php man page for strspn

STRSPN(3)								 1								 STRSPN(3)

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

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

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

	If  $start and $length are omitted, then all of $subject will be examined. If they are included, then the effect will be the same as call-
       ing strspn(substr($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");
       ?>
       2 to $var, because the string "42" is the initial segment of $subject that consists only of characters contained within "1234567890".

PARAMETERS
	      o $subject
		- The string to examine.

	      o $mask
		- The list of allowable characters.

	      o $start
		- The position in $subject to start searching.	If $start is given and is non-negative, then strspn(3) will begin examining  $sub-
		ject at the $start'th position. For instance, in the string ' abcdef', the character at position 0 is ' a', the character at posi-
		tion 2 is ' c', and so forth.  If $start is given and is negative, then strspn(3) will begin examining $subject at  the  $start'th
		position from the end of $subject.

	      o $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 $length is 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.

EXAMPLES
       Example #1

	      strspn(3) 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.

SEE ALSO
       strcspn(3).

PHP Documentation Group 														 STRSPN(3)