PHP Australia Conference 2015

strcspn

(PHP 4, PHP 5)

strcspnTrouve un segment de chaîne ne contenant pas certains caractères

Description

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

Retourne la taille du premier segment de str1 qui ne contient aucun des caractères de str2.

Liste de paramètres

str1

La première chaîne.

str2

La seconde chaîne.

start

La position sur la chaîne à partir de laquelle on analyse.

length

La taille à examiner de la chaîne.

Valeurs de retour

Retourne la longueur du segment, sous la forme d'un entier.

Exemples

Exemple #1 Exemple avec strcspn()

<?php
$a 
strcspn('abcd',  'apple');
$b strcspn('abcd',  'banana');
$c strcspn('hello''l');
$d strcspn('hello''world');

var_dump($a);
var_dump($b);
var_dump($c);
var_dump($d);
?>

L'exemple ci-dessus va afficher :

int(0)
int(0)
int(2)
int(2)

Notes

Note: Cette fonction gère les chaînes binaires.

Voir aussi

  • strspn() - Trouve la longueur du segment initial d'une chaîne contenant tous les caractères d'un masque donné

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User Contributed Notes 4 notes

up
1
maskedcoder at hotmail dot com
8 years ago
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.
up
1
AT-HE (at_he AT hotmai1 DOT com)
8 years ago
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";
}
?>
up
0
legacyprog at routinz dot net
3 years ago
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.
up
-1
Anonymous
4 years ago
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');
?>
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