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[Powered by Google Translate] JORDAN JOZWIAK: Kalite Distribisyon an, nan sans ki pi senp, se yon

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fason yo chanje entèpretasyon yon òdinatè a nan kèk done pa

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chal oswa fòmèlman chanje kalite done li yo.

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Tankou chanje yon int nan yon flote, oswa vis vèrsa.

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Pou konprann Distribisyon kalite, nou bezwen

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kòmanse ak atik debaz yo -

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done kalite tèt yo.

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Nan langaj konpitè tankou C, tout varyab gen kèk sòt

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nan done kalite ki detèmine kouman òdinatè a, ak menm jan an tou

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itilizatè a, entèprete varyab sa a.

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Done nimerik kalite tankou yon int, flote long long, ak

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doub, tout gen karakteristik pwòp yo inik ak se

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itilize yo presize valè divès kalite chenn ak presizyon.

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Distribisyon Kalite pèmèt nou pran yon nimewo pwen k ap flote tankou

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3.14 epi pou yo jwenn pati a anvan desimal a, 3 nan ka sa a,

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pa depoze li nan yon int.

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Ann pran yon egzanp soti nan lang angle a pou yon brèf

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revize kalite, ak wè kouman kalite Distribisyon kapab chanje

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wout la nou entèprete yon moso nan done.

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Pou done, kite a pran senbòl yo isit la.

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Mwen te jis, al gade nan liy sa yo ak anpil atansyon configuré kòm

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senbòl, men kòm yon moun ki konnen lang angle a,

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ou imedyatman rekonèt ke yo ye a, an reyalite, lèt yo.

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Ou chal konprann kalite a done.

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Gade sa a fil de lèt nou ka wè de

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mo diferan, yo chak ak siyifikasyon pwòp li yo.

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Genyen nan non la, van, tankou nan van an ap deyò.

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Ak gen nan vèb la, van, tankou nan mwen bezwen

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van gade analogique m 'yo.

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Sa a se yon egzanp enteresan, paske nou ka wè

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ki jan kalite la ke nou transfere bay done nou an, si non oswa

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vèb, chanjman ki jan nou itilize ke done -

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kòm van an mo oswa van.

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Malgre ke yon òdinatè pa pran swen sou gramè ak pati

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lapawòl angle, prensip la menm debaz aplike.

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Sa se, nou kapab chanje rèv la vle egzak la

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done menm ki estoke nan memwa pa senpleman depoze li nan yon

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diferan kalite.

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Isit la yo se gwosè yo nan kalite ki pi komen sou yon 32 ti jan-

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opere sistèm.

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Nou gen yon Char nan 1 int multiple, ak flote nan 4 bytes, yon long

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long ak yon doub nan 8 bytes.

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Paske yon int pran moute 4 bytes, li pral pran 32 Bits

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lè li se ki estoke nan memwa kòm yon seri binè

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nan zewo ak inite.

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Pandan tout tan kòm varyab nou rete kòm yon int nan kalite,

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òdinatè ap toujou konvèti sa yo yo menm ak zewo soti nan

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binè nan nimewo orijinal la.

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Sepandan, nou te ka teyorikman jete sa yo 32

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Bits nan yon seri de kalite Boolean.

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Lè sa a, òdinatè a pa t 'ankò wè yon nimewo, men

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olye yon koleksyon zewo ak inite.

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Nou te ka tou eseye li sa done kòm yon nimerik diferan

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tape, oswa menm kòm yon afè de kat karaktè.

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Lè gen rapò ak nimewo yo nan Distribisyon, ou dwe konsidere kouman

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pral presizyon la ki gen valè ou a ap afekte.

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Kenbe nan tèt ou ke presizyon la kapab rete menm jan an,

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oswa ou ka pèdi presizyon, men ou pa janm ka jwenn presizyon.

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Ann al nan pou twa fason yo ke ou kapab ki pi komen

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pèdi presizyon.

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Depoze yon flote nan yon int ap lakòz tronkatur nan tout bagay

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apre pwen desimal la, kidonk, ou ap kite

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avèk nimewo a tout antye.

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Si nou pran x lan flote ki pral egal a 3.7, nou ka jete

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sa a x varyab nan yon int pa senpleman ekri int nan

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parantèz.

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Chak fwa nou itilize tèm sa a isit la, nou pral efektivman

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dwe lè l sèvi avèk valè a twa paske nou te twonke

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tout bagay apre pwen desimal la.

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Nou kapab tou konvèti yon long long nan yon int, ki pral yon

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Menm jan an mennen nan yon pèt a-wo lòd miyèt moso.

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Yon long tan pran moute 8 bytes, oswa 64 Bits nan memwa.

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Se konsa, lè nou voye l 'jete nan yon int ki te sèlman gen 4 bytes, oswa 32

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Bits, n ap esansyèlman découper koupe tout Bits yo ki

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reprezante valè yo binè pi wo.

