"Pascal" - ib hom lus ... "Pascal" rau beginners: hauj lwm

Nyob rau hauv lub vastness ntawm lub ntiaj teb dav Web, koj yuav nrhiav tau ib tug ntau ntawm cov kev pab cuam nyob rau hauv cov lus "Pascal", tab sis ntau npaum li cas yooj yim kom paub tseeb yuav ua li cas lawv ua hauj lwm, thiab cov txheej txheem ntawm nyob rau hauv dab tsi hauv paus. Cia xyuas cov qauv rau kev programming ua ke!

Algorithmic lus: tswv yim

Nyob rau hauv colloquial hais lus peb siv qhov yooj yim units: cov cim, lo lus, nqe lus thiab tag nrho ua ke. Algorithmic lus kuj muaj ib tug uas zoo sib xws qauv, tab sis nws lub Cheebtsam yog hu ua txawv. Peb yuav tau tham txog yooj yim lug, kab zauv thiab cov nqe lus. Tag nrho cov chav nyob tsim ib tug hierarchical qauv, raws li txhua successive caij yog tsim los ntawm cov saum toj no.

Cim algorithmic lus - yog indivisible atoms siv rau kev sau ntawv code.

Basic tsim - yog qhov tsawg kawg nkaus units uas muaj lawv tus kheej lub ntsiab lus.

Classic lus kab zauv yog tsim los ntawm cov saum toj no ob chav nyob thiab qhov chaw kawm cov kev cai rau nrhiav txoj kev xav muaj nuj nqis.

Cov neeg teb xov tooj yog lub luag hauj lwm rau cov hauj lwm ntawm cov kev transformation uas yog tsim nyog rau lawm tua ntawm cov kev pab cuam. Tej zaum yuav muaj ob peb, yog tias tsim nyog - qhov kev pab cuam yuav tsum tau ua ib tug tham lag luam. Nyob rau hauv tej lub sijhawm, lawv nyob ua ke hauv tib lub thaiv los yog compound daim ntawv qhia.

Language "Pascal"

Muaj ib tug loj tus naj npawb ntawm programming lus. "Pascal" (rau beginners muaj ib co kev pab) yog ib tug ntawm lawv. Nws cov niam ntawv yog tsim los ntawm cov xov tooj, cov tsiaj ntawv thiab cim tshwj xeeb. Ntawm no yog ib daim ntawv teev ntawm lawv:

• 26 Latin loj thiab lowercase ntawv ;
• underscore cim;
• kaum tug lej tom qab;
• Limiters;
• lag luam tej yam tshwm sim;
• specifiers;
• reserved los ntawm lub system (pab) ntawm lo lus.

Dhau li ntawm tus saum toj no hais, nws belongs rau ib txheej ntawm yuav tsum muaj "dawb paug" uas yuav siv tsis tau hauv cov qauv thiab cov kev qhia ntawm loo ob cim.

Elementary lus constructs

"Pascal" rau beginners muaj xws li cov hlua, tus xov tooj thiab lub npe.

Cov zauv siv nyob rau hauv lub code nyob rau hauv kev ntsuam xyuas, hom lus programming yog feem ntau sau ib daim ntawv nyob rau hauv tus zauv system. Lawv yuav ua tau ob qho tib si tiag tiag thiab tag nrho, uas tau tsis muaj mention ntawm tus zauv point. Yog hais tias lub xov tooj yog zoo, nws kos npe rau yuav rho.

"Pascal" - yog ib tug algorithmic programming lus nyob rau hauv uas cov hlua yog ib theem ntawm cov cim, kaw nyob rau hauv apostrophes. Yog hais tias koj yuav tau siv ib tug apostrophe nws tus kheej, lub cim yog muaj nqis mentioning ob zaug.

Npe - ib theem uas yuav pib nrog ib tsab ntawv thiab tej zaum yuav muaj nyob rau hauv nws muaj pes tsawg leeg cov nuj nqis. Tawm lawv tus ID yog hu ua cim npe, hom, constants, zog, cov txheej txheem, cov tsiaj, tej khoom, thiab txawm modules. Txoj kev identifiers koj yuav siv lub Underscore cim. Lub npe yuav muaj ib tug ntau ntawm cov ua cim, tab sis lub compiler yuav nyeem tsuas yog thawj 63 cim. "Pascal", muab qhia tawm uas tej zaum yuav zoo li tsis nyuab, tsis yog li ntawd phem heev, yog li tsis txhob Rush mus yuav ntshai thiab kaw lub browser sab!

