strcspn

(PHP 4, PHP 5)

strcspn — Връща дължината на сегмент в началото на низ, не съответстващ на дадена маска

Описание

int strcspn ( string $str1 , string $str2 [, int $start [, int $length ]] )

Връща дължината на сегмент в началото на низа str1 , която не съдържа никой от указаните в str2 знаци.

Параметри

str1: Първият низ.
str2: Вторият низ.
start: Началната позиция на изследвания низ.
length: Дължината на изследвания низ.

Връщани стойности

Връща дължината на сегмента в целочислен вид.

Дневник на промените

Версия	Описание
4.3.0	Добавени бяха параметрите `start` и `length`

Бележки

Забележка: Тази функция е двоично сигурна (binary-safe).

Вж. също

strspn() - Връща дължината на сегмент в началото на низ, съответстващ на дадена маска

strip_tags

strcoll

[edit] Last updated: Fri, 18 Sep 2009

add a note User Contributed Notes strcspn

legacyprog at routinz dot net 09-Dec-2010 12:20


When you use the third parameter remember that the function will return the number of characters it bypassed, which will *not* be the position in your source string.  It's a simple fix to just add your third parameter value to the function result to get the position in the first string where the scan stopped, but I didn't think of it at first.

Anonymous 16-Oct-2009 04:55


strcspn() can also be thought of as analogous to the following regular expression:

<?php

// where ... represents the mask of characters

preg_match('/[^ ...]/', substr($subject, $start, $length) );

?>

By this analogy, strcspn() can be used in place of some regular expressions to match a pattern without the overhead of a regex engine -- for example, ways to verify if an input string represents a binary value:

<?php

preg_match('/^[01]+$/i', $subject);

// or...

!preg_match('/[^01]/i', $subject);



// ...or using strcspn()

!strcspn($subject, '01');

?>

Dmitry Mazur 04-Mar-2009 03:17


The second parameter simply is the set of the "stop"-characters.

In other words, this function will return the index (starting from 0) of a first occurence of the stop-character.

PHP at NospamImmortalSoFar dot com 07-Oct-2006 12:31


Also useful for breaking down expressions - for example parsing SQL: values ('this', fn("that,)()", 4))



$sep = strcspn ($list, "'\"`");     //    Start of quoted string

$list = substr ($list, $sep);

$find = substr ($list, 0, 1);

while (($sep = strpos ($list, $find, $sep+1)) > 0 && substr ($list, $sep-1, 1) == '\\')

    {}

//  $sep now spans the entire string, regardless of embedded quotes



Once the strings have been removed, an expression can then be parsed for commas and brackets without worrying about them:



while ($out != '')

{

    $sep = strcspn ($list, "(),");      //  Next seperator

...

}

AT-HE (at_he AT hotmai1 DOT com) 26-Dec-2005 07:07


this function can be used like strspn(), except while that can be used to compare a string with an allowed pattern, this one can be use to compare a string with a FORBIDDEN pattern



so, to know if any forbidden character has a position inside our string, we can use (not tested with backslashes)...



<?php

// LARGE VERSION

$forbidden="\"\\?*:/@|<>";

if (strlen($filename) != strcspn($filename,$forbidden)) {

    echo "you cant create a file with that name!";

}



// SHORT VERSION

if (strlen($filename) - strcspn($filename,"\"\\?*:/@|<>")) {

    echo "i told you, you cant create that file";

}

?>

maskedcoder at hotmail dot com 10-Oct-2005 10:13


useful for finding beginning of quotes and/or tags in a variable containing html.  

    $pos = strcspn($data, '<"\''); 

will find the first occurance of either the beginning of a tag, or a double- or single-quoted string.

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