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[Powered by Google Translate] [Walkthrough - Tatizo Set 4]

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[Zamyla Chan - Chuo Kikuu cha Harvard]

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[Hii ni CS50. - CS50.TV]

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Wote haki. Hello, kila mtu, na kuwakaribisha kwa walkthrough 4.

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>> Leo pset yetu ni Forensics.

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Forensics ni pset kweli fun kwamba inahusisha kushughulika na files bitmap

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kugundua waliofanya uhalifu.

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Kisha tunakwenda resize files baadhi bitmap,

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basi tuko pia kwenda kukabiliana na sehemu ya kweli fun kuitwa Kuokoa,

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ambayo sisi ni kimsingi kukabidhiwa kadi ya kumbukumbu

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ambayo mtu ana ajali ilifutwa yote ya faili zao,

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na sisi ni aliuliza kuokoa files wale.

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>> Lakini kwanza, kabla ya sisi kupata katika pset, mimi kwa kweli nataka tu kumpongeza kila mtu.

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Sisi ni kuhusu saa midpoint ya kozi hii.

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Quiz 0 nyuma yetu, na sisi ni saa pset4, hivyo kimsingi, sisi ni nusu.

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Tumekuwa kuja njia ya muda mrefu kama wewe kuangalia nyuma psets yako, pset0 na pset1,

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hivyo kumpongeza mwenyewe juu ya kwamba,

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na sisi ni kwenda kupata katika baadhi ya mambo kweli fun.

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>> Hivyo toolbox yetu kwa pset hii, tena, badala ya mbio Sudo yum-y update,

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sisi ni uwezo wa kukimbia tu update50 kama wewe ni katika toleo 17.3 na juu ya appliance.

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Hivyo kuwa na uhakika ya kuendesha update50 - ni rahisi sana, wachache chini ya wahusika -

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kuhakikisha kwamba uko katika toleo la karibuni la appliance.

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Hasa ni muhimu update50 wakati sisi kuanza kutumia CS50 Check.

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Hivyo kuhakikisha kwamba kufanya hivyo.

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>> Kwa sehemu zote kwa pset hii,

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tunakwenda kuwa kushughulika na pembejeo faili na matokeo, faili I / O.

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Sisi ni kwenda kuwa kwenda juu ya mengi ya mipango ya kwamba kukabiliana na arrays

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akizungumzia files na mambo kama hayo,

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hivyo tunataka kuhakikisha kwamba sisi ni kweli familiar na starehe

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kushughulika na jinsi ya pembejeo na pato katika files.

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>> Katika code usambazaji kwa pset hii ni faili inayoitwa copy.c,

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na kwamba ni nini sisi ni kwenda kupata ni kwenda kuwa kweli muhimu kwetu

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kwa sababu tunakwenda kuishia kweli kuiga faili copy.c

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na tu Kubadili ni kidogo kuweza kufikia kwanza sehemu ya 2 ya kuweka tatizo.

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>> Na hivyo basi kama nilivyoeleza hapo awali, sisi ni kushughulika na bitmaps kama vile JPEGs.

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Hivyo kweli kuelewa muundo wa jinsi files wale ni kupangwa,

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jinsi gani tunaweza kweli kutafsiri sekunde 0 na 1s katika structs

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na mambo ambayo tunaweza kweli kuelewa na kutafsiri na kuhariri,

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kwamba itakuwa kweli muhimu,

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hivyo kwenda katika JPEG na files bitmap na kuelewa muundo wa wale.

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>> Pset4, kama kawaida, kuanza na sehemu ya maswali.

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Wale atapambana na faili I / O na wewe kupata accustomed kwamba.

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Kisha sehemu 1 ni Whodunit, ambayo wewe ni kupewa faili bitmap

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kwamba inaonekana kama aina ya dots nyekundu yote juu ya.

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Na kisha kimsingi nini sisi ni kwenda kufanya ni kuchukua faili hii na tu hariri ni kidogo

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katika toleo kwamba tunaweza kusoma.

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Kimsingi, mara sisi kumaliza, tutaweza kuwa na faili moja,

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ila tutaweza kuwa na uwezo wa kuona ujumbe siri siri kwa wale wote dots nyekundu.

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Kisha resize ni mpango kwamba, kutokana na faili

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na kisha kupewa jina la faili kwamba matokeo na kisha kupewa namba kama vile,

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mapenzi kweli resize kwamba bitmap na thamani kwamba integer.

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Kisha mwisho, tuna pset ya Kuokoa.

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Tumepewa kadi ya kumbukumbu na kisha kuwa na kupona zote za picha

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ambayo yamekuwa ajali imefutwa,

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lakini, kama tutaweza kujifunza, si kweli ilifutwa na kuondolewa kutoka faili;

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sisi tu aina ya waliopotea ambapo walikuwa katika faili, lakini sisi ni anaenda kuokoa kwamba.

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>> Mkuu. Hivyo kwenda katika faili I / O hasa, haya ni orodha nzima ya kazi ya kwamba wewe utakuwa kutumia.

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Tayari umeziona kidogo misingi ya fopen, fread, na fwrite,

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lakini sisi ni kwenda kuangalia zaidi katika baadhi ya faili I / O kazi kama vile fputc,

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ambayo wewe andika tu mhusika mmoja kwa wakati,

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kwa fseek, ambapo aina ya hoja nafasi faili kiashiria mbele na nyuma,

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na kisha baadhi ya watu wengine. Lakini tutaweza kwenda katika kwamba kidogo baadaye wakati pset.

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>> Hivyo kwanza, tu kupata ndani ya faili I / O kabla ya sisi kwenda katika pset,

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kufungua faili, kwa mfano, una nini cha kufanya ni kweli kuweka pointer faili hilo.

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Hivyo tuna * JALADA pointer.

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Katika kesi hiyo, mimi nina wito ni katika pointer sababu itakuja kuwa infile yangu.

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Na hivyo mimi nina kwenda kutumia fopen kazi na kisha jina la faili

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na kisha mode ambayo mimi nina kwenda kuwa kushughulika na faili.

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Hivyo kuna "r" katika kesi hii kwa kusoma, "w" kwa maandishi, na kisha "a" kwa appending.

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Kwa mfano, wakati wewe ni kushughulika na infile

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na wote unataka kufanya ni kusoma na bits ka kuhifadhiwa huko,

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basi pengine wewe kwenda kutaka kutumia "r" kama mode yako.

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Wakati unataka kweli kuandika, aina ya kufanya faili mpya,

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basi nini tunakwenda kufanya ni tunakwenda kufungua faili mpya

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na kutumia "w" mode kwa ajili ya kuandika.

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>> Hivyo basi wakati wewe ni kweli ya kusoma katika files, muundo ni kama ifuatavyo.

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Kwanza wewe ni pamoja pointer struct kwamba mapenzi yana ka kwamba wewe ni kusoma.

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Ili kwenda kuwa mahali mwisho ya ka kwamba wewe ni kusoma.

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Wewe kisha kwenda zinaonyesha ukubwa, kama kimsingi ngapi ka

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mpango wako ana kusoma katika na faili, ukubwa kimsingi moja kipengele ni,

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na kisha utaenda bayana jinsi wengi vipengele unataka kusoma.

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Na kisha hatimaye, una kujua ambapo wewe ni kusoma kutoka,

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ili kwenda kuwa pointer yako katika.

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Mimi rangi-coded haya kwa sababu fread pia ni sawa na fwrite,

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ila wewe unataka kuhakikisha kwamba matumizi ili haki,

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kuhakikisha kwamba wewe ni kweli kuandika au kusoma kutoka faili haki.

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>> Hivyo basi kama kabla, kama tuna kawaida ya kipengele kama vile idadi ya vipengele,

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basi tunaweza kucheza karibu hapa kidogo.

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Sema nina struct DOG na hivyo basi mimi nataka kusoma mbwa wawili kwa wakati.

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Nini mimi naweza kufanya ni kusema ukubwa wa kipengele moja ni kwenda kuwa ukubwa wa DOG moja

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na mimi naenda kwa kweli kusoma wawili.

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Vinginevyo, kitu ambacho ninaweza kufanya ni kusema mimi tu kwenda kusoma moja ya kipengele

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na kwamba moja ya kipengele ni kwenda kuwa ukubwa wa mbwa wawili.

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Basi hiyo ni sawa jinsi gani unaweza aina ya kucheza karibu na ukubwa na idadi

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kutegemea nini zaidi Intuitive na wewe.

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>> Wote haki. Hivyo sasa sisi kupata files kuandika.

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Wakati unataka kuandika kwenye faili, hoja ya kwanza ni kweli ambapo wewe ni kusoma kutoka.

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Basi hiyo ni kimsingi data kwamba wewe ni kwenda kuandika ndani ya faili,

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ambayo ni pointer nje mwishoni.

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Hivyo wakati wewe ni kushughulika na pset, kuhakikisha huna kupata kuchanganyikiwa.

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Labda kuwa na upande ufafanuzi kwa upande.

