preg_replace_callback

Perform a regular expression search and replace using a callback

 **preg_replace_callback**  $pattern callable $callback  $subject int $limit int $count int $flags

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

patternThe pattern to search for. It can be either a string or an array with strings.

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

  ```php

string **** array $matches





       You'll often need the  function
       for a  in just one place.
       In this case you can use an
        to
       declare the callback within the call to
       . 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.
      `callback``preg_replace_callback`anonymous function`preg_replace_callback`


       
      **Voorbeeld:  and
        anonymous function**

```php
<?php
/* a unix-style command line filter to convert uppercase
 * letters at the beginning of paragraphs to lowercase */
$fp = fopen("php://stdin", "r") or die("can't read stdin");
while (!feof($fp)) {
    $line = fgets($fp);
    $line = preg_replace_callback(
        '|<p>\s*\w|',
        function ($matches) {
            return strtolower($matches[0]);
        },
        $line
    );
    echo $line;
}
fclose($fp);
?>

subjectThe string or an array with strings to search and replace.

limit The maximum possible replacements for each pattern in each string. Defaults to (no limit). subject``-1

countIf specified, this variable will be filled with the number of replacements done.

flags can be a combination of the and flags, which influence the format of the matches array. See the description in for more details. flags``PREG_OFFSET_CAPTURE``PREG_UNMATCHED_AS_NULL``preg_match

returns an array if the
parameter is an array, or a string

otherwise. On errors the return value is null preg_replace_callback``subject

If matches are found, the new subject will be returned, otherwise will be returned unchanged. subject

Voorbeeld: 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 preg_replace_callback(
            "|(\d{2}/\d{2}/)(\d{4})|",
            "next_year",
            $text);

?>

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

Voorbeeld: using recursive structure to handle encapsulated BB code

<?php
$input = "plain [indent] deep [indent] deeper [/indent] deep [/indent] plain";

function parseTagsRecursive($input)
{

    $regex = '#\[indent]((?:[^[]|\[(?!/?indent])|(?R))+)\[/indent]#';

    if (is_array($input)) {
        $input = '<div style="margin-left: 10px">'.$input[1].'</div>';
    }

    return preg_replace_callback($regex, 'parseTagsRecursive', $input);
}

$output = parseTagsRecursive($input);

echo $output;
?>

PCRE Patternspreg_replace_callback_array``preg_quote``preg_replace``preg_last_errorAnonymous functions

Vorige ← preg_replace_callback_array Volgende preg_replace →

preg_replace_callback

preg_replace_callback

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