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>> [Halisi kucheza]

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>> ZAMYLA CHAN: Je, wewe badala kupokea
$ 10,000,000 sasa hivi au kupokea

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pennies kila siku ya mwezi, ambapo
kila siku baadae, kupokea

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mara mbili ya kiasi cha wewe pennies
kupokea siku kabla?

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Katika pennies, tunakwenda
kuthibitisha kwa nini ni lazima

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dhahiri kuchukua pennies.

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Kazi yako ni kuandika pennies.c--

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mpango kwamba kwanza anauliza jinsi ya mtumiaji
siku nyingi zilizopo katika mwezi na

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kisha anauliza jinsi wengi pennies mtumiaji
atapokea siku ya kwanza.

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mpango lazima basi mahesabu
kiasi kwamba mtumiaji itakuwa na

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kusanyiko mwishoni mwa
mwezi na kuonyesha ni.

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>> Tunaweza kuvunja mpango huu hadi
katika michache ya kazi.

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Tutaweza haja ya haraka kwa
nyingi mtumiaji wa pembejeo -

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siku na miezi, na pennies
siku ya kwanza.

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Tunahitaji kuweka wimbo wa kiasi gani cha fedha
user ana na update kila

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siku, mara mbili ya kiasi cha
pennies kwamba wao kupokea.

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Na hatimaye, sisi magazeti yao
mwisho jumla, katika dola.

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>> Hebu kukabiliana user pembejeo kwanza.

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Mimi naenda kufungua apples.c,
short mpango kwamba mikataba

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na pembejeo na mazao.

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Saa ya juu hapa, nimekuwa ni pamoja na baadhi
ya maktaba kwamba mimi haja -

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Maktaba CS50 na kiwango
I / O maktaba.

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Mimi magazeti haraka kwa kutumia
printf kazi kutoka

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kiwango I / O maktaba.

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Lakini halisi uvuvio wa mtumiaji
kinatokea katika mstari wa pili na hii

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GetInt kazi katika maktaba CS50.

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>> GetInt inapata pembejeo kutoka kwa mtumiaji na
kuhakikisha kwamba pembejeo ni integer.

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Hivyo mimi kuhifadhi pembejeo mtumiaji katika integer
i, toa 1 kutoka i, na kisha

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magazeti nje thamani mpya kama i.

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Baada ya kuandaa apples.c kutumia
amri ya "kufanya mapera," Nina

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executable file apples.

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Mbio kwamba, mimi itabidi pembejeo 1.

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mpango ananiambia kwamba
Nina apples 0 kushoto.

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Na hivyo kuwa kufanya kazi kama ilivyotarajiwa.

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>> Basi hebu kukimbia hii tena
na pembejeo hasi 1.

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Sasa, baada ya kiasi hasi ya apples
kweli haina mantiki, lakini

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mpango anapokea yake, kwa sababu hasi
1, vizuri, ni integer.

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Na sasa mpango au monster
ndani ya mpango anakula hasi

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apple, na sasa nina
hasi 2 apples.

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Hm, hivyo kwamba ni somo moja -

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hata ingawa kazi GetInt na
kuhusiana kazi, kama GetFlow au

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GetString kupata data haki ya aina, wewe
kuhakikisha kwamba pembejeo hufanya

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maana kwa ajili ya programu yako.

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>> Katika pennies, itakuwa si kufanya tu haraka
kwa integer, itabidi kufanya

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uhakika kwamba mtumiaji pembejeo integer
kwamba kufanya maana kupewa mazingira.

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Mwezi inaweza tu kuwa na 28,
29, 30, au siku 31.

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Tunataka kuendelea kudai
integer halali.

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Kama wao pembejeo nje integer ya yetu ya
mipaka kukubalika, tutaweza kuwashawishi

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tena na tena, mpaka
kutupatia integer halali.

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>> Kukumbuka "kurudia mpaka"
kuzuia katika Scratch?

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Unaweza kufanya kujenga sawa
katika C kutumia "wakati" kitanzi

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au "kufanya-wakati" kitanzi.

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kitanzi wakati muundo ina hali
kwamba lazima walikutana kwa ajili ya

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mwili wa kitanzi kutekeleza.

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>> Hii inapaswa kuangalia kidogo sawa,
kwa sababu hali ni kama

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Mwanzo vitalu na pembe
na huenda katika mabano

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ya "wakati" kitanzi.

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Hivyo sharti kwamba kuangalia kama
integer ni ndani ya

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mipaka sahihi.

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Unaweza kuchochea integer kutumia GetInt
na kisha kutekeleza yako "wakati"

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kitanzi, kurudia haraka na uchapishaji
maelekezo, wakati pembejeo

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si halali.

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>> Njia nyingine ya kuhakikisha sahihi user pembejeo
ni kwa kutumia "kufanya-wakati" kitanzi,

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ambayo ni sawa na kitanzi Wakati.

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"Kufanya-wakati" kitanzi executes kanuni
ndani ndio mwili na kisha hundi

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kama hali ni alikutana au la.

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Hii ni muhimu kwa ajili ya kupata user pembejeo,
kwa sababu unajua kwamba unahitaji

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kuwashawishi angalau mara moja.

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Kama hali ni kukutana, mpango
nitafanya line baada ya

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yako "kufanya-wakati" kitanzi.

