preg_replace

preg_replace

Perform a regular expression search and replace

 **preg_replace**  $pattern  $replacement  $subject int $limit int $count

Searches for matches to and replaces them with . subject``pattern``replacement

To match an exact string, rather than a pattern, consider using or instead of this function. str_replace``str_ireplace

patternThe pattern to search for. It can be either a string or an array with strings.

   Several 
   are also available.
  PCRE modifiers

replacement The string or an array with strings to replace. If this parameter is a string and the parameter is an array, all patterns will be replaced by that string. If both and parameters are arrays, each will be replaced by the counterpart. If there are fewer elements in the array than in the array, any extra s will be replaced by an empty string. pattern``pattern``replacement``pattern``replacement``replacement``pattern``pattern

    may contain references of the form
    or
   , with the latter form
   being the preferred one. Every such reference will be replaced by the text
   captured by the 'th parenthesized pattern.
    can be from 0 to 99, and
    or  refers to the text matched
   by the whole pattern. Opening parentheses are counted from left to right
   (starting from 1) to obtain the number of the capturing subpattern.
   Note that backslashes in string literals may require to be escaped.
  `replacement``\n``$n``\0``$0`


   When working with a replacement pattern where a backreference is 
   immediately followed by another number (i.e.: placing a literal number
   immediately after a matched pattern), you cannot use the familiar 
    notation for your backreference.  
   , for example, would confuse
    since it does not know whether you
   want the  backreference followed by a literal 
   , or the  backreference
   followed by nothing.  In this case the solution is to use 
   .  This creates an isolated
    backreference, leaving the 
   as a literal.
  `\1``\11``preg_replace``\1``1``\11``${1}1``$1``1`


   When using the deprecated  modifier, this function escapes
   some characters (namely , ,
    and NULL) in the strings that replace the
   backreferences. This is done to ensure that no syntax errors arise
   from backreference usage with either single or double quotes (e.g.
   ). Make sure you are
   aware of PHP's  to know exactly how the interpreted string will look.
  `e``'``"``\``'strlen(\'$1\')+strlen("$2")'`string
   syntax

subjectThe string or an array with strings to search and replace.

   If  is an array, then the search and
   replace is performed on every entry of ,
   and the return value is an array as well.
  `subject``subject`


   If the  array is associative, keys
   will be preserved in the returned value.
  `subject`

limit The maximum possible replacements for each pattern in each string. Defaults to (no limit). subject``-1

countIf specified, this variable will be filled with the number of replacements done.

returns an array if the
parameter is an array, or a string

otherwise. preg_replace``subject

If matches are found, the new will be returned, otherwise will be returned unchanged or null if an error occurred. subject``subject

Using the "\e" modifier is an error; an is emitted in this case. E_WARNING

Voorbeeld: Using backreferences followed by numeric literals

<?php
$string = 'April 15, 2003';
$pattern = '/(\w+) (\d+), (\d+)/i';
$replacement = '${1}1,$3';
echo preg_replace($pattern, $replacement, $string);
?>

April1,2003

**Voorbeeld: Using indexed arrays with **

<?php
$string = 'The quick brown fox jumps over the lazy dog.';
$patterns = array();
$patterns[0] = '/quick/';
$patterns[1] = '/brown/';
$patterns[2] = '/fox/';
$replacements = array();
$replacements[2] = 'bear';
$replacements[1] = 'black';
$replacements[0] = 'slow';
echo preg_replace($patterns, $replacements, $string);
?>

The bear black slow jumps over the lazy dog.

By ksorting patterns and replacements, we should get what we wanted.

<?php
$string = 'The quick brown fox jumps over the lazy dog.';
$patterns = array();
$patterns[0] = '/quick/';
$patterns[1] = '/brown/';
$patterns[2] = '/fox/';
$replacements = array();
$replacements[2] = 'bear';
$replacements[1] = 'black';
$replacements[0] = 'slow';
ksort($patterns);
ksort($replacements);
echo preg_replace($patterns, $replacements, $string);
?>

The slow black bear jumps over the lazy dog.

Voorbeeld: Replacing several values

<?php
$patterns = array ('/(19|20)(\d{2})-(\d{1,2})-(\d{1,2})/',
                   '/^\s*{(\w+)}\s*=/');
$replace = array ('\3/\4/\1\2', '$\1 =');
echo preg_replace($patterns, $replace, '{startDate} = 1999-5-27');
?>

$startDate = 5/27/1999

Voorbeeld: Strip whitespace

This example strips excess whitespace from a string.

<?php
$str = 'foo   o';
$str = preg_replace('/\s\s+/', ' ', $str);
// This will be 'foo o' now
echo $str;
?>

Voorbeeld: Using the parameter

<?php
$count = 0;

echo preg_replace(array('/\d/', '/\s/'), '*', 'xp 4 to', -1 , $count);
echo $count; //3
?>

xp***to
3

Opmerking: > When using arrays with and , the keys are processed in the order they appear in the array. This is the same as the numerical index order. If you use indexes to identify which should be replaced by which , you should perform a on each array prior to calling . pattern``replacementnot necessarilypattern``replacement``ksort``preg_replace

Opmerking: > When both and are arrays, matching rules will operate sequentially. That is, the second / pair will operate on the string that results from the first / pair, not the original string. If you want to simulate replacements operating in parallel, such as swapping two values, replace one pattern by an intermediary placeholder, then in a later pair replace that intermediary placeholder with the desired replacement. pattern``replacement``pattern``replacement``pattern``replacement

<?php
$p = array('/a/', '/b/', '/c/');
$r = array('b', 'c', 'd');
print_r(preg_replace($p, $r, 'a'));
// prints d
?>

PCRE Patternspreg_quote``preg_filter``preg_match``preg_replace_callback``preg_split``preg_last_error``str_replace