:53,590
iżda għandu bżonn struttura data tad-dwana.

847
00:38:53,590 --> 00:38:54,257
Yeah?

848
00:38:54,257 --> 00:38:57,020
>> UDJENZA: ampersand [inaudible].

849
00:38:57,020 --> 00:39:00,940
>> DAVID Malan: Allura ampersand aħna se jużaw biex
jiksbu l-indirizz ta 'nodu potenzjalment.

850
00:39:00,940 --> 00:39:02,740
Iżda għandna bżonn ieħor
karatteristika ta 'C sabiex

851
00:39:02,740 --> 00:39:06,700
li tagħti me l-kapaċità li joħolqu
dan ir-rettangolu tad-dwana, dan il-użanza

852
00:39:06,700 --> 00:39:08,919
varjabbli jekk inti se, fil-memorja.

853
00:39:08,919 --> 00:39:09,710
UDJENZA: A Istituzzjonjijiet.

854
00:39:09,710 --> 00:39:10,626
DAVID Malan: A Istituzzjonjijiet.

855
00:39:10,626 --> 00:39:14,310
Recall mill-aħħar ġimgħa, daħħalna
Struct, dan il-keyword relattivament sempliċi

856
00:39:14,310 --> 00:39:16,254
li tikri us jagħmlu affarijiet bħal dan.

857
00:39:16,254 --> 00:39:18,420
C ma jiġu mal-data
istruttura imsejħa student.

858
00:39:18,420 --> 00:39:22,190
Jidħol ma int u float u char u
tali, iżda dan ma jaqax ma 'student,

859
00:39:22,190 --> 00:39:26,750
iżda nistgħu noħolqu tip ta 'data student,
struttura student, ma 'dan sintassi

860
00:39:26,750 --> 00:39:27,250
hawn.

861
00:39:27,250 --> 00:39:28,350
U tkun taf tara dan għal darb'oħra u darb'oħra.

862
00:39:28,350 --> 00:39:30,426
Allura ma joqogħdu jinkwetaw dwar
memorizing l-keywords,

863
00:39:30,426 --> 00:39:33,300
iżda l-keyword li l-importanti huwa
biss il-fatt li għidna Istituzzjonjijiet

864
00:39:33,300 --> 00:39:37,590
u allura aħna hija imsejħa student u ġewwa
tal-istudent kien l-isem u dar

865
00:39:37,590 --> 00:39:39,390
jew dorm jew bħalhom.

866
00:39:39,390 --> 00:39:41,980
>> U hekk issa llum, ejja tipproponi dan.

867
00:39:41,980 --> 00:39:45,240
Stajt miżjud ftit kliem, imma jekk irrid
biex jimplimentaw dan ir-rettangolu li l-

868
00:39:45,240 --> 00:39:48,440
ltqajna kemm int u
pointer, inti taf liema, jien

869
00:39:48,440 --> 00:39:51,540
ser tiddikjara Struct imsejjaħ node.

870
00:39:51,540 --> 00:39:55,630
Jien ukoll, ġewwa ta 'dan, ser tg
li node, dan ir-rettangolu, għandha int

871
00:39:55,630 --> 00:39:59,730
u aħna ser sejħa hija nu
hija għandha pointer li jmiss.

872
00:39:59,730 --> 00:40:02,540
U dan huwa xi ftit verbose,
imma jekk inti taħseb dwarha,

873
00:40:02,540 --> 00:40:07,300
l-vleġeġ li kienu fl-istampa
mument ilu huma ta 'liema tip ta' dejta?

874
00:40:07,300 --> 00:40:12,330
Jekk dawn il-vleġeġ qiegħda tipponta
liema tip ta 'struttura data?

875
00:40:12,330 --> 00:40:14,332
Huwa mhux biss tipponta lejn int per se.

876
00:40:14,332 --> 00:40:16,165
Huwa tipponta lejn il-
ħaġa rettangolari sħiħa

877
00:40:16,165 --> 00:40:18,720
u li ħaġa rettangolari,
għidna, huwa msejjaħ node.

878
00:40:18,720 --> 00:40:21,720
U hekk aħna tip ta 'għandekx
recursively jiddefinixxu tali dan

879
00:40:21,720 --> 00:40:26,270
li node, aħna għandu ngħidu,
se jkun fiha int imsejħa n

880
00:40:26,270 --> 00:40:31,070
u pointer imsejjaħ jmiss u l-
tip ta 'struttura data li għaliha

881
00:40:31,070 --> 00:40:35,770
li punti ta pointer hija apparentement
se tkun node Struct.

882
00:40:35,770 --> 00:40:41,550
>> Allura dan huwa annoyingly verbose
u biss sabiex ikunu pedantic,

883
00:40:41,550 --> 00:40:44,100
r-raġuni għaliex ma nistgħux
biss jgħidu dan, li franchement

884
00:40:44,100 --> 00:40:46,860
jistenna ħafna aktar leġġibbli,
huwa minħabba irtirar li C taqra

885
00:40:46,860 --> 00:40:48,710
affarijiet fuq għal isfel, xellug għal-lemin.

886
00:40:48,710 --> 00:40:54,120
Mhuwiex sakemm aħna jiksbu l-virgola
li l-node keyword fil-fatt teżisti.