Raws li cov lus identifiers yog txwv tsis pub siv rau tus txheej txheem npe ntawm constants, cov txheej txheem, hom ntawm cov ntaub ntawv, kev siv, raws li tau zoo raws li system kab zauv.

Txhim kho lub visibility ntawm lub code yuav pab qhov khoob, tab sis nws yog ib nqi nco ntsoov hais tias lawv yuav tsis muab cov npe thiab xov tooj nyob rau hauv nruab nrab.

Syntax algorithmic lus

Txhua kab yuav tsum xaus nrog ib tug semicolon nyob rau hauv qhov kev pab cuam, sau nyob rau hauv cov lus peb xav ( "Pascal"). Informatics qhia cov tub kawm ntawv thiab menyuam kawm ntawv, thiab koj yuav tsum tau to taub cov kev cai rau lawv tus kheej!

Lub semicolon (;) - ib tug prearranged teeb liab, uas qhia txog tus kawg ntawm qhov tam sim no kab thiab yuav tsum tau mus txav mus rau ib tug tshiab. Tab sis tsuas yog rau cov kev pab cuam commands yuav ua tau: const, var, pib thiab lwm tus neeg.

Cov neeg teb xov tooj muab kaw qhov kev pab cuam kawg, li ntawd tom qab nws tas preceded los ntawm ib tug taw tes. Tej zaum code yuav muaj ob peb attachments, ces thaum pib thiab thaum xaus ntawm lub thaiv yuav tau muab cais los ntawm ib tug semicolon.

Yuav kom muab ib lub nqi ntawm cov kuj tsis paub meej ua ntej lub sib npaug kos npe rau yog tsim nyog los muab tso rau ib tug nyuv. Piv txwv li, koj mus rau teem n = 13, thiab cov code yog yuav mus zoo li n: = 13.

Yog hais tias koj kawm cov kev cai, ces koj yuav sai heev kawm sau software code tsis muaj syntax uas tsis.

Classical lus nqe lus "Pascal"

Programmed repetitive neej yav tom ntej daim ntawv thov code thiab siv nws cov kev txiav txim yog tau los ntawm kev txhais tau tias ntawm txoj kev sib txawv. Tab sis cov lus "Pascal" yog siv rau lub hom phiaj no ntau yam tswv. Tag nrho cov ntawm lawv, peb yuav tsis xav txog, yog li ntawd, peb yuav tsum to taub uas muaj ob peb.

Piv txwv li, los ntawm kev xaiv tus neeg muaj peev xwm xaiv ib tug ntawm lwm txoj kev khiav qhov kev pab cuam. Parameter nyob rau hauv cov ntaub ntawv no yog qhov qhia ntawm cov theem zuj zus hom. Tab sis muaj ib tug caveat: no xaiv tseem ceeb yuav tsis muaj ib txoj hlua los yog tiag tiag hom.

Tsis tau muaj hauj lwm cov nqe lus, zwj ceeb, puas thiab npliag, raws li zoo raws li ntau ntau lwm yam tseem ceeb kev nqis peev. Paub txog xwb ib txhia ntawm lawv tso cai rau koj sau cov code uas zoo functionality. Tswv yuav tsum tsis txhob ua phem rau, vim hais tias ntawm lawv cov loj xov tooj ua rau qhov kev pab cuam yooj yim rau debug compiler, ruam tag thiab nyuaj heev rau perceive neeg.

Cov hauj lwm teb xov tooj

Qhov no qhia yog cov nyuv thiab kos npe rau "sib npaug zos". Nws yog siv los muab ib qho kev nce mus nce los ntawm ib tug nqi. Nws yog ib qho tseem ceeb yuav tau nco ntsoov hais tias hom ntawv nce mus nce los kab zauv thiab yuav tsum yog tib nyob rau hauv cov kev tshwm sim hais tias lawv tsis muaj feem xyuam rau tag nrho cov thiab lub sij hom, ntsig txog. Tsuas yog nyob rau hauv xws li ib tug teeb meem no yuav nyiaj tso ncaj hloov dua siab tshiab.

Tiabsis cov nqe lus

"Pascal" - ib tug programming lus uas siv ib tug sib lawv liag ntawm arbitrary kev pab cuam cov nqe lus uas xa tuaj nrog nyob rau hauv tshwj xeeb nkhaus. Nws yog hais txog ib tug puas qauv, lub limited lus pib thiab qhov xaus. Qhov no yog ib qho tseem ceeb lub cuab tam rau cov algorithmic lus uas nws tau sau cov code siv yam ntxwv vib this.

