mb_ereg_replace_callback

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

&reftitle.description; ``string``false``null```mb_ereg_replace_callback` `string` `pattern` `callable` `callback` `string` `string` ``string``null```options`&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`.

&reftitle.parameters;

`pattern`

- The regular expression pattern.

  Multibyte characters may be used in `pattern`.

`callback`

- 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.

`string`

- The `string` being checked.

`options`

- The search option. See `mb_regex_set_options` for explanation.

&reftitle.returnvalues;

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

&reftitle.changelog;

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

&reftitle.examples;

### `mb_ereg_replace_callback` example

    <?php
    // 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);
    }
    echo mb_ereg_replace_callback(
                "(\d{2}/\d{2}/)(\d{4})",
                "next_year",
                $text);

    ?>

&example.outputs;

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

### `mb_ereg_replace_callback` using anonymous function

    <?php
    // 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";

    echo mb_ereg_replace_callback(
                "(\d{2}/\d{2}/)(\d{4})",
                function ($matches) {
                   return $matches[1].($matches[2]+1);
                },
                $text);
    ?>

&reftitle.notes; ¬e.mbstring.encoding.internal;
&reftitle.seealso;

- `mb_regex_encoding`
- `mb_ereg_replace`
- Anonymous functions