PHP Xyaum: txoj hlua sib piv

PHP yog teem rau zoo ntaub ntawv tuav. Cov syntax ntawm cov lus yog sawv cev tag nrho tej qhov txheej ntawm kev sib piv zog, txoj hlua ua, kev sib piv tswv.

Tej algorithm - ib theem ntawm cov kev xaiv thiab kev ua. Tab sis ua ntej koj ua ib qho kev xaiv, koj yuav tsum ib yam dab tsi los sib piv nws nrog ib yam dab tsi. Kab - lub feem ntau capacious, npaum thiab cov tswv yim algorithm tswj mechanism. Kab - ib tug variant ntawm cov ntaub ntawv nthuav qhia. Ib tug cov ntaub ntawv - qhov no yog qhov tseem ceeb kev kawm ntawm "pab" ntawm tej algorithm.

Ordinary logic "kev sib piv-kev txiav txim"

Nyob rau hauv kev, dynamic typing tus nplaig puas tsis muaj sib txawv nyob rau hauv cov ntaub ntawv, xws li PHP sib piv kab thiab tus naj npawb yog tsis ntau sib txawv. Tooj - nws tseem yog ib txoj hlua, thaum nws muaj xwb tus xov tooj, taw tes thiab tsis muaj ib tug tib cim uas tsis yog siv los mus sawv cev rau tus xov tooj nyob rau hauv tej daim ntawv (mathematical cim).

Yog hais tias kontenkatsii tooj txiav merges nrog rau cov kab, tsis muaj cov lus nug thiab tsis muaj thaum uas tsis, txawm hais tias gettype () muaj nuj nqi muab lub 'integer' los yog 'ob'.

Txawm li cas los, muaj dab tsi sib txawv ntawm kev siv is_int () thiab is_numeric (). Tus thawj muab qhov tseeb, tsuas yog thaum lub parameter yog ib qho integer, thib ob, thaum muaj xov tooj los yog numeric txoj hlua (nce mus nce los hom yog 'txoj hlua, tab sis muaj tag nrho cov muab xaam cim).

Qhov no yog ib tug piv txwv yooj yim - ib tug zoo piv txwv ntawm yuav ua li cas ib tug PHP txoj hlua sib piv tswv ( '==' '===' ...! = ') Yuav muaj ntau surprises. Cov tsiaj ntawv muaj peev xwm hloov lawv hom, lawv tsis yog ib txwm tus xov tooj, tab sis yuav luag ib txwm lawv yuav ua tau kom txoj kab. Nyob rau hauv ib tug huab rooj plaub - nws yuav tsum tau ib qho kev npliag hlua.

Raws li cov saum toj no, ib tug PHP txoj hlua sib piv muaj nuj nqi yog feem ntau nrov. Yuav ua li cas raws nraim xaiv, los txiav txim tus tsim tawm. Ntau cov kev xaiv muaj li rau kev kab zauv.

Ib thaj tsam ntawm cov muaj kev haumxeeb

PHP-sib piv ntawm ob kab yog zoo "ua" muaj nuj nqi strpos () - pheej yig tshaj, tus ncaj ncees thiab cov tswv yim kev xaiv. Yog hais tias qhov tshwm sim ntawm cov nuj nqi xov tooj, ces kom meej meej ib txoj hlua yog sib npaug zos mus rau lwm lub los yog ib feem mus rau lwm lub.

Radically opposite, tab sis kuj kiag li txoj cai mus kom ze - qhov siv ntawm kev kab zauv.

Yog hais tias cov nuj nqi $ cResult = scCheckFileName ($ cStr) muab 'tseeb', ces cov kab yog ib lub npe ntawm cov ntaub ntawv vordovsky. Nws yuav muaj tsuas yog ib txoj kev xaiv ntawm expansion '.docx' thiab tsis muaj cov cim nyob rau hauv lub npe: tsuas tsiaj ntawv, lej tom qab thiab lub cim '_', '-'.

Cov nuj nqi yuav muab tau yooj yim hloov dua siab tshiab rau lwm yam ntawm cov ntaub ntawv: $ cPtr = '/^([a-zA-Z...0-9\-\_]{4,239})\.(html|js|css|png|jpg | docx | txt) {1} $ / u '. Qhov no variant ncua lub ntau yam scan kab downloadable (e.g., PHP txoj hlua sib piv yog thov "upload ntaub ntawv mus rau ib tug neeg rau zaub mov, uas tsis muaj lub caij nyoog ntawm cov tswv yim kev ua yuam kev") rau html, js, css, ...

Siv cov strpos () thiab preg_match () - extremes. Lawv tsis yog cov muaj feem xyuam rau qhov teeb meem ntawm cov kev sib piv lub sij hawm. Tab sis cov nqe lus nug ntawm lub algorithm - yog ib tug teeb meem ntawm kev siv ib tug ua ke ntawm style, siv tag nrho lub sij hawm mus cuag ib tug txhim khu kev qha thiab yog tshwm sim.

Kev PHP: txoj hlua sib piv

Arsenal lus piv cov hlua - ib tug dawb huv, tsis tsuas cov kev sib piv muaj nuj nqi, tab sis kuj yog ib tug ua ke ntawm ib tug kev tshawb fawb los yog kev hloov ncaj qha. Tsis yeej ib txwm ua yuav tsum coincide nrog cov kev sib piv, txij thaum lub caij nyoog kawg no tsis tau ua rau ib tug kev hloov nyob rau hauv tej kab. Feem ntau koj yuav tsum xaiv ib tug los yog lwm yam ceg ntawm lub algorithm.

