PHP Manual: Replace text within a portion of a string

Description

stringarray substr_replace(
    arraystring $string,
    arraystring $replace,
    arrayint $offset,
    arrayintnull $length = null
)

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

Parameters

string

The input string.

An array of strings can be provided, in which case the replacements will occur on each string in turn. In this case, the replace, offset and length parameters may be provided either as scalar values to be applied to each input string in turn, or as arrays, in which case the corresponding array element will be used for each input string.

replace

The replacement string.

offset

If offset is non-negative, the replacing will begin at the offset'th offset into string.

If offset is negative, the replacing will begin at the offset'th character from the end of string.

length

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 at the given offset offset.

Return Values

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

Changelog

Version	Description
8.0.0	`length` is nullable now.

Examples

Example #1 Simple substr_replace examples

<?php
$var = 'ABCDEFGH:/MNRPQR/';
echo "Original: $var<hr />\n";

/* These two examples replace all of $var with 'bob'. */
echo substr_replace($var, 'bob', 0) . "<br />\n";
echo substr_replace($var, 'bob', 0, strlen($var)) . "<br />\n";

/* Insert 'bob' right at the beginning of $var. */
echo substr_replace($var, 'bob', 0, 0) . "<br />\n";

/* These next two replace 'MNRPQR' in $var with 'bob'. */
echo substr_replace($var, 'bob', 10, -1) . "<br />\n";
echo substr_replace($var, 'bob', -7, -1) . "<br />\n";

/* Delete 'MNRPQR' from $var. */
echo substr_replace($var, '', 10, -1) . "<br />\n";
?>

Example #2 Using substr_replace to replace multiple strings at once

<?php
$input = array('A: XXX', 'B: XXX', 'C: XXX');

// A simple case: replace XXX in each string with YYY.
echo implode('; ', substr_replace($input, 'YYY', 3, 3))."\n";

// A more complicated case where each replacement is different.
$replace = array('AAA', 'BBB', 'CCC');
echo implode('; ', substr_replace($input, $replace, 3, 3))."\n";

// Replace a different number of characters each time.
$length = array(1, 2, 3);
echo implode('; ', substr_replace($input, $replace, 3, $length))."\n";
?>

The above example will output:

A: YYY; B: YYY; C: YYY
A: AAA; B: BBB; C: CCC
A: AAAXX; B: BBBX; C: CCC

Notes

Note: This function is binary-safe.

substr_replace