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Unaweza kuvuta ufafanuzi juu katika mwongozo na kuandika mtu na kisha fwrite, kwa mfano,

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katika terminal, au unaweza rejea nyuma kwenye slide huu

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na kuhakikisha kwamba unatumia moja ya haki.

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Hivyo tena, kwa fwrite, wakati una faili kwamba unataka kuandika katika,

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ambayo inaenda kuwa hoja ya mwisho na kwamba itakuja kuwa pointer faili hilo.

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Hivyo basi hiyo ni jinsi sisi kukabiliana na kuandika labda bytes kadhaa kwa wakati,

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lakini kusema unataka kuandika tu katika tabia tu mmoja.

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Kama tutaweza kuona baadaye katika mfano huu, katika bitmaps sisi itabidi kutumia.

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Kwamba wakati tunaweza kutumia fputc, kimsingi kuweka tu mhusika mmoja kwa wakati, CHR,

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ndani ya pointer faili, na kwamba ni wetu nje pointer huko.

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Hivyo basi popote kutafuta au kuandika kwenye faili,

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faili ni kuweka wimbo wa tulipo.

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Hivyo ni aina ya mshale, nafasi ya faili kiashiria.

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Na hivyo wakati sisi kuandika au kusoma tena ndani ya faili,

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faili kweli anakumbuka ambako ni,

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na hivyo anaendelea kutoka ambapo mshale ni.

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Hii inaweza kuwa ya manufaa wakati unataka, kusema, kusoma katika kiasi fulani kufanya kitu

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na kisha kusoma katika kiasi zifuatazo,

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lakini wakati mwingine sisi kutaka kurudi nyuma au kweli kuanza kutoka thamani fulani ya kumbukumbu.

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Hivyo basi kazi fseek, kile yake ni inaruhusu sisi hoja ya cursor katika faili fulani

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idadi fulani ya ka.

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Na kisha nini sisi kufanya ni bayana ambapo thamani ya kumbukumbu ni.

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Hivyo pengine ni hatua mbele au nyuma kutoka ambapo mshale sasa ni,

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au tunaweza bayana kwamba ni lazima tu hoja katika mwanzo wa faili

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au kutoka mwisho wa faili.

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Na hivyo unaweza kupita katika maadili hasi au chanya kwa kiasi,

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na kwamba itakuwa aina ya panya ama mbele au nyuma.

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>> Kabla ya sisi kupata katika psets mengine, maswali yoyote juu ya faili I / O?

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Sawa. Kama sisi kupata katika mifano zaidi, jisikie huru kunizuia kwa maswali.

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>> Hivyo katika Whodunit, wewe mitupu faili bitmap sawa na moja hii nyekundu kwenye slide,

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na inaonekana kama hii - rundo la dots nyekundu - na wewe kwa kweli sijui ni nini imeandikwa.

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Kama wewe kengeza, unaweza kuwa na uwezo wa kuona kidogo kibluu rangi ndani ya katikati.

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Kimsingi, hiyo ambapo Nakala inahifadhiwa.

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Kulikuwa na mauaji yaliyotokea, na tunahitaji kujua nani alifanya hivyo.

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Ili kufanya hivyo, tunahitaji aina ya kubadilisha picha hii katika format someka.

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Kama wewe guys milele wamekutana hii, wakati mwingine kutakuwa kidogo kits

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ambapo ingekuwa kioo wakimtukuza na filamu nyekundu. Mtu yeyote? Yeah.

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Hivyo itakuwa mitupu kitu kama hii, ungependa kuwa kioo wakimtukuza

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na filamu nyekundu juu yake, bila kuweka ni zaidi ya picha,

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na ungependa kuwa na uwezo wa kuona ujumbe siri humo.

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Hatuna kioo wakimtukuza na filamu nyekundu, hivyo badala tunakwenda aina ya kujenga yetu wenyewe

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katika pset hii.

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Na hivyo user ni kwenda pembejeo whodunit, basi kidokezo, bmp.,

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hivyo ndiyo infile, hiyo ni nyekundu dot ujumbe,

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na kisha wao ni kusema verdict.bmp ni kwenda kuwa outfile yetu.

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Hivyo ni kwenda kujenga mpya bitmap sanamu sawa na kidokezo moja

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isipokuwa katika format someka ambapo tunaweza kuona ujumbe siri.

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>> Tangu sisi ni kwenda kuwa kushughulika na editing na manipulating bitmaps ya aina fulani,

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tunakwenda aina ya kupiga mbizi katika ndani ya muundo wa files haya bitmap.

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Sisi akaenda juu kidogo kidogo haya katika hotuba, lakini hebu tuangalie katika wao baadhi zaidi.

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Bitmaps kimsingi tu mpangilio wa ka

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ambapo tumekuwa maalum ambayo ka maana gani.

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Hivyo hapa ni aina ya kama ramani ya picha bitmap

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akisema kwamba huanza na baadhi ya faili header, huanza na baadhi ya taarifa katika huko.

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Unaweza kuona kwamba katika idadi kuhusu Byte 14 ukubwa wa picha unahitajika bitmap,

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na inaendelea.

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Lakini basi nini tuko kweli nia hapa ni kuanzia karibu idadi Byte 54.

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Tuna triples haya RGB.

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Nini kwamba kinaendelea kufanya ni vyenye saizi halisi, maadili rangi.

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Kila kitu juu ya kwamba katika header ni baadhi ya habari

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sambamba na ukubwa wa picha, upana wa sanamu, na urefu.

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Wakati sisi kwenda katika padding baadaye, tutaweza kuona nini ukubwa wa picha

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inaweza kuwa tofauti kuliko upana au urefu.

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Hivyo basi kuwakilisha hizi - picha hizo bitmap ni Mwandamano ya ka -

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nini tunaweza kufanya ni kusema sawa, mimi naenda kukumbuka kwamba katika index 14,

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hiyo ambapo kawaida ni, kwa mfano, lakini badala yake nini tunakwenda kufanya ili kufanya hii rahisi

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ni kurejelea katika struct.

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Na hivyo tuna structs mbili kwa ajili yetu, BITMAPFILEHEADER

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na BITMAPINFOHEADER,

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na hivyo wakati tunasoma katika faili la kwamba, kwa default itakavyo kuwa kwenda katika utaratibu,

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na hivyo ili ni pia kwenda kujaza katika ndani ya vigezo kama vile biWidth na biSize.

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Na kisha hatimaye, pixel kila ni kuwakilishwa na ka tatu.

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moja ya kwanza ni ya kiasi cha bluu katika pixel, ya pili ni ya kiasi cha kijani,

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na hatimaye, kiasi ya nyekundu, ambapo 0 ni kimsingi hakuna kijani bluu au hakuna au hakuna nyekundu

176
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na kisha ff ni thamani upeo.

177
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Hizi ni hexadesimoli maadili.

178
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Hivyo basi kama tuna ff0000, basi kwamba sambamba na kiasi cha juu cha bluu

179
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na kisha hakuna kijani na hakuna nyekundu, hivyo basi kwamba atatupa pixel bluu.

180
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Kisha kama tuna ff yote ya hela bodi, basi hiyo ina maana kwamba tuna pixel nyeupe.

181
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Hii ni aina ya kinyume na kawaida wakati sisi kusema RGB. Ni kweli kwenda BGR.

182
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>> Hivyo kama sisi kweli kuangalia katika mfano wa sanamu bitmap - ngoja nikuondoe moja hapa.

183
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Ni kidogo kidogo.

184
00:13:39,890 --> 00:13:47,840
Mimi nina zooming katika, na tunaweza kuona ni pixelated. Inaonekana kama vitalu wa rangi.

185
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Una vitalu nyeupe na kisha nyekundu vitalu.

186
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Kama wewe kucheza katika Paint Microsoft, kwa mfano, unaweza kufanya kitu kama hicho

187
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na kimsingi tu uchoraji mraba fulani ili maalum.

188
00:13:58,960 --> 00:14:08,060
Hivyo basi nini hii inasababisha na katika bitmap ni kama ifuatavyo.

189
00:14:08,060 --> 00:14:15,710
Hapa tuna saizi ya kwanza nyeupe, kwamba wote ni f 6, na kisha tuna saizi nyekundu,

190
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unahitajika kwa 0000ff.

191
00:14:19,910 --> 00:14:27,940
Na hivyo mlolongo wa bytes kwamba tuna inaonyesha jinsi picha bitmap ni kwenda kuangalia.

192
00:14:27,940 --> 00:14:32,230
Hivyo kile nimepata kufanyika hapa ni tu imeandikwa nje wale ka wote na kisha rangi nyekundu katika

193
00:14:32,230 --> 00:14:37,550
ili uweze aina ya kuona, kama wewe squint kidogo, jinsi ya aina hiyo inaonyesha uso smiley.

194
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>> njia ambayo bitmap images kazi ni mimi wanaangalia ni kimsingi kama gridi ya taifa.

195
00:14:46,390 --> 00:14:54,940
Na hivyo kwa default, kila mstari wa gridi ina kuwa nyingi ya ka 4.