887
00:40:54,120 --> 00:40:57,980
Mela jekk irridu li jkollna dan it-tip ta '
referenza ċiklika ġewwa tad-data

888
00:40:57,980 --> 00:41:02,120
istruttura, għandna nagħmlu dan, fejn
ngħidu node Struct fil-quċċata, li

889
00:41:02,120 --> 00:41:06,770
tagħtina mod itwal ta 'jiddeskrivi dan
ħaġa, allura ġewwa ngħidu node Struct,

890
00:41:06,770 --> 00:41:09,560
u mbagħad fl-aħħar linja
ngħidu, id-dritt, C, mill-mod,

891
00:41:09,560 --> 00:41:12,060
biss sejħa dan kkritikat kollu
ħaġa node u stop

892
00:41:12,060 --> 00:41:14,360
użu tal-Struct keyword għal kollox.

893
00:41:14,360 --> 00:41:18,030
Allura dan huwa biss tip ta 'sintattiku
trick li finalment tikri us joħolqu

894
00:41:18,030 --> 00:41:21,370
xi ħaġa li jidher eżattament bħal dan.

895
00:41:21,370 --> 00:41:25,010
>> Mela jekk nassumu issa nistgħu
jimplimentaw dan ħaġa fis-C,

896
00:41:25,010 --> 00:41:28,040
kif do we attwalment
tibda jaqsmu dan?

897
00:41:28,040 --> 00:41:32,360
Ukoll, fil-fatt, kollha għandna tagħmel hu
jtenni mix-xellug għal-lemin u biss

898
00:41:32,360 --> 00:41:35,960
tip ta 'daħħal lymph nodes jew iħassar
jew tfittxija għal affarijiet fejn irridu,

899
00:41:35,960 --> 00:41:39,560
iżda biex isir dan, ejja imorru quddiem u jagħmlu
affarijiet ftit aktar reali għaliex dan

900
00:41:39,560 --> 00:41:42,560
kien super-livell baxx s'issa.

901
00:41:42,560 --> 00:41:45,700
Kieku xi ħadd litteralment tixtieq li tkun l-ewwel?

902
00:41:45,700 --> 00:41:46,200
KOLLOX SEW.

903
00:41:46,200 --> 00:41:47,092
Come fuq up.

904
00:41:47,092 --> 00:41:47,800
X'hemm isem tiegħek?

905
00:41:47,800 --> 00:41:48,499
>> DAVID: David.

906
00:41:48,499 --> 00:41:49,290
DAVID Malan: David.

907
00:41:49,290 --> 00:41:49,998
Għandi pjaċir.

908
00:41:49,998 --> 00:41:50,960
Me wisq.

909
00:41:50,960 --> 00:41:52,450
Kull dritt.

910
00:41:52,450 --> 00:41:53,990
U għandna bżonn numru 9.

911
00:41:53,990 --> 00:41:55,240
Mhux tajbin daqs l-ewwel, forsi.

912
00:41:55,240 --> 00:41:56,430
OK, numru 9.

913
00:41:56,430 --> 00:41:59,667
A numru 17, jekk jogħġbok.

914
00:41:59,667 --> 00:42:01,000
Let me jmorru lura ftit farther.

915
00:42:01,000 --> 00:42:03,980
Numru 22, jekk jogħġbok, u
kif madwar farther lura

916
00:42:03,980 --> 00:42:06,344
jekk I tista 'tara l-ebda idejn
ma 'l-dawl jew l-ebda.

917
00:42:06,344 --> 00:42:08,010
Xi ħadd l-jiġu volontarju hemm dritt.

918
00:42:08,010 --> 00:42:08,968
Do inti tixtieq li toħroġ?

919
00:42:08,968 --> 00:42:10,450
Driegħ tiegħek sfurzat jogħla.

920
00:42:10,450 --> 00:42:12,340
OK, 17.

921
00:42:12,340 --> 00:42:13,690
22.

922
00:42:13,690 --> 00:42:15,120
26 huwa jinżlu.

923
00:42:15,120 --> 00:42:18,450
Would xi ħadd ieħor simili li
forcefully-- Come on up.

924
00:42:18,450 --> 00:42:21,030
Voluntier attwali.

925
00:42:21,030 --> 00:42:23,330
>> Allura malajr ħafna, jekk
inti guys tista 'tirranġa

926
00:42:23,330 --> 00:42:26,550
yourselves bħad
il-lymph fuq l-iskrin.

927
00:42:26,550 --> 00:42:27,510
Grazzi.

928
00:42:27,510 --> 00:42:29,234
U tkun taf tkun 26.

929
00:42:29,234 --> 00:42:30,650
Introduzzjonijiet kollha dritt u ta 'malajr.

930
00:42:30,650 --> 00:42:32,139
Hekk jien David u inti wkoll?

931
00:42:32,139 --> 00:42:32,680
DAVID: David.

932
00:42:32,680 --> 00:42:33,721
DAVID Malan: U int?

933
00:42:33,721 --> 00:42:34,229
Jake: Jake.

934
00:42:34,229 --> 00:42:34,729
SUE: Sue.

935
00:42:34,729 --> 00:42:35,229
ALEX: Alex.

936
00:42:35,229 --> 00:42:36,475
RAPHAEL: Raphael.

937
00:42:36,475 --> 00:42:37,100
TAYLOR: Taylor.

938
00:42:37,100 --> 00:42:37,466
DAVID Malan: Taylor.

939
00:42:37,466 --> 00:42:37,590
Eċċellenti.

