(PHP 5 >= 5.4.1, PHP 7, PHP 8)

mb_ereg_replace_callbackPerform a regular expression search and replace with multibyte support using a callback


    string $pattern,
    callable $callback,
    string $string,
    ?string $options = null
): string|false|null

Scans string for matches to pattern, then replaces the matched text with the output of callback function.

The behavior of this function is almost identical to mb_ereg_replace(), except for the fact that instead of replacement parameter, one should specify a callback.



The regular expression pattern.

Multibyte characters may be used in pattern.


A callback that will be called and passed an array of matched elements in the string string. The callback should return the replacement string.

You'll often need the callback function for a mb_ereg_replace_callback() in just one place. In this case you can use an anonymous function to declare the callback within the call to mb_ereg_replace_callback(). By doing it this way you have all information for the call in one place and do not clutter the function namespace with a callback function's name not used anywhere else.


The string being checked.


The search option. See mb_regex_set_options() for explanation.

Return Values

The resultant string on success, or false on error. If string is not valid for the current encoding, null is returned.


Version Description
8.0.0 options is nullable now.
7.1.0 The function checks whether string is valid for the current encoding.


Example #1 mb_ereg_replace_callback() example

// this text was used in 2002
// we want to get this up to date for 2003
$text = "April fools day is 04/01/2002\n";
$text.= "Last christmas was 12/24/2001\n";
// the callback function
function next_year($matches)
// as usual: $matches[0] is the complete match
// $matches[1] the match for the first subpattern
// enclosed in '(...)' and so on
return $matches[1].($matches[2]+1);


The above example will output:

April fools day is 04/01/2003
Last christmas was 12/24/2002

Example #2 mb_ereg_replace_callback() using anonymous function

// this text was used in 2002
// we want to get this up to date for 2003
$text = "April fools day is 04/01/2002\n";
$text.= "Last christmas was 12/24/2001\n";

function (
$matches) {



The internal encoding or the character encoding specified by mb_regex_encoding() will be used as the character encoding for this function.

See Also

add a note

User Contributed Notes

There are no user contributed notes for this page.
To Top