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>> SPEAKER 1: Ejja jikteb programm li
gets string mill-utent mingħajr

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jużaw il-Librerija CS50
jiffunzjonaw GetString.

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Biex tagħmel dan, aħna ser imorru quddiem u l-użu
scanf, il-funzjoni li l-GetString

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funzjoni effettivament juża
taħt il-barnuża.

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Imma jien ser jagħmlu dan deliberatament
b'mod Buggy.

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Jien ser tagħmel b'mod li naħseb
ikun ġust, iżda jirriżulta li

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suppożizzjoni tiegħi għaddej biex
pjuttost, pjuttost difettuż.

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U fil-fatt, pjuttost perikolużi.

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Minħabba bugs bħal dak li jien ser
jagħmlu jistgħu jiġu sfruttati minn avversarji

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tali li l-apparat tiegħek jew program tiegħek
jista 'jittieħed potenzjalment.

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>> Ejja tibda kif ġej.

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Ewwel ejja tiddikjara string tagħna,
inkella magħruf issa bħala stilla char,

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u sejħa hija s.

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Tikri l-utent għal string li jmiss fil-pront,
kif ma "string jekk jogħġbok." U

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ejja issa jiksbu l-sekwenza mill-utent
jużaw scanf, kwotazzjoni unquote, "% s." Fil

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kliem ieħor, ejja tinforma scanf li aħna
do fil-fatt tistenna li tikseb string

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mill-utent.

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>> Imma issa għandna bżonn li tgħid scanf
Ħaġa waħda oħra -

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fejn tpoġġi l-sekwenza li
l-utent jipprovdi.

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Well, jien ser sempliċiment tibda
ma 'comma s, li tispeċifika li nixtieq

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scanf li jpoġġi l-string hemmhekk.

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Jien jmiss ser jistampa xi ħaġa
bħal printf "grazzi għall-% s

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comma backslash n. "U kif dejjem, jien
ser jgħaddu fil-sekwenza, s.

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Issa ejja jiffrankaw, tiġbor, u run dan
programm, u ara jekk aħna ma jistgħu jinduċu

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l-problema I mbassra.

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>> Agħmel scanf-1.

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./scanf-1.

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String jekk jogħġbok.

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Ejja jipprovdi xi ħaġa simili, "bonjour."
"Grazzi għall-null." Hmm, li mhux

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dak Jien kont qed nistenna.

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Allura x'inhu għaddej hawn?

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>> Ukoll, jirriżulta għaliex aħna dikjarat
i bħala stilla char iżda aħna ma

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attwalment maħżuna s-indirizz ta '
blokki attwali tal-memorja, scanf ma

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ikollhom kullimkien biex tpoġġi l-sekwenza
li l-utent ittajpjat pulzieri

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Tabilħaqq, jekk l-utent kellhom issa tip fil
string ħafna itwal minn "hello,"

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per eżempju diversi linji ta 'test jew
diversi paragrafi ta 'test, huwa pjuttost

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possibbli li nistgħu jinduċu
hekk imsejħa tort segmentazzjoni.

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>> Minħabba scanf mhix se tkun taf li
I ma attwalment tqiegħed l-indirizz

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ġewwa ta 's.

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Pjuttost, huwa se tara xi valur
fil-i, xi mudell ta 'bits li jista'

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jkun tajjeb ħafna valur żibel,
hemm biss b'kumbinazzjoni.

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U scanf għadu għaddej biex tipprova tikteb
l-sekwenza utent f'dak l-indirizz,

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anki jekk huwa valur żibel, li
tabilħaqq jista 'jinduċi crash.

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>> Allura kif huma aħna se jiffissaw dan?

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