196
00:15:00,520 --> 00:15:07,060
Kama sisi kuangalia picha bitmap, wewe ni kujaza thamani kila.

197
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Kwa mfano, unaweza kuwa nyekundu hapa, kijani hapa, bluu hapa,

198
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lakini wewe kuwa na kuhakikisha kwamba picha ni kujazwa na majina tofauti ya ka nne.

199
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Hivyo kama nataka picha yangu kuwa tatu vitalu pana, basi mimi ingekuwa kuweka thamani tupu

200
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katika moja ya mwisho ya kufanya hivyo nyingi ya nne.

201
00:15:35,640 --> 00:15:39,530
Hivyo basi napenda kuongeza katika kitu ambacho sisi ni wito padding.

202
00:15:39,530 --> 00:15:43,750
Mimi tu anaenda zinaonyesha kuwa kuna na x.

203
00:15:44,920 --> 00:15:54,160
Sasa wanasema tunataka picha kwamba ni 7 saizi ya muda mrefu, kwa mfano.

204
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Tuna 1, 2, 3, 4, 5, 6, 7,

205
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na yote ya kwamba ni kujazwa na Michezo katika.

206
00:16:07,000 --> 00:16:10,620
njia ambayo images bitmap kazi ni kwamba tunahitaji 8.

207
00:16:10,620 --> 00:16:12,460
Hivi sasa tuna 1, 2, 3, 4, 5, 6, 7.

208
00:16:12,460 --> 00:16:19,360
Tunahitaji 8 mazingira kwa ajili ya picha bitmap ya kusoma kwa usahihi.

209
00:16:19,360 --> 00:16:25,600
Hivyo basi nini sisi kufanya ni kuongeza katika kidogo tu ya padding

210
00:16:25,600 --> 00:16:29,430
kuhakikisha kwamba wote wa widths ni sare

211
00:16:29,430 --> 00:16:34,260
na kwamba wote wa widths ni nyingi ya 4.

212
00:16:42,110 --> 00:16:47,310
Na hivyo mimi awali zilionyesha, padding kama x au squiggly line,

213
00:16:47,310 --> 00:16:53,880
lakini katika picha halisi bitmap padding ni unahitajika kwa 0 hexadesimoli.

214
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Hivyo kwamba itakuwa tabia moja, 0.

215
00:16:58,980 --> 00:17:06,329
Nini kinaweza kuja Handy ni amri xxd.

216
00:17:06,329 --> 00:17:11,220
Kile yake ni kweli inaonyesha wewe, like sawa na nini mimi kabla na smiley

217
00:17:11,220 --> 00:17:15,630
wakati mimi kwa kweli kuchapishwa nini rangi ya kila itakuwa kwa pixel

218
00:17:15,630 --> 00:17:21,800
na kisha rangi-coded hivyo, wakati kukimbia xxd na amri zifuatazo,

219
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basi itakuwa kweli magazeti nje nini rangi ni kwa wale saizi.

220
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Nini wewe kufanya ni zaidi ya hapa mimi zinaonyesha, kama s-54

221
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anasema kuwa mimi naenda kuanza saa Byte 54

222
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kwa sababu kabla ya hapo, kumbuka kama sisi kuangalia nyuma na ramani ya bitmaps,

223
00:17:40,820 --> 00:17:42,690
kwamba taarifa zote header na mambo kama hayo.

224
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Lakini nini sisi kweli huduma kuhusu ni saizi halisi kwamba zinaonyesha rangi.

225
00:17:46,280 --> 00:17:52,700
Hiyo na kuongeza kwamba katika bendera,-s 54, basi sisi ni uwezo wa kuona maadili rangi.

226
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Na msiwe na wasiwasi juu bendera ngumu na mambo kama hayo.

227
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Katika spec kuweka tatizo, itabidi maelekezo ya jinsi ya kutumia xxd kuonyesha Ukubwa.

228
00:18:07,070 --> 00:18:15,590
Hivyo kama unaweza kuona hapa, ni aina ya inaonekana kama sanduku kijani, hii kitu kidogo.

229
00:18:15,590 --> 00:18:23,610
Nimekuwa rangi-coded 00ff00 kama kimsingi akisema hakuna bluu, mengi ya kijani, na hakuna nyekundu.

230
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Hivyo kwamba sambamba na kijani.

231
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Kama unaweza kuona hapa, tunaona Mstatili kijani.

232
00:18:31,920 --> 00:18:36,660
This Mstatili kijani ni 3 tu saizi mbalimbali, hivyo basi kile sisi kufanya

233
00:18:36,660 --> 00:18:44,350
kuhakikisha kwamba picha ni nyingi ya 4 ni mpana kuongeza katika padding ziada.

234
00:18:44,350 --> 00:18:49,460
Na hivyo basi hiyo ni jinsi ya kuona haya sekunde 0 hapa.

235
00:18:49,460 --> 00:18:54,510
Hii kweli kuwa matokeo ya resize pset yako,

236
00:18:54,510 --> 00:19:01,350
kimsingi kuchukua bitmap ndogo na kisha handla hivyo kwa 4.

237
00:19:01,350 --> 00:19:09,380
Na hivyo kile sisi kuona ni kwamba kweli picha hii ni 12 × pana, lakini 12 ni nyingi ya 4,

238
00:19:09,380 --> 00:19:12,940
na hivyo sisi kweli sioni sekunde 0 mwishoni kwa sababu hatuna haja ya kuongeza yoyote

239
00:19:12,940 --> 00:19:19,070
sababu ni kikamilifu padded. Haina lolote zaidi ya chumba.

240
00:19:20,720 --> 00:19:23,470
>> Sawa. Maswali yoyote kuhusu padding?

241
00:19:25,150 --> 00:19:27,460
Sawa. Cool.

242
00:19:27,460 --> 00:19:32,520
>> Kama nilivyoeleza hapo awali, bitmaps ni tu mlolongo wa bytes.

243
00:19:32,520 --> 00:19:39,170
Na hivyo kile sisi ni badala ya wanaohitaji kwa kuweka wimbo wa idadi hasa ambayo ya Byte

244
00:19:39,170 --> 00:19:47,050
sambamba na kipengele maalum, sisi kweli tumemuumba struct kuwakilisha kwamba.

245
00:19:47,050 --> 00:19:50,930
Hivyo kile sisi ni struct RGBTRIPLE.

246
00:19:50,930 --> 00:19:54,590
Wakati wowote na mfano wa triple RGB,

247
00:19:54,590 --> 00:20:00,970
kwa sababu hii ni aina define struct, basi unaweza kupata variable rgbtBlue,

248
00:20:00,970 --> 00:20:09,520
vile vile vigezo Green na Red, ambayo yanaonyesha jinsi gani buluu, kijani, na nyekundu,

249
00:20:09,520 --> 00:20:11,580
mtiririko huo, una.

250
00:20:11,580 --> 00:20:16,800
>> Hivyo kama tuna bluu variable kuweka 0, seti ya kijani na ff,

251
00:20:16,800 --> 00:20:22,060
ambayo ni thamani ya kiwango cha unaweza kuwa, na kisha variable nyekundu kuweka 0,

252
00:20:22,060 --> 00:20:27,870
basi ingekuwa nini rangi maalum huu RGB triple kuwakilisha? >> [Mwanafunzi] Green.

253
00:20:27,870 --> 00:20:29,150
Green. Hasa.

254
00:20:29,150 --> 00:20:34,480
Ni kwenda kuwa na manufaa kwa kujua kwamba wakati wowote una mfano wa triple RGB,

255
00:20:34,480 --> 00:20:41,340
unaweza kweli kupata kiasi cha Michezo - buluu, kijani, na nyekundu - tofauti.

256
00:20:43,350 --> 00:20:54,900
>> Sasa kwa kuwa tumekuwa aliyesema kuhusu muundo wa kwamba, hebu kuchukua kuangalia faili BMP.

257
00:20:54,900 --> 00:20:57,870
Hizi ni structs alifanya kwa ajili yenu.

258
00:20:57,870 --> 00:21:01,820
Hapa tuna struct BITMAPFILEHEADER.

259
00:21:01,820 --> 00:21:07,610
Wa maslahi ni kawaida.

260
00:21:07,610 --> 00:21:12,660
Baadaye, tuna header info, ambayo ina wachache na mambo zaidi ya kuwa ni ya kuvutia kwa sisi,

261
00:21:12,660 --> 00:21:15,480
yaani ukubwa, upana, na urefu.

262
00:21:15,480 --> 00:21:19,170
Kama tutaweza kuingia katika baadaye, wakati wewe kusoma katika na faili,

263
00:21:19,170 --> 00:21:25,500
ni moja kwa moja anasoma katika sababu tumekuwa kuweka ili kuwa sawa.

264
00:21:25,500 --> 00:21:31,990
Hivyo biSize yana ka haki kwamba yanahusiana na ukubwa halisi wa picha.

265
00:21:34,700 --> 00:21:40,500
Na kisha hapa, mwisho, kama tumekuwa kuongelea, tuna RGBTRIPLE typedef struct.

