PHP Australia Conference 2015

strcspn

(PHP 4, PHP 5)

strcspnEncuentra la longitud del segmento inicial que no coincida con la máscara

Descripción

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

Devuelve la longitud del segmento inicial de str1 el cual no contiene ningún caracter de str2.

Parámetros

str1

El primer string.

str2

El segundo string.

start

La posición inicial en el string a examinar.

length

La longitud del string a examinar.

Valores devueltos

Devuelve la longitud del segmento como un integer.

Ejemplos

Ejemplo #1 strcspn() example

<?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);
?>

El resultado del ejemplo sería:

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

Notas

Nota: Esta función es segura binariamente.

Ver también

  • strspn() - Encuentra la longitud del segmento inicial de un string que consista únicamente en caracteres contenidos dentro de una máscara dada.

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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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