940
00:42:37,590 --> 00:42:39,810
Allura dawn huma voluntiera tagħna
għal-lum u jimxi 'l quddiem

941
00:42:39,810 --> 00:42:43,090
u l-bidla ftit il-mod,
u biss jimxi 'l quddiem u jżomm

942
00:42:43,090 --> 00:42:47,024
azjenda numri tiegħek kif int jew tiegħek
ewwel sinjal u l-użu tax-xellug tiegħek,

943
00:42:47,024 --> 00:42:48,940
imorru quddiem u biss jimplimentaw
dawn vleġeġ, biss

944
00:42:48,940 --> 00:42:51,360
sabiex naħa tax-xellug tiegħek huwa litteralment
tipponta lejn kwalunkwe inti għandu punt

945
00:42:51,360 --> 00:42:54,610
lejn, u tagħti lilek innifsek xi kamra b'tali mod li
nistgħu viżwalment tara idejk attwalment

946
00:42:54,610 --> 00:42:58,120
tipponta, u inti tista 'biss il-punt
tip ta 'mill-art huwa multa.

947
00:42:58,120 --> 00:43:03,040
>> Allura hawnhekk għandna lista marbuta ta 'wieħed,
tnejn, tlieta, erba ', ħames lymph inizjalment,

948
00:43:03,040 --> 00:43:05,860
u avviż għandna dan speċjali
pointer fil-bidu li l-

949
00:43:05,860 --> 00:43:09,770
ċavetta għaliex għandna biex iżommu kont
tal-lista tul kollu b'xi.

950
00:43:09,770 --> 00:43:13,590
Dawn guys, anki jekk dawn qed xellug
għal-lemin, lura lura fil-memorja,

951
00:43:13,590 --> 00:43:15,950
huma jkunu effettivament jistgħu jkunu kullimkien
fil-memorja tal-kompjuter.

952
00:43:15,950 --> 00:43:18,240
Allura dawn guys tista 'tkun
wieqfa kullimkien fuq l-istadju

953
00:43:18,240 --> 00:43:20,960
u li l-multa, sakemm dawn qed
fatt li tipponta lejn xulxin,

954
00:43:20,960 --> 00:43:22,770
iżda li żżomm affarijiet
nadif u sempliċi, aħna ser

955
00:43:22,770 --> 00:43:25,728
biss tiġbed minnhom xellug għal-lemin simili
dan, imma jista 'jkun hemm lakuni kbar

956
00:43:25,728 --> 00:43:26,790
bejniethom ta'dawk il-lymph.

957
00:43:26,790 --> 00:43:30,710
>> Issa, jekk irrid li attwalment daħħal xi
valur il-ġdid, ejja imorru quddiem u tagħmel dan.

958
00:43:30,710 --> 00:43:33,720
Għandna l-opportunità issa
li jagħżlu node ieħor.

959
00:43:33,720 --> 00:43:39,820
Say ejja tibda bl mallocing 55.

960
00:43:39,820 --> 00:43:41,320
Would xi ħadd f'moħħu jkunu malloc?

961
00:43:41,320 --> 00:43:42,280
OK, jaqgħu fuq up.

962
00:43:42,280 --> 00:43:42,992
X'hemm isem tiegħek?

963
00:43:42,992 --> 00:43:43,700
RAINBOW: Rainbow.

964
00:43:43,700 --> 00:43:44,050
DAVID Malan: Rainbow?

965
00:43:44,050 --> 00:43:44,810
Kull dritt.

966
00:43:44,810 --> 00:43:46,600
Malloc Rainbow.

967
00:43:46,600 --> 00:43:47,450
Come fuq up.

968
00:43:47,450 --> 00:43:51,610
Allura issa għandna nistaqsu lilna nfusna
algorithmically fejn nistgħu npoġġu 55.

969
00:43:51,610 --> 00:43:53,610
Allura lkoll nafu,
ovvjament, fejn hi probabbilment

970
00:43:53,610 --> 00:43:55,401
tappartjeni jekk aħna qed tipprova
biex iżommu din magħżula

971
00:43:55,401 --> 00:43:58,299
u jekk inti guys tista 'tieħu waħda
pass lura hekk aħna ma jaqgħux off

972
00:43:58,299 --> 00:43:59,590
l-istadju, li tkun kbira.

973
00:43:59,590 --> 00:44:01,420
Allura fil-fatt, Rainbow,
tibda minn hawn miegħi,

974
00:44:01,420 --> 00:44:04,200
għaliex aħna bħala l-kompjuter issa jista
tara biss varjabbli waħda kull darba.

975
00:44:04,200 --> 00:44:05,190
Mela jekk dan huwa l-ewwel node.

976
00:44:05,190 --> 00:44:07,160
Avviż huwa ma node,
hu biss pointer,

977
00:44:07,160 --> 00:44:10,270
u hu għalhekk li hu mfassal biex ikun
biss id-daqs ta 'pointer, mhux

978
00:44:10,270 --> 00:44:11,780
wieħed minn dawk rettangoli sħiħa.

979
00:44:11,780 --> 00:44:16,650
Allura aħna qed tmur biex jiċċekkjaw f'kull
iterazzjoni hija 55 inqas minn 9?

980
00:44:16,650 --> 00:44:17,150
No

981
00:44:17,150 --> 00:44:19,060
Hija 55 inqas minn 17?

982
00:44:19,060 --> 00:44:19,720
No

983
00:44:19,720 --> 00:44:20,800
Inqas minn 22?

984
00:44:20,800 --> 00:44:22,020
Inqas minn 26?

985
00:44:22,020 --> 00:44:23,390
Inqas minn 34?

986
00:44:23,390 --> 00:44:25,890
U hekk issa, ovvjament
Rainbow jappartjeni fl-aħħar.

987
00:44:25,890 --> 00:44:27,270
Allura biex tkun ċara, u liema
kien l-isem tiegħek, Taylor?

