PREG_REPLACE(3) 							 1							   PREG_REPLACE(3)

preg_replace - Perform a regular expression search and replace

SYNOPSIS

       mixed preg_replace (mixed  $pattern, mixed  $replacement, mixed	$subject, [int	$limit = -1], [int  &$count])

DESCRIPTION

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

PARAMETERS

	      o $pattern
		- The pattern to search for. It can be either a string or an array with strings.  Several PCRE modifiers are also available.

	      o $replacement
		-  The	string or an array with strings to replace. If this parameter is a string and the $pattern parameter is an array, all pat-
		terns will be replaced by that string. If both $pattern and $replacement parameters are arrays, each $pattern will be replaced	by
		the  $replacement  counterpart.  If there are fewer elements in the $replacement array than in the $pattern array, any extra $pat-
		terns will be replaced by an empty string. $replacement may contain references of the form \ n or (since PHP 4.0.4) $ n, with the
		latter form being the preferred one. Every such reference will be replaced by the text captured by the n'th parenthesized pattern.
		n can be from 0 to 99, and \0 or $0 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. To use backslash in replacement, it must be doubled (
		"\\" PHP string).  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 \1 notation for your backrefer-
		ence.  \11, for example, would confuse preg_replace(3) since it does not know whether you want the \1 backreference followed	by
		a  literal  1, or the \11 backreference followed by nothing. In this case the solution is to use ${1}1. This creates an isolated
		$1 backreference, leaving the 1 as a literal.  When using the deprecated e 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 backref-
		erence usage with either single or double quotes (e.g.	'strlen('$1')+strlen("$2")'). Make sure you are aware  of  PHP's  string
		syntax to know exactly how the interpreted string will look.

	      o $subject
		- The string or an array with strings to search and replace.  If $subject is an array, then the search and replace is performed on
		every entry of $subject, and the return value is an array as well.

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

	      o $count
		- If specified, this variable will be filled with the number of replacements done.

RETURN VALUES

       preg_replace(3) returns an array if the $subject parameter is an array, or a string otherwise.

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

ERRORS
/EXCEPTIONS
	As of PHP 5.5.0 E_DEPRECATED level error is emitted when passing in the "e" modifier. As of PHP 7.0.0 E_WARNING is emited  in	this  case
       and "e" modifier has no effect.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 7.0.0	|						    |
       |	|						    |
       |	|  Support  for  the  /e modifier has been removed. |
       |	| Use preg_replace_callback(3) instead. 	    |
       |	|						    |
       | 5.5.0	|						    |
       |	|						    |
       |	|  The	 /e    modifier    is	 deprecated.	Use |
       |	| preg_replace_callback(3)    instead.	  See	the |
       |	| PREG_REPLACE_EVAL  documentation  for  additional |
       |	| information about security risks.		    |
       |	|						    |
       | 5.1.0	|						    |
       |	|						    |
       |	|	      Added the $count parameter	    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      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);
	      ?>

	      The above example will output:

	      April1,2003

       Example #2

	      Using indexed arrays with preg_replace(3)

	      <?php
	      $string = 'The quick brown fox jumped 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 above example will output:

	      The bear black slow jumped over the lazy dog.

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

	      <?php
	      ksort($patterns);
	      ksort($replacements);
	      echo preg_replace($patterns, $replacements, $string);
	      ?>

	      The above example will output:

	      The slow black bear jumped over the lazy dog.

       Example #3

	      Replacing several values

	      <?php
	      $patterns = array ('/(19|20)(d{2})-(d{1,2})-(d{1,2})/',
				 '/^s*{(w+)}s*=/');
	      $replace = array ('3/4/12', '$1 =');
	      echo preg_replace($patterns, $replace, '{startDate} = 1999-5-27');
	      ?>

	      The above example will output:

	      $startDate = 5/27/1999

       Example #4

	      Strip whitespace

	       This example strips excess whitespace from a string.

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

       Example #5

	      Using the $count parameter

	      <?php
	      $count = 0;

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

	      The above example will output:

	      xp***to
	      3

NOTES

       Note

	       When  using arrays with $pattern and $replacement, the keys are processed in the order they appear in the array. This is not neces-
	      sarily the same as the numerical index order. If you use indexes to identify which $pattern should be replaced  by  which  $replace-
	      ment, you should perform a ksort(3) on each array prior to calling preg_replace(3).

SEE ALSO

       PCRE Patterns, preg_quote(3), preg_filter(3), preg_match(3), preg_replace_callback(3), preg_split(3), preg_last_error(3).

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