preg_replace

Name:preg_replace

Category:Regular processing PCRE

Programming Language:php

One-line Description:Returns a string where the pattern match is replaced by a substring in the given string.

Definition and usage

preg_replace() function returns a string or array of strings where all matches to the pattern or pattern list found in the input are replaced with substrings.

This function is used in three different ways:

A pattern and a replacement string. The match of the pattern will be replaced by the replacement string.
A pattern array and a replacement string. Any pattern in the matching array will be replaced by the replacement string.
An array of pattern and an array of replacement strings. The matches for each pattern will be replaced by strings at the same position in the replace string array. If no item is found at that position in the replacement array, the match will be replaced with an empty string.

The replacement string can contain backward references in the form of \n or n, where n is the index of the group in the pattern. In the returned string, instances of \n and n will be replaced by the substrings that match the group, or, if \0 or $0 is used, they will be replaced by the entire expression.

Note: For each input string, the function evaluates the pattern in the given order. The result of evaluating the first pattern on the string will be used as the input string for the second pattern, and so on. This can lead to unexpected behavior.

Example

Using case-insensitive regular expressions, replace "Microsoft" with "W3School" in the string:

 <?php
$str = 'Visit Microsoft!' ;
$pattern = '/microsoft/i' ;
echo preg_replace ( $pattern , 'W3School' , $str ) ;
?>

Try it yourself

grammar

 preg_replace ( patterns , replacements , input , limit , count )

parameter	describe
Patterns	Required. Contains regular expressions or regular expression arrays.
replacements	Required. Replace strings or replace string arrays.
input	Required. A string or array of strings that are replaced on it.
limit	Optional. The default is -1, indicating no limit. Sets the limit on the number of replacements that can be made in each string.
count	Optional. After the function is executed, the variable will contain a number indicating how many replacements have been performed.