988
00:44:27,270 --> 00:44:27,895
>> TAYLOR: Taylor.

989
00:44:27,895 --> 00:44:32,510
DAVID Malan: Allura fost l Taylor
naħa tax-xellug u l-idejn Rainbow hawn,

990
00:44:32,510 --> 00:44:38,324
li idejn jeħtieġ li jiġi lejn dak fil
tordna li daħħal 55 fis din il-lista?

991
00:44:38,324 --> 00:44:39,240
What do we bżonn tagħmel?

992
00:44:39,240 --> 00:44:39,700
Yeah?

993
00:44:39,700 --> 00:44:41,140
>> UDJENZA: idejn Taylor
jeħtieġ li jiġi xellug.

994
00:44:41,140 --> 00:44:41,680
>> DAVID Malan: Eżattament.

995
00:44:41,680 --> 00:44:43,800
Allura ddaħħal node
fit-tarf tal-lista

996
00:44:43,800 --> 00:44:47,140
huwa pjuttost sempliċi għaliex Taylor biss
għandu punt, minflok fil-art

997
00:44:47,140 --> 00:44:49,640
jew aħna ser sejħa hija nulla,
null huwa tip tan-nuqqas

998
00:44:49,640 --> 00:44:51,640
ta 'pointer jew speċjali
żero pointer, int

999
00:44:51,640 --> 00:44:53,740
jmorru għall-punt ma xellug tiegħek
idejn fil Rainbow u mbagħad Rainbow,

1000
00:44:53,740 --> 00:44:55,910
Fejn xellug tiegħek
naħa probabbilment punt?

1001
00:44:55,910 --> 00:44:56,570
Down.

1002
00:44:56,570 --> 00:45:00,140
Mhuwiex tajjeb jekk naħa tagħha huwa tip
tal tipponta off hawn jew tip ta 'kwalunkwe

1003
00:45:00,140 --> 00:45:00,640
li mod.

1004
00:45:00,640 --> 00:45:02,407
Li tkun ikkunsidrata
valur żibel,

1005
00:45:02,407 --> 00:45:04,240
imma jekk hi punti li
xi valur magħruf, aħna ser

1006
00:45:04,240 --> 00:45:07,360
sejħa hija żero jew null, li OK
għaliex għandna tul f'dan

1007
00:45:07,360 --> 00:45:09,390
u nafu l-lista issa hija kompluta.

1008
00:45:09,390 --> 00:45:11,550
>> Allura x'hemm ieħor
każ relattivament sempliċi?

1009
00:45:11,550 --> 00:45:13,125
Nistgħu malloc 5?

1010
00:45:13,125 --> 00:45:14,010
Come fuq up.

1011
00:45:14,010 --> 00:45:14,782
X'hemm isem tiegħek?

1012
00:45:14,782 --> 00:45:15,490
Tiffany: Tiffany.

1013
00:45:15,490 --> 00:45:16,000
DAVID Malan: Im sorry?

1014
00:45:16,000 --> 00:45:16,470
Tiffany: Tiffany.

1015
00:45:16,470 --> 00:45:16,880
DAVID Malan: Tiffany.

1016
00:45:16,880 --> 00:45:17,110
Kull dritt.

1017
00:45:17,110 --> 00:45:19,071
Tiffany ġie malloced
mal-valur 5.

1018
00:45:19,071 --> 00:45:19,570
Come fuq up.

1019
00:45:19,570 --> 00:45:23,820
Dan wieħed relattivament faċli wisq, iżda
ejja jikkunsidraw ordni ta 'operazzjonijiet issa.

1020
00:45:23,820 --> 00:45:25,820
Kien pjuttost faċli
mal Taylor fl-aħħar.

1021
00:45:25,820 --> 00:45:30,302
Numru 5 huwa naturalment anqas minn 9,
u hekk aħna David, għandna Tiffany,

1022
00:45:30,302 --> 00:45:31,260
u dak li kien l-isem tiegħek?

1023
00:45:31,260 --> 00:45:31,680
>> Jake: Jake.

1024
00:45:31,680 --> 00:45:32,470
>> DAVID Malan: Jake.

1025
00:45:32,470 --> 00:45:34,300
Tiffany, Jake, u David.

1026
00:45:34,300 --> 00:45:36,580
Li sekondaman għandhom ikunu aġġornati ewwel?

1027
00:45:36,580 --> 00:45:39,260

1028
00:45:39,260 --> 00:45:40,590
What do inti tixtieq li tagħmel hawn?

1029
00:45:40,590 --> 00:45:45,244
Hemm modi possibbli koppja, iżda
hemm ukoll modi aktar ħżiena wieħed jew.

1030
00:45:45,244 --> 00:45:46,620
>> UDJENZA: Tibda bl leftmost.

1031
00:45:46,620 --> 00:45:47,800
>> DAVID Malan: Tibda bil-leftmost.

1032
00:45:47,800 --> 00:45:49,008
Min hu l-leftmost hawn allura?

1033
00:45:49,008 --> 00:45:49,700
UDJENZA: L-ewwel.

1034
00:45:49,700 --> 00:45:50,366
>> DAVID Malan: OK.

1035
00:45:50,366 --> 00:45:53,781
Allura tibda bl-ewwel u fejn taħseb
tixtieq li taġġorna l-idejn David li tkun?

1036
00:45:53,781 --> 00:45:54,780
UDJENZA: Lejn l-5.

1037
00:45:54,780 --> 00:45:55,446
DAVID Malan: OK.