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Kama hali ni alikutana ingawa,
kitanzi kurudia

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>> "Kufanya-wakati" kitanzi kwa valideringen mtumiaji
pembejeo itakuwa kuangalia kitu kama hiki.

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Mimi kutangaza n kutofautiana, GetInt, na
kisha kurudia mpaka n ni halali.

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Na mchakato huu, nilivyoeleza, ilikuwa kutumia
aina integer-data, ambayo

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itabidi kutumia kwa siku ya mwezi.

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Lakini tunajua kwamba idadi ya pennies
itakuwa rundo juu haraka, hivyo ili

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kuhifadhi idadi kubwa, kutumia aina data
Longlong, lakini kumbuka huo

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kanuni ya uthibitisho inatumika.

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>> Kushangaza, hivyo mara moja tuna mbili halali
pembejeo kutoka user -

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siku katika mwezi na pennies
Siku ya kwanza -

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tunaweza kuhamia kwenye ijayo
sehemu ya mpango.

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siku ya kwanza, user huanza na
hata hivyo wengi wao pennies maalum

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na kiasi cha fedha dinari kwamba wao
kupokea siku ya pili ni mara mbili.

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Hivyo inafanya hisia kwa kuweka wimbo
ya hizi kiasi mbili -

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fedha kiasi gani mtumiaji ana na jinsi
pennies wengi wao itabidi itolewe.

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>> Sasa, kufanya kitu kwa muda wa siku 28-31
ni repetitive, hivyo hebu kutumia "kwa"

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kitanzi kwa iterate zaidi ya siku katika
mwezi, uppdatering taarifa na senti

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kiasi kila wakati.

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"Kwa" kitanzi syntax ina
yafuatayo -

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initialization, hali,
na update.

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Yako "kwa" kitanzi itakuwa initialize
kutofautiana, wakati

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kwanza inaingia kitanzi.

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Kama hali ni alikutana, mwili
ya kitanzi nitafanya.

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Baada ya hapo, update nitafanya.

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Kama hali bado ni alikutana,
kitanzi nitafanya na update, na

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kurudia, kwa muda mrefu kama hali yako
kutathmini kwa kweli.

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>> Hapa ni "kwa" kitanzi kwamba mgawanyiko
integer p na 2 jumla ya mara 10.

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Kumbuka jinsi mimi alitangaza p integer
nje ya yangu kitanzi "kwa", ili kwamba

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integer unaweza kuwa kupatikana
nje kitanzi "kwa".

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Baada ya mwezi amepita, ni wakati
kuwaambia mtumiaji fedha kiasi gani

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wameweza kujipatia.

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Kwa spec, unahitaji kuwaambia mtumiaji
wangapi dola, si jinsi wengi

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pennies, wana.

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Lakini hadi sasa, ve naendelea wimbo wa
taarifa na pennies kutumia LongLongs,

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ambayo ni namba nzima.

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>> Kuna pennies 100 na $ 1, hivyo isipokuwa
idadi ya pennies ni

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mbalimbali ya 100, itabidi
kuwakilisha maeneo decimal.

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autotype maradufu inaruhusu
wewe kufanya hili.

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Hivyo ni jinsi gani sisi kubadilisha kutoka anayewakilisha
pennies kwa dola?

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>> Hebu tuangalie pi.c.

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Mpango huu inachukua big_pi longlong na
mgawanyiko ni kwa 100,000, na Prints

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matokeo kwa maeneo decimal tano.

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Kama sisi alitaka kuonyesha nne decimal
maeneo, basi tunaweza tu kuchukua nafasi hii

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simu hapa.

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Basi hebu kuokoa, kukusanya pi, na
basi kuona matokeo, ambayo sisi

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wanatarajia kuwa 3.1415 -

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mitano ya kwanza ya maadili ya pi.

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>> Siyo ingawa.

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Na kwa nini?

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00:07:07,390 --> 00:07:11,920
Naam, kwa sababu ni big_pi longlong,
ambayo ni idadi nzima, ambayo si

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kuweka wimbo wa decimals.

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muundo nahitaji
kufanya ni katika mgawanyiko.

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Mimi haja ya kutupwa kwa mara mbili hapa kabla ya
kugawa, kwa sababu mara mbili hawezi kuweka

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wimbo wa maeneo decimal.

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Na mimi nina kwenda kuongeza line mpya
hapa kwa formatting bora.

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00:07:28,080 --> 00:07:33,090

128
00:07:33,090 --> 00:07:34,230
>> Na hapa tuna yake -

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00:07:34,230 --> 00:07:37,660
3.1416.

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00:07:37,660 --> 00:07:43,520
Unaweza taarifa kwamba Prints 3.1416
badala ya 3.1415 kama ilivyotarajiwa.

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Hiyo ni kwa sababu wakati wa raundi
mgawanyiko mchakato, kinyume na tu

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truncating thamani.

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Sasa unapaswa kuwa na uwezo wa magazeti
mwisho taarifa kwa usahihi, ambayo finishes

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mpango.

135
00:07:54,870 --> 00:07:55,930
>> Hongera.

136
00:07:55,930 --> 00:07:57,340
Jina langu ni Zamyla.

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00:07:57,340 --> 00:07:58,720
Na hii ilikuwa pennies.

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00:07:58,720 --> 00:08:05,589
>> [Halisi kucheza]