Tej variant PHP: ua txoj hlua sib piv muaj nuj nqi rau cov menyuam strcmp (s1, s2).

Cov tshwm sim ntawm cov kev ua:

• 0 - kab yog muaj sib npaug;
• -1 - tus thawj txoj hlua yog tsawg tshaj li qhov thib ob;
• 1 - tus thawj ntau tshaj lub thib ob kab.

Nyob rau hauv kev xyaum, qhov no txhais tau tias yog ib feem ntawm cov thawj kab mus rau lub thib ob, los ntawm uas PHP muaj nuj nqi (kev sib piv kab) txiav txim siab. Ib tug ntau tsawg version ntawm strpos (), vim hais tias nyob rau hauv lub caij nyoog kawg no rooj plaub no nws yog tau paub txoj hauj lwm ntawm lub qhov rooj.

strcmp () muaj nuj nqi - sensitive. Yog hais tias koj xav tau los sib piv cov hlua-insensitive, PHP muaj nws strcasecmp (). Cov syntax yog zoo sib xws.

Nyob rau hauv kev xyaum feem ntau yuav tsum tau mus ua hauj lwm tsis nrog rau tag nrho cov kab, tab sis tsuas yog ib feem ntawm nws. Rau no set ntawm kev khiav dej num PHP (txoj hlua sib piv) muaj strncmp (s1, s2, N). Qhov thib peb parameter qhia ua cov kev sib piv xwb N-bytes. Cov no zoo xws li cov strcmp ().

Arrays, cov hlua thiab muab piv

Cov no yog yuav luag ib txwm sawv cev los ntawm cov hlua. Yog hais tias peb xav txog cov arrays, tej khoom, los yog cov ntaub ntawv lug, nws cia li sib txawv variants ntawm ob peb ua ke ntawm ib tug yooj yim txoj hlua lug.

Hlua arrays thiab kab yuav muab nyob rau hauv ib tug complementary yam. Transformation ntawm lub array rau hauv ib txoj hlua muaj nuj nqi implode (array, cim), piv txwv li: $ margins1 = implode ( ',', $ style-> getInnerMargin ()); ... lub algorithm / neeg ...; $ Margins2 = implode ( ',', $ style-> getInnerMargin ()) tso cai rau koj mus hauj lwm ua ke tag nrho cov khoom nyob rau hauv txoj hauj lwm txoj hlua txoj hauj lwm.

Koj muaj peev xwm ces ua lub PHP txoj hlua sib piv, thiab nyob ib lub sij hawm: $ check = strcmp ($ margins1, $ margins2) thiab kom paub tseeb tias cov algorithm los yog tus neeg siv uas ib yam dab tsi tau hloov (los yog tsis). Yog hais tias koj ua tau ib tug kev sib piv nyob rau hauv lub niaj zaus txoj kev, koj yuav tau xaiv cov array ntsiab. Nws yuav siv sij hawm ntev thiab yog nyuab dua.

Khoom thiab kab

Txawm ntau spectacular siv PHP (txoj hlua sib piv) tau muab los siv ntawm yam khoom-taw qhia kom paub cov tswv yim.

Cov niaj hnub lub tswv yim ntawm cov chaw qhia hais tias lawv muaj zog thiab cov hau kev. Cov yav tas los no feem ntau yog sawv cev los ntawm tus xov tooj, cov hlua, arrays, thiab lwm yam khoom. Cov yav tas feem ntau muaj xws li cov ntaubntawv povthawj siv hom kev kawm (muab) nyob rau hauv lub rov qab kab thiab los ntawm kab (tau).

Tsis zoo li arrays, tus kwv tsis ua hauj lwm rau lawv tus kheej lub zog thiab ua num ua ke nrog rau lwm cov khoom. Nruas "competent" nyob rau hauv uas nws cov khoom yog tiag tiag tus nqi rau cov algorithm ntawm qhov kev pab cuam raws li ib tug tag nrho.

Qhov no lub sij hawm ntawd muaj ib tug hauv paus thiab lub sij hawm los sau thaum teev ib txoj hlua tsuas yog tus ntaub ntawv tsim nyog, thiab nyob rau hauv lub rov qab los ntawm cov kab los tag nrho cov ua hauj lwm cov khoom nyob rau hauv cov yam lub xeev. Feem ntau, nyob rau hauv ib yam khoom muaj ntau yam pauv loj cov ntaub ntawv thiab ua hauj lwm (lub sij hawm). Cov kev siv ntawm lub tswv yim no tso cai rau koj mus cawm tsis tau tsuas yog nco, disk qhov chaw, lub database ntaub ntawv, tab sis kuj ua rau nws tau los sib piv cov kab zauv thiab ntau yog txhais tau tias.

Syntax thiab semantics

PHP yog tsim dynamically, thiab nws cov functionality ob leeg nyob rau cov nqe lus piv cov hlua thiab lossi zoo nyob rau hauv cov nqe lus ntawm lawv cov kev kho mob. Txawm li cas los, tsis muaj dab tsi tiv thaiv tus tsim tawm yuav tawm mus qhov chaw ntawm lub ntiajteb txawj nqus nyob rau hauv lub cheeb tsam ntawm semantics.

Undoubtedly, cov functionality yog zoo, tab sis nws siv tau tau kis nyob rau hauv lub ntsiab lus ntawm cov cai nyob rau hauv tej khoom. Thaum lub algorithm yog hais raws li ib tug system ntawm kev sis raug zoo ntawm cov khoom, nws zoo npaum li cas zoo dua ib theem zuj zus los sib piv thiab kev nqis tes ua nyob rau hauv ncaj qha ib theem zuj zus, ib tug classical style.