Tswv ntawm cov lus "Pascal", muaj nyob rau hauv rau ib feem ntawm tus qhab qauv tej zaum yuav txawv heev, vim hais tias muaj tsis muaj kev txwv. Zes qhov tob kuj yuav sib txawv.

Conditional neeg teb xov tooj programming lus

Qhov no feem muab lub peev xwm los mus saib nyob rau hauv lub sij hawm qhov kev pab cuam teev mob thiab ua ib tug txiav txim nyob rau cov kev tshwm sim ntawm nws cov zaj. Yog li, lub zwj ceeb kom ua - yog ib tug ntawm cov txhais tau tias ntawm tsim ntawm ceg nyob rau hauv tus txheej txheem ntawm kev ua tau zoo suav.

Structurally, nqe lus yog raws li nram no:

YOG ces Lwm tus .

Nyob rau hauv no qhia lwm tus, ces thiab yog hais tias yog reserved lus, tus mob - ib zajlus kom qhia nrog arbitrary cov ntsiab lus, thiab cov tswv - tej lus txib siv hom lus programming.

Tus qauv ntawm cov kev pab cuam code

Header seem tswv thiab kev qhia txog - cov no yog cov tseem ceeb Cheebtsam ntawm ib daim ntawv thov sau nyob rau hauv ib hom lus xws li "Pascal". Cov ntaub ntawv siv tshuab enables siab tshawb cov ntsiab thiab kawm kom paub siv lawv kom zoo.

Cov header feem ntau muaj ib tug code lub npe. Piv txwv li, Program MyFirst.

Section qhia yuav txhais li cas kev cob cog rua cov tsev qiv ntawv, modules, cov ntawv, constants, hom, ntau yam, tshooj piav qhia ntawm lub zog thiab cov txheej txheem.

Section muaj kev qhia txog ntawm lub modules hauv lub npe ntawm kev cob cog rua cov tsev qiv ntawv thiab pib nrog cov reserved lo lus siv. Nws yuav tsum yog tus thawj ntawm cov tag nrho cov lwm yam kev qhia txog. Module npe yuav tsum yeej ib txwm raug muab cais los ntawm commas.

Tej code neeg teb xov tooj yuav muab tso rau ib daim ntawv lo npe yuav tsum tau hais nyob rau hauv cov nqe lus ntawm qhov kev piav qhia.

Ntxov ntxov hauj lwm tso cai constants nyob rau hauv cov cai hauv qab mus sau npe lawv cov npe es tsis txhob ntawm numeric los yog alphanumeric qhov tseem ceeb.

Nyob rau hauv qhov kev piav qhia ntawm lub zog siv yuav tsum muaj xws li tag nrho cov hom uas yuav siv tau: "var c, ib tug, r: integer; k, l, m: char; H1, h2: boolean;".

Tsis txhob hnov qab hais tias "Pascal" - ib tug programming lus uas yuav tsum tau obligatory yam ua ntej piav qhia ntawm tag nrho cov Cheebtsam muab kev koom tes nyob rau hauv qhov kev pab cuam.

code ntawv nyeem yuav tsum xaus nrog ib teev.

piv txwv ntawm cov kev pab cuam

"Pascal" - qhov no yog ib lub tsev hais lus, thiab koj yuav npaj mus ncaj qha mus rau lub code sau ntawv tom qab kev kawm saum toj no cov lus qhia.

Cia peb xyuas kom meej tias daim ntawv thov tau coj mus rau qhov kev tshuaj ntsuam tus kab lus «Nws yog kuv kev pab thawj zaug!»

Piv txwv ntawm cov kev pab cuam nyob rau hauv "Pascal" yog qho tseem ceeb heev kom to taub, yog li sim ua nws txoj cai tam sim no.

pib
Writeln (Nws yog kuv kev pab thawj zaug '!);
End.

Qhov ntawd yog li ntawd, tej yam yooj yim!

Saib rau ntau code, uas koj yuav nrhiav tau cov keeb kwm ntawm ib tug quadratic equation. Them mloog mus rau cov hauv paus ntsiab lus ntawm tsim ntawm computational kab zauv.

Hopefully, cov piv txwv cov kev pab cuam nyob rau hauv lub "Pascal" yog pab tau rau koj.