1038
00:45:55,446 --> 00:45:59,026
Allura David, punt ħamsa
jew Tiffany hawn, u issa?

1039
00:45:59,026 --> 00:46:01,072
>> UDJENZA: Tiffany juri l-9?

1040
00:46:01,072 --> 00:46:04,030
DAVID Malan: Perfect, ħlief l Binky
kap biss tip ta 'apostrofu, right?

1041
00:46:04,030 --> 00:46:06,820
Minħabba x'hemm ħażin ma
din l-istampa litteralment?

1042
00:46:06,820 --> 00:46:08,070
UDJENZA: Xejn hija li tipponta.

1043
00:46:08,070 --> 00:46:09,945
DAVID Malan: Xejn huwa
tipponta lejn Jake issa.

1044
00:46:09,945 --> 00:46:13,360
Imxejna litteralment orfni 9
u 17, u konna litteralment

1045
00:46:13,360 --> 00:46:18,450
nixxew kollha ta 'dan il-memorja, għaliex mill
aġġornament naħa David ewwel, li l-

1046
00:46:18,450 --> 00:46:21,660
multa sa fejn huwa korrett
tipponta lejn Tiffany issa,

1047
00:46:21,660 --> 00:46:25,410
imma jekk l-ebda wieħed kellu l-
previżjoni għall-punt fil Jake,

1048
00:46:25,410 --> 00:46:27,490
allura aħna tilfu il
totalità ta 'dik il-lista.

1049
00:46:27,490 --> 00:46:28,200
Mela ejja jħoll.

1050
00:46:28,200 --> 00:46:30,950
Allura li kienet ħaġa tajba li
vjaġġ fuq imma ejja jikkoreġu issa.

1051
00:46:30,950 --> 00:46:33,624
X'għandi nagħmlu ewwel minflok?

1052
00:46:33,624 --> 00:46:34,124
Yeah?

1053
00:46:34,124 --> 00:46:35,791
>> UDJENZA: Tiffany għandu jindika fil-9?

1054
00:46:35,791 --> 00:46:37,582
DAVID Malan: I ma tistax
nikseb li qrib lilek.

1055
00:46:37,582 --> 00:46:38,720
Min għandu punt fil-9?

1056
00:46:38,720 --> 00:46:39,220
>> UDJENZA: Tiffany.

1057
00:46:39,220 --> 00:46:39,390
>> DAVID Malan: Kull dritt.

1058
00:46:39,390 --> 00:46:41,200
Allura Tiffany għandu l-ewwel punt fuq l-9.

1059
00:46:41,200 --> 00:46:43,550
Allura Tiffany għandhom jieħdu
fuq valur identiku

1060
00:46:43,550 --> 00:46:45,820
li David, li tidher
żejda għal mument,

1061
00:46:45,820 --> 00:46:48,820
iżda li l-multa għaliex issa, it-tieni
pass, nistgħu taġġorna naħa David

1062
00:46:48,820 --> 00:46:52,680
punt fuq Tiffany, u mbagħad jekk
aħna biss tip ta 'teknoloġiji nodfa affarijiet up

1063
00:46:52,680 --> 00:46:55,740
bħallikieku dan huwa tip ta 'rebbiegħa simili,
issa li l-inserzjoni korretta.

1064
00:46:55,740 --> 00:46:56,700
Allura eċċellenti.

1065
00:46:56,700 --> 00:46:57,970
Allura issa aħna qed kważi hemm.

1066
00:46:57,970 --> 00:47:01,075
Ejja jdaħħal waħda finali
valur bħall-valur 20.

1067
00:47:01,075 --> 00:47:03,010
Jekk nistgħu malloc voluntier finali wieħed?

1068
00:47:03,010 --> 00:47:04,140
Come fuq up.

1069
00:47:04,140 --> 00:47:06,224
Allura dan wieħed l-ftit aktar delikata.

1070
00:47:06,224 --> 00:47:08,390
Imma verament, il-kodiċi aħna qed
miktub, għalkemm verbalment,

1071
00:47:08,390 --> 00:47:10,610
huwa biss simili li jkollhom mazz
tal jekk il-kundizzjonijiet issa, id-dritt?

1072
00:47:10,610 --> 00:47:12,318
Kellna kundizzjoni
verifika jekk ikun jappartjeni

1073
00:47:12,318 --> 00:47:13,840
fl-aħħar, forsi l-bidu.

1074
00:47:13,840 --> 00:47:15,940
Għandna bżonn xi tip ta 'loop biex
isibu l-post fin-nofs.

1075
00:47:15,940 --> 00:47:17,400
Mela ejja tagħmel dan ma 'dak l-isem tiegħek?

1076
00:47:17,400 --> 00:47:17,700
>> ERIC: Eric.

1077
00:47:17,700 --> 00:47:18,340
>> DAVID Malan: Eric?

1078
00:47:18,340 --> 00:47:18,660
Eric.

1079
00:47:18,660 --> 00:47:19,368
Għandi pjaċir.

1080
00:47:19,368 --> 00:47:20,490
Allura aħna għandna 20.

1081
00:47:20,490 --> 00:47:21,220
Inqas minn ħamsa?

1082
00:47:21,220 --> 00:47:21,530
No

1083
00:47:21,530 --> 00:47:22,160
Inqas minn disa?

1084
00:47:22,160 --> 00:47:22,410
No

1085
00:47:22,410 --> 00:47:23,050
Inqas minn 17?

1086
00:47:23,050 --> 00:47:23,550
No

1087
00:47:23,550 --> 00:47:23,740
KOLLOX SEW.

