function strspn - Finds the length of the initial segment of a string consisting entirely of characters contained within a given mask.

Description

int strspn ( string $subject , string $mask [, int $start [, int $length ]] )

Finds the length of the initial segment of subject that contains only characters from mask.

If start and length are omitted, then all of subject will be examined. If they are included, then the effect will be the same as calling strspn(substr($subject, $start, $length), $mask) (see substr for more information).

The line of code:

 <?php
$var = strspn("42 is the answer to the 128th question.", "1234567890");
?>

will assign 2 to $var, because the string "42" is the initial segment of subject that consists only of characters contained within "1234567890".

Parameters

subject

The string to examine.

mask

The list of allowable characters.

start

The position in subject to start searching.

If start is given and is non-negative, then strspn() will begin examining subject at the start'th position. For instance, in the string 'abcdef', the character at position 0 is 'a', the character at position 2 is 'c', and so forth.

If start is given and is negative, then strspn() will begin examining subject at the start'th position from the end of subject.

length

The length of the segment from subject to examine.

If length is given and is non-negative, then subject will be examined for length characters after the starting position.

If lengthis given and is negative, then subject will be examined from the starting position up to length characters from the end of subject.

Return Values

Returns the length of the initial segment of subject which consists entirely of characters in mask.

Changelog

Version	Description
4.3.0	The `start` and `length` parameters were added

Examples

Example #1 strspn() example

 <?php
// subject does not start with any characters from mask
var_dump(strspn("foo", "o"));

// examine two characters from subject starting at offset 1
var_dump(strspn("foo", "o", 1, 2));

// examine one character from subject starting at offset 1
var_dump(strspn("foo", "o", 1, 1));
?>

The above example will output:

 int(0) int(2) int(1)

Notes

Note: This function is binary-safe.