266
00:21:40,500 --> 00:21:46,840
Tuna rgbtBlue, Green, na Red yanayohusiana na hayo.

267
00:21:48,210 --> 00:21:49,340
>> Mkuu. Sawa.

268
00:21:49,340 --> 00:21:56,360
Sasa kwa kuwa tunaelewa bitmaps kidogo, kuelewa kwamba tuna header faili

269
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na header info yanayohusiana na hayo na kisha baada ya sisi kuwa na mambo ya kuvutia

270
00:22:00,790 --> 00:22:05,110
ya rangi, na rangi hizo ni kuwakilishwa na structs RGBTRIPLE,

271
00:22:05,110 --> 00:22:12,710
na wale, kwa upande mwingine, kuwa na maadili tatu zinazohusika na bluu, kijani, na nyekundu.

272
00:22:12,710 --> 00:22:17,270
>> Hivyo sasa, tunaweza kufikiri kuhusu aina ya Kuokoa kidogo.

273
00:22:17,270 --> 00:22:20,130
Sorry. Fikiria kuhusu Whodunit.

274
00:22:20,130 --> 00:22:25,750
Wakati sisi kuwa kidokezo yetu ya SVG, basi ni nini tunataka kufanya ni kusoma katika hilo pixel kwa pixel

275
00:22:25,750 --> 00:22:33,860
na kisha kubadili namna fulani saizi wale ili tuweze pato ndani format someka.

276
00:22:33,860 --> 00:22:41,020
Na hivyo kwa pato hilo, sisi ni kwenda kuandika pixel kwa pixel katika faili verdict.bmp.

277
00:22:41,020 --> 00:22:45,120
Hiyo ni aina ya mengi ya kufanya. Tunatambua kwamba.

278
00:22:45,120 --> 00:22:49,860
Hivyo kile ambacho tumefanya ni kweli tumekuwa zinazotolewa kwa copy.c.

279
00:22:49,860 --> 00:22:57,610
Nini copy.c gani ni tu hufanya nakala halisi ya faili aliyopewa bitmap na kisha matokeo yake.

280
00:22:57,610 --> 00:23:01,900
Hivyo hii tayari kufungua faili kwa ajili yenu, wasomaji katika pixel kwa pixel,

281
00:23:01,900 --> 00:23:04,510
na kisha anaandika katika ndani ya faili pato.

282
00:23:04,510 --> 00:23:07,080
>> Hebu tuangalie kwamba.

283
00:23:13,390 --> 00:23:18,290
Hii ni kuhakikisha matumizi sahihi,

284
00:23:18,290 --> 00:23:22,640
kupata filenames hapa.

285
00:23:22,640 --> 00:23:29,940
Nini hii unaweka faili pembejeo kuwa kile ambacho tumekuwa kupita katika katika infile hapa,

286
00:23:29,940 --> 00:23:34,750
ambayo ni amri ya mstari wa pili yetu hoja.

287
00:23:34,750 --> 00:23:37,640
Hundi ya kuhakikisha kwamba tunaweza kufungua faili.

288
00:23:38,960 --> 00:23:44,860
Hundi ya kuhakikisha tunaweza kufanya outfile mpya hapa.

289
00:23:45,630 --> 00:23:53,270
Kisha nini hii haina hapa, ni tu kimsingi kuanza kusoma katika faili la bitmap tangu mwanzo.

290
00:23:53,270 --> 00:23:56,700
mwanzo, kama tujuavyo, ina BITMAPFILEHEADER,

291
00:23:56,700 --> 00:24:03,200
na hivyo wale Mwandamano wa bits itakuwa moja kwa moja kujaza BITMAPFILEHEADER.

292
00:24:03,200 --> 00:24:07,940
Hivyo nini sisi hapa ni kusema kwamba bf BITMAPFILEHEADER -

293
00:24:07,940 --> 00:24:13,150
hiyo ni variable wetu mpya wa BITMAPFILEHEADER aina -

294
00:24:13,150 --> 00:24:22,560
sisi ni kwenda kuweka ndani ya bf nini sisi kusoma kutoka katika pointer, ambayo ni infile yetu.

295
00:24:22,560 --> 00:24:23,970
Kiasi gani sisi kusoma?

296
00:24:23,970 --> 00:24:32,160
Tunasoma katika ngapi ka tunahitaji vyenye BITMAPFILEHEADER nzima.

297
00:24:32,160 --> 00:24:34,660
Vile vile, kwamba ni nini tunaweza kufanya kwa ajili header info.

298
00:24:34,660 --> 00:24:39,010
Hivyo sisi ni kuendelea pamoja faili wetu katika infile,

299
00:24:39,010 --> 00:24:44,360
na sisi ni kusoma bits wale na ka, na sisi ni plugging yao moja kwa moja katika

300
00:24:44,360 --> 00:24:47,880
katika haya matukio ya vigezo kwamba sisi ni maamuzi.

301
00:24:49,370 --> 00:24:53,800
Hapa tuko tu kuhakikisha kuwa bitmap ni bitmap.

302
00:24:57,670 --> 00:25:01,030
>> Sasa tuna outfile, haki?

303
00:25:01,030 --> 00:25:04,420
Hivyo kama ulivyo wakati sisi kujenga hilo, ni kimsingi tupu.

304
00:25:04,420 --> 00:25:07,710
Hivyo inabidi kimsingi kuunda bitmap mpya kutoka mwanzo.

305
00:25:07,710 --> 00:25:12,280
Tunachofanya ni sisi kuhakikisha kwamba sisi nakala katika header faili

306
00:25:12,280 --> 00:25:16,850
na header info tu kama infile ana.

307
00:25:16,850 --> 00:25:22,850
Tunachofanya ni sisi kuandika - na kukumbuka kwamba bf ni variable

308
00:25:22,850 --> 00:25:29,300
ya BITMAPFILEHEADER aina, ili kile sisi kufanya ni sisi tu kutumia kwamba maudhui

309
00:25:29,300 --> 00:25:34,980
kuandika katika outfile.

310
00:25:36,550 --> 00:25:38,510
Hapa, kumbuka kuongelea padding,

311
00:25:38,510 --> 00:25:47,820
jinsi ni muhimu ili kuhakikisha kuwa kiasi ya saizi ya kwamba sisi ni nyingi ya 4.

312
00:25:47,820 --> 00:25:52,790
Hii ni formula pretty manufaa kwa mahesabu ni kiasi gani padding una

313
00:25:52,790 --> 00:25:57,670
aliyopewa upana wa faili yako.

314
00:25:57,670 --> 00:26:04,120
Mimi nataka wewe guys kukumbuka kwamba katika copy.c tuna formula kwa ajili ya kuhesabu padding.

315
00:26:04,120 --> 00:26:07,970
Sawa? Hivyo kila mtu kukumbuka kwamba. Mkuu.

316
00:26:07,970 --> 00:26:14,050
Hivyo basi nini copy.c gani ijayo ni iterates juu ya yote ya scanlines.

317
00:26:14,050 --> 00:26:23,730
Ni inakwenda kupitia safu ya kwanza na kisha maduka kila mara tatu kwamba wasomaji

318
00:26:23,730 --> 00:26:26,920
na kisha anaandika ndani outfile.

319
00:26:26,920 --> 00:26:33,120
Hivyo basi hapa sisi ni kusoma tu moja RGB triple wakati

320
00:26:33,120 --> 00:26:39,860
na kisha kuweka triple huo katika outfile.

321
00:26:41,120 --> 00:26:48,340
sehemu Tricky ni kwamba padding si triple RGB,

322
00:26:48,340 --> 00:26:55,200
na hivyo hatuwezi kusoma tu kwamba kiasi padding ya triples RGB.

323
00:26:55,200 --> 00:27:01,460
Tunachotakiwa kufanya ni kweli tu hoja faili wetu nafasi kiashiria, hoja ya cursor yetu,

324
00:27:01,460 --> 00:27:06,840
kwa aina ya ruka juu ya padding yote ili sisi ni saa mstari unaofuata.

325
00:27:06,840 --> 00:27:12,990
Na kisha nini hii haina ni nakala inaonyesha jinsi unaweza kutaka kuongeza padding.

326
00:27:12,990 --> 00:27:14,990
Hivyo tumekuwa mahesabu kiasi gani padding tunahitaji,

327
00:27:14,990 --> 00:27:18,220
hivyo kwamba ina maana kuwa tunahitaji padding idadi ya sekunde 0.

328
00:27:18,220 --> 00:27:24,510
Nini hii ni kwa kitanzi kwamba unaweka padding idadi ya sekunde 0 ndani ya outfile yetu.

329
00:27:24,510 --> 00:27:31,170
Na kisha hatimaye, wewe karibu files wote. Wewe karibu infile kama vile outfile.

330
00:27:31,170 --> 00:27:34,870
>> Basi hiyo ni jinsi copy.c matendo,

331
00:27:34,870 --> 00:27:37,430
na kwamba kinaendelea kuwa pretty muhimu.