1088
00:47:23,740 --> 00:47:25,701
Huwa jappartjeni hawn u
ismijiet tiegħek mill-ġdid huma?

1089
00:47:25,701 --> 00:47:26,200
SUE: Sue.

1090
00:47:26,200 --> 00:47:26,880
DAVID Malan: Sue.

1091
00:47:26,880 --> 00:47:27,379
ALEX: Alex.

1092
00:47:27,379 --> 00:47:28,790
DAVID Malan: Sue, Alex, u?

1093
00:47:28,790 --> 00:47:29,290
ERIC: Eric.

1094
00:47:29,290 --> 00:47:30,120
DAVID Malan: Eric.

1095
00:47:30,120 --> 00:47:32,140
Li f'idejha bżonn tikseb aġġornati ewwel?

1096
00:47:32,140 --> 00:47:32,930
>> UDJENZA: Eric.

1097
00:47:32,930 --> 00:47:33,429
KOLLOX SEW.

1098
00:47:33,429 --> 00:47:35,200
Allura s Eric għandu jiġi lejn fejn?

1099
00:47:35,200 --> 00:47:35,930
Fil-22.

1100
00:47:35,930 --> 00:47:36,430
Tajba.

1101
00:47:36,430 --> 00:47:38,180
U issa xi jmiss?

1102
00:47:38,180 --> 00:47:40,800
Sue jista imbagħad il-punt fuq Eric
u issa, jekk inti guys biss

1103
00:47:40,800 --> 00:47:44,077
tagħmel xi kamra, li huwa multa
viżwalment, issa aħna ghamilt l-inserzjoni.

1104
00:47:44,077 --> 00:47:47,160
Mela ejja issa jeżamina xi kwistjoni, iżda
nirringrazzjak tant għall-voluntiera tagħna.

1105
00:47:47,160 --> 00:47:48,090
Isir ħafna tajjeb.

1106
00:47:48,090 --> 00:47:50,831
Inti tista 'żżomm dawn, jekk inti tixtieq.

1107
00:47:50,831 --> 00:47:54,140
U aħna għandna rigal firda sabiħ jekk
youd kull nieħu ballun stress.

1108
00:47:54,140 --> 00:47:56,030
Let me biss tgħaddi din isfel.

1109
00:47:56,030 --> 00:47:58,430
Allura x'inhi l-takeaway ta 'dan?

1110
00:47:58,430 --> 00:48:02,430
Dan jidher li aqwa
sakemm għandna issa

1111
00:48:02,430 --> 00:48:06,360
introduċiet alternattiva għall-
firxa li mhix daqshekk limitata

1112
00:48:06,360 --> 00:48:07,780
għal firxa ta 'ċertu daqs fiss.

1113
00:48:07,780 --> 00:48:09,380
Huma jistgħu jikbru b'mod dinamiku.

1114
00:48:09,380 --> 00:48:13,220
>> Iżda ferm simili Rajna fil-ġimgħat
passat, aħna qatt tikseb xejn b'xejn,

1115
00:48:13,220 --> 00:48:15,740
bħal żgur hemm kompromess hawn.

1116
00:48:15,740 --> 00:48:18,890
Allura ma 'rasu ta' marbut
lista, hija din dinamiżmu?

1117
00:48:18,890 --> 00:48:21,590
Din il-ħila biex jikbru u franchement,
aħna seta 'jsir ħassar

1118
00:48:21,590 --> 00:48:23,570
u aħna tista 'tiċkien kif meħtieġ.

1119
00:48:23,570 --> 00:48:24,710
Liema prezz aħna tħallas?

1120
00:48:24,710 --> 00:48:28,510

1121
00:48:28,510 --> 00:48:30,340
Darbtejn daqs ispazju, l-ewwel nett.

1122
00:48:30,340 --> 00:48:34,010
Jekk inti tħares lejn l-istampa, m'għadhiex
am I ħażna lista tan-numri interi.

1123
00:48:34,010 --> 00:48:36,740
Jien ħażna lista ta
interi plus pointers.

1124
00:48:36,740 --> 00:48:38,240
Hekk jien irduppjar tal-ammont ta 'spazju.

1125
00:48:38,240 --> 00:48:40,740
Issa, forsi li mhux tali
a big deal 4 bytes, 8 bytes,

1126
00:48:40,740 --> 00:48:43,160
iżda tista 'ċertament żid
up għal settijiet ta 'data kbar.

1127
00:48:43,160 --> 00:48:45,570
X'hemm tnaqqis ieħor?

1128
00:48:45,570 --> 00:48:46,070
Yeah?

1129
00:48:46,070 --> 00:48:48,010
>> UDJENZA: Irridu
travers minnhom wieħed mill-wieħed.

1130
00:48:48,010 --> 00:48:48,760
DAVID Malan: Yeah.

1131
00:48:48,760 --> 00:48:50,260
Irridu travers magħhom wieħed mill-wieħed.

1132
00:48:50,260 --> 00:48:53,860
Inti taf liema, aħna taw up dan super
Karatteristika konvenjenti ta 'faxxa kwadru

1133
00:48:53,860 --> 00:48:57,240
notazzjoni, aktar sew
magħrufa bħala t'aċċess bl-addoċċ,

1134
00:48:57,240 --> 00:48:59,280
fejn nistgħu biss jaqbżu
ma 'element individwali

1135
00:48:59,280 --> 00:49:01,470
imma issa jekk I xorta kellhom
voluntiera tiegħi hawn,

1136
00:49:01,470 --> 00:49:04,660
jekk jien ridt li jsibu l-
numru 22, ma nistax biss

1137
00:49:04,660 --> 00:49:06,620
jaqbżu għal xi ħaġa xi ħaġa parentesi.

