(PHP 4, PHP 5)
strcspn — Find length of initial segment not matching mask
$subject
   , string $mask
   [, int $start
   [, int $length
  ]] )
   Returns the length of the initial segment of
   subject which does not
   contain any of the characters in 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 strcspn(substr($subject, $start, $length),
   $mask) (see substr
   for more information).
  
subjectThe string to examine.
maskThe string containing every disallowed character.
start
       The position in subject to
       start searching.
      
       If start is given and is non-negative,
       then strcspn() 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 strcspn() 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 length is given and is negative,
       then subject will be examined from the
       starting position up to length
       characters from the end of subject.
      
   Returns the length of the initial segment of subject
   which consists entirely of characters not in mask.
  
Note:
When a
startparameter is set, the returned length is counted starting from this position, not from the beginning ofsubject.
Example #1 strcspn() example
<?php
$a = strcspn('abcd',  'apple');
$b = strcspn('abcd',  'banana');
$c = strcspn('hello', 'l');
$d = strcspn('hello', 'world');
$e = strcspn('abcdhelloabcd', 'abcd', -9);
$f = strcspn('abcdhelloabcd', 'abcd', -9, -5);
var_dump($a);
var_dump($b);
var_dump($c);
var_dump($d);
var_dump($e);
var_dump($f);
?>
The above example will output:
int(0) int(0) int(2) int(2) int(5) int(4)
Note: This function is binary-safe.