substr_replace()

substr_replace() — Replace text within a portion of a string.

Built-in function of PHP 8.5. The manual lists it as available in PHP 4, PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

substr_replace() replaces a copy of string delimited by the offset and (optionally) length parameters with the string given in replace.

Signature

Parameters

Parameter	Type	What it takes
$string	array\|string	The input string.
$replace	array\|string	The replacement string.
$offset	array\|int	If offset is non-negative, the replacing will begin at the offset'th offset into string.
$length	array\|int\|null	If given and is positive, it represents the length of the portion of string which is to be replaced. If it is negative, it represents the number of characters from the end of string at which to stop replacing. If it is not given, then it will default to strlen( string ); i.e. end the replacing at the end of string. Of course, if length is zero then this function will have the effect of inserting replace into string ...

Return value

The result string is returned. If string is an array then array is returned.

Example

A runnable snippet:

$var = 'ABCDEFGH:/MNRPQR/'; echo "Original: $var<hr />\n"; /* These two examples replace all of $var with 'bob'. */ echo substr_replace($var, 'bob', 0) . " \n"; echo substr_replace($var, 'bob', 0, strlen($var)) . " \n"; /* Insert 'bob' right at the beginning of $var. */ echo substr_replace($var, 'bob', 0, 0) . " \n"; /* These next two replace 'MNRPQR' in $var with 'bob'. */ echo substr_replace($var, 'bob', 10, -1) . " \n"; echo substr_replace($var, 'bob', -7, -1) . " \n"; /* Delete 'MNRPQR' from $var. */ echo substr_replace($var, '', 10, -1) . " \n";

Changelog

Version	Change
8.0.0	length is nullable now.