332
00:27:39,720 --> 00:27:43,750
Badala ya moja kwa moja tu kwa kweli kuiga na pasting ni

333
00:27:43,750 --> 00:27:46,800
au tu kuangalia ni na kuandika katika chochote unataka,

334
00:27:46,800 --> 00:27:49,440
unaweza tu wanataka nitafanya amri hii katika terminal,

335
00:27:49,440 --> 00:27:54,520
linganisha copy.c whodunit.c, ambayo itakuwa kuunda faili mpya, whodunit.c,

336
00:27:54,520 --> 00:27:58,330
kwamba ina exact maudhui kama nakala gani.

337
00:27:58,330 --> 00:28:03,880
Hivyo basi nini tunaweza kufanya ni kutumia kama mfumo wa juu ambayo kujenga na kuhariri

338
00:28:03,880 --> 00:28:06,900
kwa whodunit faili wetu.

339
00:28:08,500 --> 00:28:14,670
>> Hizi ni yetu-dos kufanya kwa Whodunit, lakini kile copy.c gani

340
00:28:14,670 --> 00:28:16,730
ni kweli inachukua huduma ya wengi wao kwa ajili yetu.

341
00:28:16,730 --> 00:28:21,900
Basi wote tunahitaji kufanya ijayo ni kubadilisha saizi kama inahitajika

342
00:28:21,900 --> 00:28:25,920
kwa kweli kufanya faili someka.

343
00:28:25,920 --> 00:28:32,960
Kumbuka kwamba kwa pixel aliyopewa tatu, hivyo kwa variable fulani ya RGBTRIPLE aina,

344
00:28:32,960 --> 00:28:35,990
unaweza kupata bluu, maadili ya kijani, na nyekundu.

345
00:28:35,990 --> 00:28:38,670
Hiyo atakuja katika Handy kwa sababu kama unaweza kupata yao,

346
00:28:38,670 --> 00:28:41,770
hiyo ina maana kwamba unaweza pia kuangalia yao,

347
00:28:41,770 --> 00:28:45,430
na hiyo ina maana kwamba unaweza pia mabadiliko yao.

348
00:28:45,430 --> 00:28:49,430
>> Hivyo wakati sisi kurudi mfano wetu nyekundu magnifying kioo,

349
00:28:49,430 --> 00:28:53,390
kimsingi, kwamba alikuwa kaimu kama aina ya chujio kwa ajili yetu.

350
00:28:53,390 --> 00:28:58,160
Basi nini tunataka kufanya ni tunataka kuchuja wote wa triples zinazokuja in

351
00:28:58,160 --> 00:29:01,240
Kuna njia mbalimbali za kufanya hivi.

352
00:29:01,240 --> 00:29:07,100
Kimsingi, unaweza kuwa na kila aina ya chujio unataka.

353
00:29:07,100 --> 00:29:09,890
Labda unataka kubadilisha saizi wote nyekundu

354
00:29:09,890 --> 00:29:13,570
au labda unataka kubadilisha rangi tofauti pixel kwa rangi tofauti.

355
00:29:13,570 --> 00:29:15,400
Hiyo ni juu yako.

356
00:29:15,400 --> 00:29:19,580
Kumbuka kwamba unaweza kuangalia nini rangi pixel ni

357
00:29:19,580 --> 00:29:23,000
na kisha unaweza pia mabadiliko hayo kama wewe ni kwenda kupitia.

358
00:29:24,410 --> 00:29:26,420
>> Sawa. Basi hiyo ni Whodunit.

359
00:29:26,420 --> 00:29:32,760
Mara baada ya kukimbia Whodunit, utajua ambao culprit ya uhalifu ilikuwa.

360
00:29:32,760 --> 00:29:35,540
>> Sasa tunakwenda kwenda Resize.

361
00:29:35,540 --> 00:29:37,990
Sisi ni kwenda bado kuwa kushughulika na bitmaps.

362
00:29:37,990 --> 00:29:40,750
Nini sisi ni kwenda kufanya ni sisi itawabidi bitmap pembejeo

363
00:29:40,750 --> 00:29:45,890
na kisha tunakwenda kupita katika idadi na kisha kupata bitmap outfile

364
00:29:45,890 --> 00:29:51,380
ambapo kwamba kimsingi infile yetu kuongezwa kwa n.

365
00:29:54,670 --> 00:30:01,450
Sema faili yangu ilikuwa moja tu pixel kubwa.

366
00:30:01,450 --> 00:30:09,100
Kisha kama n yangu ilikuwa 3, scaling na 3, basi napenda kurudia kwamba pixel n idadi ya nyakati,

367
00:30:09,100 --> 00:30:14,410
hivyo mara 3, na kisha pia kuongeza ni chini mara 3 pia.

368
00:30:14,410 --> 00:30:17,840
Hivyo unaweza kuona mimi nina kuongeza kwa wima pamoja na usawa.

369
00:30:17,840 --> 00:30:19,680
>> Na kisha hapa ni mfano.

370
00:30:19,680 --> 00:30:27,590
Kama una n = 2, unaweza kuona kwamba kwanza pixel bluu kuna alirudia mara mbili

371
00:30:27,590 --> 00:30:30,930
usawa kama vizuri kama mara mbili wima.

372
00:30:30,930 --> 00:30:38,040
Na kisha kuwa inaendelea, na hivyo kuwa na kuongeza moja kwa moja ya picha yako ya awali na mbili.

373
00:30:40,920 --> 00:30:47,600
>> Hivyo basi kama tulikuwa na undani pseudocode kwa hili, tunataka kufungua faili.

374
00:30:47,600 --> 00:30:49,880
Na kisha kujua kwamba kama sisi kurudi nyuma hapa,

375
00:30:49,880 --> 00:30:54,540
tunaona kwamba upana kwa outfile kinaenda kuwa tofauti kuliko upana kwa infile.

376
00:30:54,540 --> 00:30:56,130
Hiyo ina maana gani?

377
00:30:56,130 --> 00:31:01,230
Hiyo ina maana kwamba header yetu habari ni kwenda na mabadiliko.

378
00:31:01,230 --> 00:31:03,790
Na hivyo kile tutaweza wanataka kufanya ni update info header,

379
00:31:03,790 --> 00:31:11,820
kujua kwamba wakati tunasoma katika files kama wewe ni uendeshaji juu ya mfumo copy.c,

380
00:31:11,820 --> 00:31:17,570
tayari tuna variable kwamba inaonyesha kile kawaida ni na mambo kama hayo.

381
00:31:17,570 --> 00:31:24,060
Hivyo mara tu una kwamba, nini unaweza kutaka kufanya mabadiliko vigezo wale fulani.

382
00:31:24,060 --> 00:31:29,380
Kumbuka, kama una struct, jinsi wewe kupata vigezo ndani ya kwamba.

383
00:31:29,380 --> 00:31:32,080
Wewe kutumia operator dot, haki?

384
00:31:32,080 --> 00:31:36,420
Hivyo basi kwa kutumia kwamba, unajua kwamba utasikia haja ya kubadili info header.

385
00:31:36,480 --> 00:31:41,030
Hivyo hapa ni tu orodha ya mambo ya halisi kwamba ni kwenda kuwa kubadilisha katika faili yako.

386
00:31:41,030 --> 00:31:45,180
ukubwa wa faili inaenda kubadilika, picha, kama vile upana na urefu.

387
00:31:45,180 --> 00:31:50,080
Hivyo basi kurejea ramani ya bitmaps,

388
00:31:50,080 --> 00:31:57,730
kuangalia kama ni header faili au header info kwamba ina taarifa kwamba

389
00:31:57,730 --> 00:32:00,920
na basi mabadiliko kama inahitajika.

390
00:32:05,010 --> 00:32:12,470
Tena, wanasema linganisha copy.c resize.c.

391
00:32:12,470 --> 00:32:19,270
Hiyo ina maana kwamba resize.c sasa ina kila kitu ambacho zilizomo ndani ya nakala

392
00:32:19,270 --> 00:32:24,490
kwa sababu nakala hutoa sisi njia ya kusoma katika kila pixel scanline kwa pixel.

393
00:32:24,490 --> 00:32:29,860
Ila sasa, badala ya kubadilisha maadili kama tulivyofanya katika Whodunit,

394
00:32:29,860 --> 00:32:37,980
nini tunataka kufanya ni sisi unataka kuandika katika saizi nyingi

395
00:32:37,980 --> 00:32:43,580
muda mrefu kama n wetu ni mkubwa kuliko 1.

396
00:32:43,580 --> 00:32:47,110
>> Kisha nini tunataka kufanya ni tunataka kunyoosha kwa usawa na n,

397
00:32:47,110 --> 00:32:50,490
kama vile kunyoosha kwa wima na n.

398
00:32:50,490 --> 00:32:52,710
Jinsi gani tunafanya hivi?

399
00:32:52,710 --> 00:32:56,890
Sema n yako ni 2 na una hii infile aliyopewa.