1138
00:49:06,620 --> 00:49:10,530
Għandi li tħares fuq il-lista, ħafna
bħal eżempji tiftix tagħna linearment,

1139
00:49:10,530 --> 00:49:12,260
biex issib in-numru 22.

1140
00:49:12,260 --> 00:49:14,340
Allura aħna jidhru li jkunu ħallsu prezz hemmhekk.

1141
00:49:14,340 --> 00:49:16,430
Iżda nistgħu madankollu
isolvu problemi oħra.

1142
00:49:16,430 --> 00:49:18,587
>> Fil-fatt, let me jintroduċu
biss ftit visuals.

1143
00:49:18,587 --> 00:49:20,920
Mela jekk inti kont qed isfel sa
Mather tal Dining Hall reċentement,

1144
00:49:20,920 --> 00:49:23,320
inti ser tfakkar li tagħhom
munzelli ta 'dixxijiet bħal dan,

1145
00:49:23,320 --> 00:49:26,300
aħna mislufa dawn mill
Annenberg qabel klassi.

1146
00:49:26,300 --> 00:49:28,930
Allura dan munzell ta 'dixxijiet, għalkemm,
huwa rappreżentattiv fil-fatt

1147
00:49:28,930 --> 00:49:30,860
ta 'struttura data xjenza tal-kompjuter.

1148
00:49:30,860 --> 00:49:32,910
Hemm struttura data
fix-xjenza tal-kompjuter

1149
00:49:32,910 --> 00:49:38,010
magħrufa bħala munzell li ħafna nicely
jippresta ruħu għal eżattament dan viżwali.

1150
00:49:38,010 --> 00:49:41,380
Mela jekk kull wieħed minn dawn trejs mhix
trej iżda bħal numru u xtaqt

1151
00:49:41,380 --> 00:49:45,010
taħżen numri, I
tista 'tpoġġi waħda stabbiliti hawn,

1152
00:49:45,010 --> 00:49:48,320
u I tista 'tpoġġi ieħor stabbiliti hawn,
u tkompli stivar numri

1153
00:49:48,320 --> 00:49:53,180
fuq quċċata ta 'xulxin, u x'hemm
potenzjalment utli dwar dan

1154
00:49:53,180 --> 00:49:55,450
hija li x'inhu l-implikazzjoni
din l-istruttura data?

1155
00:49:55,450 --> 00:49:58,045
Liema numru nista iġbed
ewwel l-aktar konvenjenti?

1156
00:49:58,045 --> 00:50:00,640

1157
00:50:00,640 --> 00:50:03,030
L-aktar reċentement poġġiet wieħed fuq hemmhekk.

1158
00:50:03,030 --> 00:50:06,430
>> Allura dan huwa dak li aħna kieku ssejjaħ fil
xjenza tal-kompjuter struttura data LIFO.

1159
00:50:06,430 --> 00:50:08,070
Aħħar li l-ewwel out.

1160
00:50:08,070 --> 00:50:10,800
U aħna ser tara qabel twil għaliex
li jista 'jkun utli iżda għal issa,

1161
00:50:10,800 --> 00:50:12,200
biss tikkunsidra l-proprjetà.

1162
00:50:12,200 --> 00:50:15,158
U huwa tip ta 'stupid jekk taħseb
dwar kif il-sala dining tagħmlu.

1163
00:50:15,158 --> 00:50:17,910
Kull darba li trays nodfa u
tpoġġi dawk reëenti fuq,

1164
00:50:17,910 --> 00:50:22,160
inti jista 'jkollhom qabel nadif
iżda eventwalment ħafna maħmuġ u trab

1165
00:50:22,160 --> 00:50:24,360
trej fil-qiegħ nett
attwalment jekk int qatt

1166
00:50:24,360 --> 00:50:26,820
jasal sal-qiegħ ta 'dak
munzell, għaliex inti biss

1167
00:50:26,820 --> 00:50:29,380
iżommu tqegħid l-ġodda u
dawk nodfa fuq quċċata ta 'dan.

1168
00:50:29,380 --> 00:50:31,840
L-istess ħaġa jista 'jiġri
f'supermarkit wisq.

1169
00:50:31,840 --> 00:50:35,450
Jekk għandek każ display
ta 'ħalib u kull CVS darba

1170
00:50:35,450 --> 00:50:37,610
jew min gets aktar ħalib,
inti biss shove l ħalib

1171
00:50:37,610 --> 00:50:39,880
diġà għandek għall-dahar u
inti tpoġġi l-ġodda bil-quddiem,

1172
00:50:39,880 --> 00:50:43,088
int se jkollhom xi pretty diżgustanti
ħalib fl-aħħar tal-istruttura tad-data,

1173
00:50:43,088 --> 00:50:46,390
għaliex dan huwa dejjem fil-qiegħ jew
ekwivalenti huwa dejjem fuq wara.

1174
00:50:46,390 --> 00:50:50,407
>> Imma hemm mod ieħor biex jaħsbu dwar
lining up data u per eżempju, dan.

1175
00:50:50,407 --> 00:50:53,490
Jekk int wieħed minn dawk in-nies li jħobb
għal-linja up barra ta 'ħwienet Apple

1176
00:50:53,490 --> 00:50:55,610
meta prodott ġdid jidħol
out, int probabilment

1177
00:50:55,610 --> 00:50:58,780
mhux permezz ta 'teknika munzell
istruttura għaliex inti

1178
00:50:58,780 --> 00:51:03,070
se jaljenaw kulħadd li huwa
lining sa tixtri xi ġugarell il-ġdid.

