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>> Zamyla Chan: Hebu kuangalia mikopo yako.

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Katika tatizo hili, tutaweza kuchochea mtumiaji
kwa mchango wa idadi ya kadi.

4
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Kisha tutaweza kukimbia kwamba kadi
idadi ili kuona kama ni halali.

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00:00:10,090 --> 00:00:13,430
Kama ni hivyo, tutaweza magazeti kampuni
kwamba kadi ni mali ya.

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00:00:13,430 --> 00:00:17,520
Vinginevyo, tutaweza kuwaambia user
kwamba kadi ambayo ni batili.

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>> Hebu tuzame katika na
kusababisha kwa ajili ya pembejeo user.

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kadi namba ni
ya data aina long_long,

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hivyo kazi CS50 maktaba
get_long_long itakuwa muhimu kabisa.

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Lakini kazi hii kuhakikisha kwamba
mtumiaji pembejeo integer yoyote.

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Hivyo integers yoyote chanya, hasi
integers, au sifuri ni wote faini.

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Hivyo juu yako na zaidi
kuhalalisha kama au si

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user ametupa halali
Kadi aina idadi.

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>> Sasa kwa kuwa tuna kadi
idadi kutoka kwa mtumiaji, basi

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tunahitaji mahesabu checksum.

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Hivyo checksums kadi
ni mahesabu kama ifuatavyo.

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Kuanzia pili kwa tarakimu ya mwisho,
sisi kuzidisha kila tarakimu wengine na 2.

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Kisha sisi kuongeza wale
bidhaa 'tatu kwa pamoja.

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Kutokana na hali hiyo sisi kuongeza
Jumla ya tarakimu kwamba

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walikuwa si tele na 2 kwa kuwa
Jumla uliopita kwamba sisi mahesabu.

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Mwisho, kama idadi hiyo kuishia
katika 0, kisha namba ni halali.

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>> Hebu kwenda kwa njia mfano
na kuchukua hatua hii kwa hatua.

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Hivyo hatua yetu ya kwanza ni kuanza
kutoka ya pili ya tarakimu iliyopita

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na kuzidisha kila tarakimu wengine wawili.

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Sasa, kama mimi kuhifadhiwa kadi
idadi katika variable kuitwa CC posta,

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kisha modding kwamba kwa 10 ingekuwa
nipe tarakimu ya mwisho.

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Hivyo jinsi gani upatikanaji
pili kwa tarakimu ya mwisho?

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>> OK, hivyo mara moja tumekuwa kupatikana
pili kwa tarakimu ya mwisho,

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kisha tutaweza iterate kupitia
kuzidisha kila tarakimu wengine na 2.

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Mara sisi kuwa na kwamba, basi
tutaweza kuchukua bidhaa hizo

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na kuongeza tarakimu wale bidhaa 'pamoja.

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Hivyo hapa nina single
tarakimu, hivyo hiyo ni faini.

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Lakini basi mara moja mimi kupata mwisho wangu
number-- 7 tele na 2--

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Mimi kuongeza 1 na 4 kwa kunipa 27.

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Kutoka huko, sisi kuongeza kwamba product--
27-- na jumla ya tatu kwamba

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walikuwa si tele na 2.

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>> Hivyo hapa nimekuwa yalionyesha zote
ya idadi ya wale katika rangi ya machungwa.

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Mara sisi kuongeza tarakimu hayo, basi
sisi kupata yetu checksum idadi ya mwisho.

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Hivyo sisi kuhalalisha hivyo kwa kufanya
kuhakikisha kwamba tarakimu ya mwisho ni 0.

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Kama checksum haina mwisho katika
0, kisha namba ya kadi ya mkopo

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ni dhahiri batili.

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Vinginevyo, hebu kwenda kwenye
kuangalia vitambulisho vya kampuni

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na kadi namba urefu.

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>> Tumekuwa zinazotolewa orodha
ya makampuni ya tatu,

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pamoja na kwamba, idadi ya integers
kwamba idadi ya kadi zao na.

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Kisha kwanza tarakimu mbili kwamba
kadi hizo inaweza kuanza na.

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Hivyo juu yako na kuweka wimbo wa
kwanza tarakimu mbili za kadi ya mkopo

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na idadi ya integers katika kadi hiyo.

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Na kwa kuwa, wameweza
kumaliza tatizo.

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Jina langu ni Zamyla, na hii ilikuwa ya Mikopo.

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