PHP str_replace() Function

Replace the characters "world" in the string "Hello world!" with "Peter":

<?php
echo str_replace("world","Peter","Hello world!");
?>

Definition and Usage

The str_replace() function replaces some characters with some other characters in a string.

This function works by the following rules:

If the string to be searched is an array, it returns an array
If the string to be searched is an array, find and replace is performed with every array element
If both find and replace are arrays, and replace has fewer elements than find, an empty string will be used as replace
If find is an array and replace is a string, the replace string will be used for every find value

Note: This function is case-sensitive. Use the str_ireplace() function to perform a case-insensitive search.

Note: This function is binary-safe.

str_replace( find,replace,string,count)

Parameter	Description
find	Required. Specifies the value to find
replace	Required. Specifies the value to replace the value in find
string	Required. Specifies the string to be searched
count	Optional. A variable that counts the number of replacements

Return Value:	Returns a string or an array with the replaced values
PHP Version:	4+
Changelog:	The count parameter was added in PHP 5.0 Before PHP 4.3.3, this function experienced trouble when using arrays as both find and replace parameters, which caused empty find indexes to be skipped without advancing the internal pointer on the replace array. Newer versions will not have this problem. As of PHP 4.0.5, most of the parameters can now be an array

Using str_replace() with an array and a count variable:

<?php
$arr = array("blue","red","green","yellow");
print_r(str_replace("red","pink",$arr,$i));
echo "Replacements: $i";
?>

Using str_replace() with fewer elements in replace than find:

<?php
$find = array("Hello","world");
$replace = array("B");
$arr = array("Hello","world","!");
print_r(str_replace($find,$replace,$arr));
?>