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[Powered by Google Translate] Chris Gerber: Yon fonksyon se yon seri etap ki nan yon

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pi gwo pwogram, ki se nòmalman fèt yo dwe rele

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plizyè fwa, epitou soti nan kote plizyè lòt nan

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pwogram nan.

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Lè y ap kreye yon fonksyon C, youn nan kondisyon yo ki se

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presize yon kalite valè retounen.

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Ka a pi senp se yon sitiyasyon kote w rele a

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kòd se pa sa konsène ak rezilta a nan fonksyon an.

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Sa a ta kapab ka a lè n ap enprime done a

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ekspozisyon itilizatè a, menm jan ak printf.

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Nan ka sa a, nou ka deklare yon valè retou

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yo dwe nan anile kalite.

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Sèvi ak anile tou senpleman di du a ke pa gen okenn

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valè ap retounen.

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Ann gade pou wè ki sa sa a sanble.

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>> Se pou nou di ke nou gen yon fonksyon ki rele say_hello ki

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pran youn agiman.

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Nou pral pase l non yon moun nan epi li pral afiche yon salitasyon

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sou ekran an.

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Non a pral nan * kalite Char.

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Epitou, n ap presize ke kòm agiman an.

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Aplikasyon mwen an pa bezwen konnen sa ki te enprime oswa si li

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te enprime.

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Se konsa, valè a retounen yo pral nan anile kalite.

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Sa a fonksyon ka enprime ekran an ak yon lòd tankou

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printf ("Hello,% s \ n

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", Non);.

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Ap salitasyon a ap parèt ak kontwòl yo pral pase

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Retounen nan kòd la rele.

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Youn nan bagay sonje se ke lè kalite a valè retou se anile,

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ou pa bezwen gen ladan yo yon retou

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deklarasyon nan fonksyon an.

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Si ou chwazi gen ladan yo yon sèl, pa enkli yon valè retou

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kòm yon agiman.

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>> Nan kèk ka, li fè sans nan retounen yon

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valè soti nan yon fonksyon.

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Se pou nou di ke nou te ekri yon fonksyon rele add_floats.

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Nou pral pase l de prèv, tou de flote,

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rele premye ak dezyèm.

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Epi li pral di nou sa sòm total la nan tout sa yo flote se.

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Nou konnen ke si nou ajoute de cha ansanm, rezilta a

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pral gen yon flote.

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Bay sa yo, nou chwazi yon kalite retounen nan flote.

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Sa a fonksyon pral fè sa nou kalkile a epi retounen

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valè yo nan yon deklarasyon tankou retou

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premye + dezyèm;.

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Lè kontwòl la transmèt tounen nan kòd la rele, nan

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ki kapab lakòz valè se kounye a disponib ak sa yo ki kòd.

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Nou ka magazen sa a valè tankou konsa: rezilta flote =

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add_floats (3.14, 1,62

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);.

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Rezilta nan ka sa a ta kounye a gen ladan valè a 4,76.

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>> Kòm yon rapèl, valè pwen k ap flote yo se enpresizyon.

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Se konsa, si sa a se te yon kalkil finansye, lè l sèvi avèk dola ak

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santim, nou ka vle konsidere yon egzak done kalite tankou

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Int ak fè kalkil la nan peni.

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>> Yon lòt ka kote nou ta vle retounen yon valè ki sòti nan yon

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fonksyon se lè nou vle konnen si yon fonksyon te

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siksè.

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Si li te pa reyisi, nou ka vle tou konnen ki kalite

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erè te fèt la.

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Se pou nou di ke nou ap eseye louvri yon dosye sou ki gen kapasite nan konte

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nimewo a nan karaktè nan li.

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Si dosye a pa ka louvri, nou vle pou kapab sispann ak

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di itilizatè a sou pwoblèm nan.

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>> Nou pral rele count_file_chars fonksyon nou yo ak li pral

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pran yonn agiman.

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Nou pral pase nan non dosye a lè l sèvi avèk yon

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Char * rele fichier.

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Sa a fonksyon ta ka gade yon bagay tankou sa a.

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Nan egzanp sa a, nou ta atann konte a tounen nan

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dwe 0 oswa pi plis.

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Sa a fèy nou nonm antye relatif yo negatif

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itilize kòm valè Sentinel.

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Yon valè Sentinel se senpleman yon valè espesyal ki se pa

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done lejitim men transmèt enfòmasyon.

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Isit la, si mwen tounen yon -1 al nan kòd la rele, se mwen menm

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aktyèlman voye mesaj la ke yon erè ki te fèt pandan y ap

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ap eseye gen aksè a dosye a.

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Mwen te kapab Lè sa a, tcheke ki valè retounen nan detèmine si mwen

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rele nan fonksyon te gen siksè.

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Si nimewo a te 0 oswa pi plis, mwen ta konnen an

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nimewo nan karaktè nan dosye a.

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Si, toutfwa, kantite a te mwens pase 0, mwen te kapab tou senpleman

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enprime sa ki te yon pwoblèm ki te fèt.

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Youn nan komès-off yo konsidere se ke lè rezève nan tout

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valè negatif kòm valè Sentinel, an konsideran sa a se yon

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32-bit nonb antye relatif, mwen te esansyèlman wete alantou

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2 milya dola valè retou posib.

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>> Kalite valè retounen yo se youn nan eleman ki nan pi enpòtan

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fonksyon apèl.

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Èspere ke sa a te BECA kout te ede ou panse osijè de

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twa kalite kle: anile, valè rezilta, ak valè Sentinel,

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ak ki lè chak nan twa a ta kapab

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apwopriye nan kòd ou a.

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Mèsi pou gade.