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Ou kapab tou voye yon doub nan yon flote, ki pral bay

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ou flote nan ki pi pre posib doub a san yo pa

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nesesèman awondi li.

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Menm jan ak lontan lontan nou yo konvèsyon Int, pèt la nan

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presizyon se paske yon doub gen plis done.

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Yon doub pral pèmèt ou nan magazen 53 Bits enpòtan,

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apeprè 16 chif enpòtan.

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Lè nou konsidere ke yon flote pral sèlman pèmèt ou nan magazen 24

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Bits siyifikatif, apeprè sèt chif enpòtan.

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Nan sa yo de ka ki sot pase yo, li kapab itil panse a

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tape Distribisyon kòm rèsizin yon foto.

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Lè ou ale nan yon gwosè gwo nan yon gwosè ti, ou pa ka wè

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bagay sa yo kòm byen klè paske ou pèdi done

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nan fòm lan nan piksèl.

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Distribisyon Kalite kapab lakòz tou pwoblèm pou lè nou

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jete antye flote.

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Depi flote sou yon machin 32-bit sèlman gen 24

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Bits siyifikatif, yo pa ka avèk presizyon reprezante valè

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plis pase 2 a pouvwa a nan 24, oswa 16777217.

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Koulye a, kite nan pale sou Distribisyon eksplisit ak enplisit.

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Distribisyon eksplisit se lè nou ekri kalite a nan parantèz

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anvan yon non varyab.

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Kòm yon egzanp, anvan nou te ekri int nan parantèz anvan nou

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flote x varyab.

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Nan fason sa a, nou jwenn nan valè a Int,

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twonke valè de 3.7 -

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3.

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Distribisyon enplisit, se lè du a otomatikman chanje

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kalite ki sanble ak yon kalite super, oswa fè kèk sòt lòt kote nan

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depoze san yo pa egzije itilizatè a ekri

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nenpòt kòd adisyonèl.

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Pou egzanp, lè nou ajoute 5 ak 1.1, valè nou deja gen

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kalite ki asosye ak yo.

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5 a se yon int, Lè nou konsidere ke 1.1 se yon flote.

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Yo nan lòd yo ajoute yo, òdinatè a projet 5 nan yon flote,

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ki ta kapab menm bagay la kòm ekri 5.0 nan la

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premye plas.

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Men, nan fason sa a nou di flote 5, oswa 5.0, plis sa ki te deja

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yon flote, 1.1, ak soti nan la nou ka aktyèlman ajoute sa yo

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valè epi pou yo jwenn valè a 6.1.

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Distribisyon enplisit tou pèmèt nou bay varyab la

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diferan kalite nan chak lòt.

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Nou ka toujou bay yon kalite mwens egzak nan yon pi plis

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egzak youn.

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Pou egzanp, si nou gen yon x doub, ak yon y Int -

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ak sa yo te kapab gen nenpòt ki valè ke nou fè yo al -

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nou ka di x egal y.

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Paske doub la gen presizyon plis pase yon int, konsa nou

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pa pral pèdi nenpòt enfòmasyon.

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Nan lòt men an, li pa ta nesesèman pi kòrèk yo di

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y egal x, paske doub la ta ka gen yon valè pi gwo pase

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nonb antye relatif la.

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Se konsa, nonm antye a pa ka kapab kenbe nan tout

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enfòmasyon ki estoke nan doub la.

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Se enplisit Distribisyon sèvi tou nan operatè konparezon tankou

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pi gran pase, mwens pase, oubyen operatè-a egalite.

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Nan fason sa nou ka di si 5.1 se pi gran pase 5 an, epi nou jwenn nan

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lakòz vre.

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Paske 5 se yon int, men li pral jete nan yon flote yo nan lòd yo

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dwe konpare ak flote nan 5.1, nou ta di 5.1 se

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pi gran pase 5.0.

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Menm a se laverite ak li di si 2.0 egal egal 2.

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Nou ta jwenn tou vre, paske òdinatè a ap lage a

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nonb antye relatif 2 a ap flote ak Lè sa a, di 2.0 egal egal 2.0,

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sa a se verite.

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pa bliye ke nou ka tou jete ant antye ak charaktèr,

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oswa valè ASCII.

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Charaktèr bezwen tou yo dwe redwi a binè, ki se poukisa ou

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ka byen fasil konvèti ant charaktèr ak rèspèktif yo

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Valè ASCII.

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Pou aprann plis sou sa a, tcheke deyò videyo nou an sou ASCII.

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Lè ou pran yon moman yo reflechi sou ki jan done a estoke,

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li kòmanse fè yon anpil nan sans.

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Li nan jis tankou diferans ki genyen ant van ak van.

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Done a se menm bagay la tou, men kalite a kapab chanje ki jan nou

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entèprete li.

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Non mwen se lòt bò larivyè Jouden Jozwiak, sa a cs50.