1179
00:51:03,070 --> 00:51:06,610
Pjuttost, int probabilment tuża
liema tip ta 'struttura data

1180
00:51:06,610 --> 00:51:10,050
jew liema tip ta 'sistema
fid-dinja reali?

1181
00:51:10,050 --> 00:51:13,493
Nisperaw huwa linja, jew aktar
sew jew aktar British simili, kju.

1182
00:51:13,493 --> 00:51:17,700
U jirriżulta kju hija wkoll
istruttura tad-data fix-xjenza tal-kompjuter,

1183
00:51:17,700 --> 00:51:19,700
iżda kju għandha ħafna
proprjetà differenti.

1184
00:51:19,700 --> 00:51:20,820
Mhuwiex LIFO.

1185
00:51:20,820 --> 00:51:21,990
Aħħar li l-ewwel out.

1186
00:51:21,990 --> 00:51:22,800
Alla jipprojbixxu.

1187
00:51:22,800 --> 00:51:24,280
Huwa minflok FIFO.

1188
00:51:24,280 --> 00:51:26,110
Ewwel, l-ewwel barra.

1189
00:51:26,110 --> 00:51:27,970
U li l-ħaġa tajba
għall-ġustizzja fini "

1190
00:51:27,970 --> 00:51:30,428
ċertament meta int inforra
up super kmieni fil-għodu.

1191
00:51:30,428 --> 00:51:33,400
Jekk ikollok hemm l-ewwel, inti
tixtieq li toħroġ l-ewwel kif ukoll.

1192
00:51:33,400 --> 00:51:35,880
>> U hekk kollha ta 'din id-dejta
istrutturi, kjuwijiet u stacks

1193
00:51:35,880 --> 00:51:39,220
u għenieqed ta 'oħrajn, jirriżulta inti
tista 'taħseb ta' dan bħala biss firxa.

1194
00:51:39,220 --> 00:51:41,820
Dan huwa firxa, forsi
daqs fiss 4, iżda d

1195
00:51:41,820 --> 00:51:44,990
jkun it-tip ta 'sbieħ jekk nistgħu biss pile
trejs kważi infinitament tall jekk aħna

1196
00:51:44,990 --> 00:51:46,780
jkollhom li trejs ħafna jew numri.

1197
00:51:46,780 --> 00:51:48,840
Allura forsi rridu
jużaw lista marbuta hawn,

1198
00:51:48,840 --> 00:51:51,800
iżda l-kompromess se tkun
potenzjalment li għandna bżonn memorja aktar,

1199
00:51:51,800 --> 00:51:55,930
jieħu ftit aktar ħin, iżda aħna
ma jillimitawx l-għoli tal-munzell,

1200
00:51:55,930 --> 00:51:59,550
ferm simili display każ Mather ta
jista jillimitaw id-daqs tal-munzell,

1201
00:51:59,550 --> 00:52:03,117
u għalhekk dawn huma deċiżjonijiet ta 'disinn jew
għażliet disponibbli lilna finalment.

1202
00:52:03,117 --> 00:52:04,950
Allura ma din id-data
istrutturi, konna beda

1203
00:52:04,950 --> 00:52:09,360
jaraw limiti ta 'fuq ġodda potenzjalment
fuq dak li qabel kien super fast

1204
00:52:09,360 --> 00:52:11,260
u fejn aħna ser jitilqu
off llum u fejn

1205
00:52:11,260 --> 00:52:13,200
aħna ser tama li tikseb sa
hija l-Erbgħa, aħna ser

1206
00:52:13,200 --> 00:52:15,740
tibda tħares lejn data
struttura li tikri us tfittxija

1207
00:52:15,740 --> 00:52:18,260
permezz ta 'data fi log aħħar ħin mill-ġdid.

1208
00:52:18,260 --> 00:52:21,470
U rajna li, jfakkru, fl zero ġimgħa
u wieħed bil-tfittxija binarju jew aqsam

1209
00:52:21,470 --> 00:52:22,180
u conquer.

1210
00:52:22,180 --> 00:52:26,240
Huwa li ġejjin lura u aħjar għadhom,
l-Grail qaddis għal dan l-erbgħa

1211
00:52:26,240 --> 00:52:29,510
se jkun li toħroġ il-
istruttura tad-data li timxi verament

1212
00:52:29,510 --> 00:52:32,070
jew teoretiku fil
ħin kostanti, fejn

1213
00:52:32,070 --> 00:52:34,760
ma jimpurtax kemm
miljuni jew biljuni ta 'affarijiet

1214
00:52:34,760 --> 00:52:38,470
għandna fl-istruttura tad-data, se
jqarrbuna ħin kostanti, forsi pass wieħed

1215
00:52:38,470 --> 00:52:41,387
inkella tnejn jew 10 passi,
iżda numri kostanti ta 'passi

1216
00:52:41,387 --> 00:52:42,970
li tfittex li struttura tad-data.

1217
00:52:42,970 --> 00:52:46,300
Li fil-fatt se tkun l-Grail qaddis
iżda aktar fuq li nhar l-Erbgħa.

1218
00:52:46,300 --> 00:52:49,045
Ara ya imbagħad.

1219
00:52:49,045 --> 00:52:53,704
>> [Daqq tal-mużika]

1220
00:52:53,704 --> 00:56:08,448