400
00:32:56,890 --> 00:32:58,730
Cursor yako ni kwenda kuanza saa moja ya kwanza,

401
00:32:58,730 --> 00:33:03,530
na nini unataka kufanya kama n ni 2, unataka magazeti katika 2 wa wale.

402
00:33:03,530 --> 00:33:05,490
Hivyo magazeti katika 2 wa wale.

403
00:33:05,490 --> 00:33:10,830
Kisha mshale wako ni kwenda hoja kwa pixel pili, ambayo ni moja nyekundu,

404
00:33:10,830 --> 00:33:18,400
na ni kwenda magazeti nje ya 2 ndio wale nyekundu, appending ni kwenye nini ni kufanyika kabla.

405
00:33:18,400 --> 00:33:26,280
Kisha mshale itahamia kwa pixel ijayo na kusogea katika 2 wa wale.

406
00:33:26,280 --> 00:33:37,180
Kama kuangalia nyuma kwa mfumo copy.c, nini hii haina haki hapa

407
00:33:37,180 --> 00:33:42,830
ni inajenga mfano mpya wa triple RGB, variable mpya iitwayo tatu.

408
00:33:42,830 --> 00:33:50,500
Na hapa wakati anasoma ndani yake, inasomeka kutoka infile 1 RGBTRIPLE

409
00:33:50,500 --> 00:33:53,470
na maduka ya kuwa ndani ya variable kwamba tatu.

410
00:33:53,470 --> 00:33:57,590
Hivyo basi wewe kweli kuwa kutofautiana anayewakilisha kwamba pixel fulani.

411
00:33:57,590 --> 00:34:05,290
Kisha wakati kuandika, nini unaweza kutaka kufanya ni encase kauli fwrite katika kwa kitanzi

412
00:34:05,290 --> 00:34:11,080
kwamba anaandika ndani outfile yako kama mara nyingi kama inahitajika.

413
00:34:17,449 --> 00:34:20,100
Hiyo ni rahisi ya kutosha.

414
00:34:20,200 --> 00:34:27,590
Tu kimsingi kurudia mchakato wa kuandika n idadi ya mara ya kuongeza kwa usawa.

415
00:34:27,590 --> 00:34:32,969
>> Lakini basi tunahitaji kukumbuka kwamba padding yetu ni kwenda na mabadiliko.

416
00:34:47,350 --> 00:34:53,020
Hapo awali, wanasema sisi na kitu fulani cha urefu 3.

417
00:34:53,020 --> 00:35:00,130
Basi tunataka kuongeza tu katika kiasi gani padding? Moja tu zaidi ya kufanya hivyo nyingi ya 4.

418
00:35:00,130 --> 00:35:10,480
Lakini kusema sisi ni kuongeza picha hii hasa kwa n = 2.

419
00:35:10,480 --> 00:35:16,300
Hivyo basi, jinsi wengi blue saizi ingekuwa tuna mwishoni? Tunataka kuwa na 6.

420
00:35:16,300 --> 00:35:21,470
1, 2, 3, 4, 5, 6. Wote haki.

421
00:35:21,470 --> 00:35:26,580
6 si nyingi ya 4. Nini nyingi karibu ya 4? Hiyo itakuwa 8.

422
00:35:26,580 --> 00:35:33,200
Hivyo sisi ni kweli kwenda na wahusika 2 padding huko.

423
00:35:33,200 --> 00:35:38,720
>> Je, mtu yeyote kumbuka kama tuna formula kwa mahesabu ya padding

424
00:35:38,720 --> 00:35:41,350
na ambapo ambayo inaweza kuwa?

425
00:35:41,350 --> 00:35:45,160
[Inaudible mwanafunzi majibu] >> Yeah, copy.c. Haki.

426
00:35:45,160 --> 00:35:49,800
Kuna formula katika copy.c kwa mahesabu ni kiasi gani padding una

427
00:35:49,800 --> 00:35:53,810
aliyopewa upana fulani ya sanamu bitmap.

428
00:35:53,810 --> 00:36:02,950
Hivyo basi, kwamba kinaendelea kuwa na manufaa wakati unahitaji kuongeza kwa kiasi fulani ya padding

429
00:36:02,950 --> 00:36:06,160
kwa kweli takwimu nje kiasi gani padding unahitaji kuongeza.

430
00:36:10,820 --> 00:36:15,850
Lakini moja kumbuka, ingawa, ni kwamba wewe unataka kuhakikisha kwamba unatumia haki ya kawaida.

431
00:36:15,850 --> 00:36:21,410
Kuwa makini tu kwa sababu wewe ni kimsingi kwenda kushughulika na picha mbili bitmap.

432
00:36:21,410 --> 00:36:23,410
Wewe unataka kuhakikisha kwamba unatumia moja ya haki.

433
00:36:23,410 --> 00:36:26,820
Wakati wewe ni kuhesabu padding kwa outfile, unataka kutumia upana wa outfile

434
00:36:26,820 --> 00:36:29,860
na si upana wa moja uliopita.

435
00:36:29,860 --> 00:36:37,240
>> Mkuu. Kwamba aina ya huduma inachukua kukaza nzima bitmap image usawa.

436
00:36:37,240 --> 00:36:41,290
Lakini nini tunataka kufanya ni kweli kunyoosha kwa wima pia.

437
00:36:41,290 --> 00:36:48,760
Hii ni kwenda kuwa kidogo trickier sababu wakati tumekuwa kumaliza kuiga mstari

438
00:36:48,760 --> 00:36:51,580
na kuandika kuwa mstari, mshale yetu ni kwenda kuwa mwishoni.

439
00:36:51,580 --> 00:36:56,210
Hivyo kama sisi kusoma tena, basi tu kwenda kusoma katika mstari wa pili.

440
00:36:56,210 --> 00:37:03,660
Basi nini tunataka kufanya ni aina ya kupata baadhi ya njia ya kuiga safu wale tena

441
00:37:03,660 --> 00:37:12,500
au aina tu ya kuchukua kwamba mstari na kisha kuandika tena.

442
00:37:14,380 --> 00:37:17,940
Kama mimi aina ya alluded, kuna tofauti ya njia ya kufanya hii.

443
00:37:17,940 --> 00:37:23,040
Nini unaweza kufanya ni kama utaenda kupitia na kusoma kupitia scanline fulani

444
00:37:23,040 --> 00:37:28,560
na kubadilisha kama ni lazima, basi aina ya kuhifadhi yote ya saizi ya wale katika safu.

445
00:37:28,560 --> 00:37:36,350
Kisha baadaye juu ya wewe kujua kuwa wewe utakuwa haja ya magazeti ya nje kwamba safu tena,

446
00:37:36,350 --> 00:37:39,830
na hivyo unaweza kutumia tu kwamba safu ya kufanya hivyo.

447
00:37:39,830 --> 00:37:44,500
Njia nyingine ya kufanya hivyo ni wewe wanaweza kunakili chini moja mstari,

448
00:37:44,500 --> 00:37:47,950
kuelewa kwamba unahitaji nakala kwamba tena, hivyo kwa kweli hoja cursor yako,

449
00:37:47,950 --> 00:37:50,950
na kwamba itakuwa ni ya kutumia fseek mbinu.

450
00:37:50,950 --> 00:37:56,410
Unaweza hoja cursor yako njia yote nyuma na kisha kurudia utaratibu nakala tena.

451
00:37:56,410 --> 00:38:03,960
>> Hivyo kama kuongeza idadi yetu ni n, basi ni mara ngapi itakuwa tuna kwenda nyuma

452
00:38:03,960 --> 00:38:10,500
na rewrite mstari? >> [Mwanafunzi] n - 1. >> Yeah, kamilifu. n - 1.

453
00:38:10,500 --> 00:38:14,390
Tumefanya hivyo mara moja tayari, hivyo basi tutaweza wanataka kurudia kurejea mchakato

454
00:38:14,390 --> 00:38:17,460
n - 1 kiasi cha mara.

455
00:38:22,730 --> 00:38:25,860
Sawa. Hivyo kuna una resize yako kazi.

456
00:38:25,860 --> 00:38:34,360
>> Sasa tunaweza kupata sehemu kweli fun, pset favorite, ambayo ni Kuokoa.

457
00:38:34,360 --> 00:38:39,580
Badala ya bitmaps, wakati huu sisi ni kushughulika na JPEGs.

458
00:38:39,580 --> 00:38:43,370
Sisi ni kweli si kupewa faili tu ya JPEGs,

459
00:38:43,370 --> 00:38:46,600
sisi ni kupewa kimsingi ghafi kumbukumbu kadi format.

460
00:38:46,600 --> 00:38:51,790
Na hivyo hii ina kidogo ya maadili info na takataka katika mwanzo,

461
00:38:51,790 --> 00:38:57,240
na kisha ni kuanza na ina rundo la files JPEG.

462
00:38:57,240 --> 00:39:03,430
Hata hivyo, sisi ni kukabidhiwa kadi ambapo tumekuwa ilifutwa photos;

463
00:39:03,430 --> 00:39:08,300
kimsingi, tumesahau ambapo picha ziko ndani ya kadi.

