php preg_filter performs a regular expression search and replace

preg_filter
(PHP 5 > = 5.3.0)

preg_filter - performs a regular expression search and replace
mixed preg_filter ( mixed $pattern , mixed $replacement , mixed $subject [, int $limit = -1 [, int &$count ]] )
preg_filter() is equivalent to preg_replace() except that it only returns (possibly converted) results that match the target. Read the preg_replace() documentation for more details on how this function works.

The return value
If subject is 1 array, return 1 array, and otherwise return 1 string.

If no match is found or an error occurs, an empty array is returned when subject is an array, and NULL is otherwise returned.

sample

Example #1 compares the examples of preg_filter() and preg_replace()

 
<?php 
$subject = array('1', 'a', '2', 'b', '3', 'A', 'B', '4'); 
$pattern = array('/\d/', '/[a-z]/', '/[1a]/'); 
$replace = array('A:$0', 'B:$0', 'C:$0'); 

echo "preg_filter returns\n"; 
print_r(preg_filter($pattern, $replace, $subject)); 

echo "preg_replace returns\n"; 
print_r(preg_replace($pattern, $replace, $subject)); 
?> 

The above routine will output:

 
preg_filter returns 
Array 
( 
[0] => A:C:1 
[1] => B:C:a 
[2] => A:2 
[3] => B:b 
[4] => A:3 
[7] => A:4 
) 
preg_replace returns 
Array 
( 
[0] => A:C:1 
[1] => B:C:a 
[2] => A:2 
[3] => B:b 
[4] => A:3 
[5] => A 
[6] => B 
[7] => A:4 
) 

PCRE Patterns preg_replace() - performs the search and replace of a regular expression preg_replace_callback() - performs 1 regular expression search and replaces it with 1 callback preg_grep() - returns an array entry for the matching pattern preg_last_error() - returns the error code generated by the last PCRE regular execution