464
00:39:08,300 --> 00:39:12,770
Hivyo basi kazi yetu katika Kuokoa ni kwenda kupitia muundo huu kadi

465
00:39:12,770 --> 00:39:16,500
na kupata picha hizo tena.

466
00:39:16,500 --> 00:39:23,990
>> Kwa bahati, muundo wa files JPEG na faili kadi ni kidogo kusaidia.

467
00:39:23,990 --> 00:39:28,850
Ni dhahiri wangeweza kidogo trickier kama si katika format fulani.

468
00:39:28,850 --> 00:39:40,160
Kila faili JPEG kweli kuanza kwa Mwandamano mbili inawezekana, waliotajwa hapo juu.

469
00:39:40,160 --> 00:39:42,970
Kimsingi, wakati wowote una mpya JPEG faili,

470
00:39:42,970 --> 00:39:52,720
inaanza na mlolongo ama ffd8 ffe0 au nyingine moja, ffd8 ffe1.

471
00:39:52,720 --> 00:39:59,530
Jambo jingine kusaidia kujua ni kwamba JPEGs ni kuhifadhiwa contiguously.

472
00:39:59,530 --> 00:40:03,380
Hivyo kila mmoja JPEG faili mwisho, nyingine moja kuanza.

473
00:40:03,380 --> 00:40:07,070
Hivyo hakuna aina yoyote ya katika-kati ya maadili huko.

474
00:40:07,070 --> 00:40:15,510
Mara baada ya kuanza kwa hit JPEG, kama wameweza tayari kusoma JPEG,

475
00:40:15,510 --> 00:40:21,800
unajua kwamba ve hit mwisho wa mmoja uliopita na kuanza moja ijayo.

476
00:40:21,800 --> 00:40:25,890
>> Ili aina ya taswira hii, mimi alifanya schematic.

477
00:40:25,890 --> 00:40:36,910
Jambo jingine kuhusu JPEGs ni kwamba tunaweza kuzisoma katika mifuatano ya ka 512 kwa wakati mmoja,

478
00:40:36,910 --> 00:40:39,380
vile vile na mwanzo wa kadi.

479
00:40:39,380 --> 00:40:43,370
Hatuna haja ya kuwa na kuangalia kila Byte moja kwa sababu kwamba ingekuwa Suck.

480
00:40:43,370 --> 00:40:48,200
Hivyo badala yake, nini tunaweza kufanya ni kweli tu kusoma katika bytes 512 wakati

481
00:40:48,200 --> 00:40:54,700
na kisha, badala ya kuangalia katika kati ya wale katika vipande wale kidogo kidogo,

482
00:40:54,700 --> 00:40:58,640
tunaweza kuangalia tu mwanzo wa ka 512.

483
00:40:58,640 --> 00:41:02,570
Kimsingi, katika picha hii, nini kuona ni mwanzo wa kadi,

484
00:41:02,570 --> 00:41:08,700
una maadili ambayo ni kweli si muhimu kwa JPEGs halisi wenyewe.

485
00:41:08,700 --> 00:41:15,830
Lakini basi nini mimi ni nyota zinaonyesha moja ya Mwandamano mbili kuanzia kwa JPEG.

486
00:41:15,830 --> 00:41:19,910
Hiyo wakati wowote, unaweza kuona nyota, unajua kwamba una faili JPEG.

487
00:41:19,910 --> 00:41:25,030
Na kisha kila faili JPEG ni kwenda kuwa baadhi ya ka nyingi 512

488
00:41:25,030 --> 00:41:27,880
lakini si lazima nyingi sawa.

489
00:41:27,880 --> 00:41:32,050
njia ambayo unajua kwamba ve hit nyingine JPEG ni kama hit mwingine nyota,

490
00:41:32,050 --> 00:41:39,090
mwingine mlolongo kuanzia ya ka.

491
00:41:39,090 --> 00:41:43,330
Kisha nini una hapa ni wewe kuwa nyekundu JPEG faili kuendelea mpaka hit nyota,

492
00:41:43,330 --> 00:41:45,150
ambayo ni unahitajika kwa rangi mpya.

493
00:41:45,150 --> 00:41:48,510
Wewe kuendelea na kisha hit mwingine nyota, wewe hit nyingine JPEG,

494
00:41:48,510 --> 00:41:50,590
wewe kuendelea njia yote hadi mwisho.

495
00:41:50,590 --> 00:41:53,180
Uko katika picha ya mwisho hapa, moja pink.

496
00:41:53,180 --> 00:41:58,220
Unaweza kwenda mpaka mwisho hit mwisho wa tabia ya faili.

497
00:41:58,220 --> 00:42:00,820
Hii ni kwenda kuwa muhimu kweli kweli.

498
00:42:00,820 --> 00:42:03,170
>> chache kuu takeaways hapa:

499
00:42:03,170 --> 00:42:06,670
faili kadi haina kuanza na JPEG,

500
00:42:06,670 --> 00:42:13,350
lakini mara moja JPEG kuanza, wote wa JPEGs ni kuhifadhiwa upande kwa upande mmoja na mwingine.

501
00:42:17,520 --> 00:42:20,420
>> Baadhi pseudocode kwa Kuokoa.

502
00:42:20,420 --> 00:42:22,570
Kwanza, sisi ni kwenda kufungua kadi yetu ya SVG,

503
00:42:22,570 --> 00:42:27,500
na kwamba itakuwa ni ya kutumia faili yetu I / O kazi.

504
00:42:27,500 --> 00:42:32,430
Sisi ni kwenda kurudia utaratibu zifuatazo mpaka tumekuwa kufikiwa mwisho wa faili.

505
00:42:32,430 --> 00:42:36,450
Sisi ni kwenda kusoma ka 512 wakati huo.

506
00:42:36,450 --> 00:42:39,180
Na kile Mimi alisema hapa ni tunakwenda kuhifadhi katika buffer,

507
00:42:39,180 --> 00:42:46,230
hivyo kimsingi kushikilia wale ka 512 mpaka sisi kujua hasa nini cha kufanya na wao.

508
00:42:46,230 --> 00:42:50,300
Kisha nini tunataka kufanya ni tunataka kuangalia kama tumekuwa hit nyota au la.

509
00:42:50,300 --> 00:42:57,960
Kama tumekuwa hit nyota, kama tumekuwa hit mmoja wa Mwandamano kuanzia,

510
00:42:57,960 --> 00:42:59,980
basi tunajua kwamba tumekuwa hit mpya JPEG faili.

511
00:42:59,980 --> 00:43:08,860
Nini sisi utasikia wanataka kufanya ni tunakwenda wanataka kujenga faili mpya katika directory yetu pset4

512
00:43:08,860 --> 00:43:14,480
kuendelea kufanya kwamba faili.

513
00:43:14,480 --> 00:43:18,220
Lakini pia, kama tumekuwa tayari alifanya JPEG kabla,

514
00:43:18,220 --> 00:43:25,620
kisha tunataka kukomesha kwamba faili na kuiondoa kwa folder pset4,

515
00:43:25,620 --> 00:43:29,780
ambapo tutaweza kuwa na faili kwamba kuhifadhiwa kwa sababu kama hatuwezi bayana kwamba tumekuwa kumalizika kwamba JPEG faili,

516
00:43:29,780 --> 00:43:37,290
kisha tutaweza kimsingi kuwa kiasi indeterminate. JPEGs hautakuwa na mwisho.

517
00:43:37,290 --> 00:43:40,840
Hivyo tunataka kuhakikisha kwamba wakati sisi ni kusoma katika faili la JPEG na kuandika kwamba,

518
00:43:40,840 --> 00:43:46,590
tunataka hasa karibu kwamba ili kufungua moja ijayo.

519
00:43:46,590 --> 00:43:48,430
Tutaweza wanataka kuangalia mambo kadhaa.

520
00:43:48,430 --> 00:43:52,880
Tunataka kuangalia kama sisi ni wakati wa kuanza JPEG mpya na buffer wetu

521
00:43:52,880 --> 00:43:56,780
na pia kama sisi tayari wamegundua JPEG kabla

522
00:43:56,780 --> 00:44:03,930
kwa sababu hiyo itabadilisha mchakato wako kidogo.

523
00:44:03,930 --> 00:44:07,880
Hivyo basi baada ya wewe kwenda kupitia njia yote na wewe hit mwisho wa faili,

524
00:44:07,880 --> 00:44:11,570
basi kile utasikia wanataka kufanya ni wewe utakuwa unataka kufunga files wote kwamba sasa kufungua.

525
00:44:11,570 --> 00:44:14,100
Hiyo pengine kuwa mwisho JPEG faili kwamba una,

526
00:44:14,100 --> 00:44:18,930
kama vile faili kadi kwamba tumekuwa kushughulika na.

527
00:44:21,940 --> 00:44:28,670
>> kikwazo cha mwisho tunahitaji kukabiliana na ni jinsi gani ya kweli kufanya faili JPEG

528
00:44:28,670 --> 00:44:31,950
na jinsi ya kweli kuiondoa kwa folder.

529
00:44:33,650 --> 00:44:39,850
pset inahitaji kwamba kila JPEG kwamba kupata kuwa katika muundo ufuatao,

530
00:44:39,850 --> 00:44:43,990
ambapo una idadi jpg..

531
00:44:43,990 --> 00:44:50,750
idadi, hata kama ni 0, sisi kuiita 000.jpg.

532
00:44:50,750 --> 00:44:55,730
Kila wewe kupata JPEG katika mpango wako,

533
00:44:55,730 --> 00:44:58,040
wewe ni kwenda kutaka jina hilo ili ni kupatikana.

534
00:44:58,040 --> 00:44:59,700
Hii ina maana gani?

535
00:44:59,700 --> 00:45:03,530
Tunahitaji aina ya kuweka wimbo wa jinsi wengi tumekuwa kupatikana

536
00:45:03,530 --> 00:45:08,680
na nini idadi ya kila JPEG lazima.

537
00:45:08,680 --> 00:45:13,800
Hapa sisi ni kwenda kuchukua faida ya kazi sprintf.

538
00:45:13,800 --> 00:45:17,480
Sawa na printf, ambayo tu aina ya prints thamani nje ndani ya terminal,

539
00:45:17,480 --> 00:45:23,910
sprintf Prints faili nje katika folder.

540
00:45:23,910 --> 00:45:30,870
Na hivyo kufanya nini hii ingekuwa kama alikuwa sprintf, cheo, na kisha kamba huko,

541
00:45:30,870 --> 00:45:36,660
ingekuwa magazeti nje 2.jpg.

542
00:45:36,660 --> 00:45:41,020
Kutokana kwamba nimepata imefungwa files yangu kwa usahihi,

543
00:45:41,020 --> 00:45:47,210
ambayo yana faili kwamba mimi alikuwa kuandika nje.

544
00:45:47,210 --> 00:45:50,320
Lakini jambo moja ni kwamba kificho kwamba mimi hapa

545
00:45:50,320 --> 00:45:53,360
haina kabisa kukidhi kile pset inahitaji.

546
00:45:53,360 --> 00:46:02,410
pset inahitaji pili faili JPEG lazima aitwaye 002 badala ya 2 tu.

547
00:46:02,410 --> 00:46:09,160
Hivyo wakati wewe magazeti nje jina, basi labda unaweza kutaka kubadilisha placeholder kidogo.

548
00:46:09,160 --> 00:46:18,140
>> Je, mtu yeyote kumbuka jinsi sisi kuruhusu kwa ajili ya maeneo ya ziada wakati sisi magazeti kitu?

549
00:46:18,140 --> 00:46:22,530
Yeah. >> [Mwanafunzi] Wewe kuweka 3 kati ya ishara na asilimia 2. >> Yeah, kamilifu.

550
00:46:22,530 --> 00:46:25,610
Wewe itabidi kuweka 3 katika kesi hii kwa sababu tunataka nafasi kwa 3.

551
00:46:25,610 --> 00:46:32,590
% 3d pengine kukupa 002.jpg badala ya 2.

552
00:46:32,590 --> 00:46:40,120
Hoja ya kwanza katika kazi sprintf ni kweli safu Char,

553
00:46:40,120 --> 00:46:42,520
ambayo sisi awali alijua kama masharti.

554
00:46:42,520 --> 00:46:50,700
Wale mapenzi, aina ya zaidi kama kuhifadhi muda, tu kuhifadhi string matokeo.

555
00:46:50,700 --> 00:46:54,950
Wewe si kweli kuwa kushughulika na hii, lakini unahitaji kwa pamoja.

556
00:46:54,950 --> 00:47:00,710
>> Kujua kwamba kila jina faili ina idadi, ambayo inachukua hadi herufi tatu,

557
00:47:00,710 --> 00:47:06,770
na kisha jpg., kwa muda gani lazima safu hii?

558
00:47:09,070 --> 00:47:14,310
Mfukuze idadi. Ngapi wahusika katika cheo, katika jina?

559
00:47:18,090 --> 00:47:26,320
Hivyo kuna 3 hashtags, kipindi, jpg. >> [Mwanafunzi] 7. >> 7. Si kabisa.

560
00:47:26,320 --> 00:47:32,000
Sisi ni kwenda wanataka 8 kwa sababu tunataka kwa ajili ya kuruhusu Terminator null pia.

561
00:47:45,340 --> 00:47:49,730
>> Hatimaye, ili tu kuteka mchakato kuwa wewe utakuwa kufanya kwa ajili ya Kuokoa,

562
00:47:49,730 --> 00:47:55,420
wewe na baadhi ya taarifa mwanzo.

563
00:47:55,420 --> 00:48:02,460
Wewe kuendelea mpaka kupata mwanzo wa faili JPEG,

564
00:48:02,460 --> 00:48:07,900
na kwamba inaweza kuwa ama moja ya Mwandamano mbili kuanzia.

565
00:48:07,900 --> 00:48:12,510
Wewe kuendelea kusoma. Kila slash hapa inawakilisha ka 512.

566
00:48:12,510 --> 00:48:22,630
Wewe kuendelea kusoma, kuendelea kusoma mpaka wakutane mwingine mlolongo kuanzia.

567
00:48:22,630 --> 00:48:29,790
Mara tu na kwamba, wewe mwisho JPEG sasa - katika kesi hii, ni moja nyekundu,

568
00:48:29,790 --> 00:48:31,030
hivyo unataka kukomesha hiyo.

569
00:48:31,030 --> 00:48:35,540
Unataka jina sprintf ya kwamba ndani ya folda yako pset4,

570
00:48:35,540 --> 00:48:41,580
kisha unataka kufungua JPEG mpya na kisha kuendelea kusoma

571
00:48:41,580 --> 00:48:46,370
mpaka wakutane ijayo.

572
00:48:46,370 --> 00:48:49,040
Endelea kusoma, kuendelea kusoma,

573
00:48:49,040 --> 00:48:56,290
na kisha hatimaye, hatimaye, utaenda kufikia mwisho wa faili,

574
00:48:56,290 --> 00:49:00,360
na hivyo utasikia wanataka kuifunga JPEG mwisho kwamba wewe walikuwa wakifanya kazi pamoja,

575
00:49:00,360 --> 00:49:08,380
sprintf kwamba ndani ya folda yako pset4, na kisha kuangalia aina ya picha kwamba ve Gotten.

576
00:49:08,380 --> 00:49:12,050
Wale picha ni kweli picha ya wafanyakazi CS50,

577
00:49:12,050 --> 00:49:16,430
na hivyo hii ni sehemu ambapo fun ziada ya pset inakuja katika

578
00:49:16,430 --> 00:49:26,310
ni kwamba wewe ni kushindana katika sehemu yako ya kupata TFS katika picha

579
00:49:26,310 --> 00:49:34,610
na kuchukua picha pamoja nao ili kuthibitisha kuwa umefanya kosa pset

580
00:49:34,610 --> 00:49:37,030
na hivyo unaweza kuona ambayo wafanyakazi wanachama ni katika picha.

581
00:49:37,030 --> 00:49:41,510
Hivyo basi wewe kuchukua picha na wafanyakazi. Wakati mwingine itabidi baada yao chini.

582
00:49:41,510 --> 00:49:44,680
Pengine baadhi yao kujaribu kukimbia mbali na wewe.

583
00:49:44,680 --> 00:49:47,320
Unaweza kuchukua picha na yao.

584
00:49:47,320 --> 00:49:51,190
Hii ni unaoendelea. Ni wakati si kutokana pset ni kutokana.

585
00:49:51,190 --> 00:49:53,340
tarehe ya mwisho yatatangazwa katika spec.

586
00:49:53,340 --> 00:49:58,060
Kisha pamoja na sehemu yako, kwa namna yoyote sehemu inachukua picha zaidi

587
00:49:58,060 --> 00:50:04,430
na wanachama wengi wafanyakazi kushinda tuzo pretty kutisha.

588
00:50:04,430 --> 00:50:08,890
Hiyo ni aina ya motisha ya kupata pset4 yako kumaliza kwa haraka iwezekanavyo

589
00:50:08,890 --> 00:50:10,820
kwa sababu basi unaweza kupata chini ya biashara

590
00:50:10,820 --> 00:50:14,570
wanawinda mbalimbali wanachama wote wafanyakazi CS50.

591
00:50:14,570 --> 00:50:17,500
Hiyo si lazima, ingawa, hivyo mara moja kupata picha,

592
00:50:17,500 --> 00:50:20,310
basi wewe ni kumaliza na pset4.

593
00:50:20,310 --> 00:50:23,970
>> Na mimi nina kumaliza na walkthrough 4, hivyo kuwashukuru wote kwa kuja.

594
00:50:23,970 --> 00:50:29,330
Bahati nzuri na Forensics. [Applause]

595
00:50:29,330 --> 00:50:31,000
[CS50.TV]