Compzone.Org :: Podręcznik PHP :: preg_replace_callback

Podręcznik PHP
Poprzedni		Następny

preg_replace_callback

(PHP 4 >= 4.0.5, PHP 5)

preg_replace_callback -- Perform a regular expression search and replace using a callback

Description

mixed preg_replace_callback ( mixed pattern, callback callback, mixed subject [, int limit [, int &count]] )

The behavior of this function is almost identical to preg_replace(), except for the fact that instead of replacement parameter, one should specify a callback that will be called and passed an array of matched elements in the subject string. The callback should return the replacement string. See preg_replace() for description of other parameters.

Przykład 1. preg_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 preg_replace_callback(


                            "|(\d{2}/\d{2}/)(\d{4})|",


                            "next_year",

                            $text);
// result is:

                // April fools day is 04/01/2003

                // Last christmas was 12/24/2002
?>

You'll often need the callback function for a preg_replace_callback() in just one place. In this case you can use create_function() to declare an anonymous function as callback within the call to preg_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 functions name not used anywhere else.

Przykład 2. preg_replace_callback() and create_function()

<?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|',


                        create_function(

                            // single quotes are essential here,


                            // or alternative escape all $ as \$


                            '$matches',

                            'return strtolower($matches[0]);'


                        ),

                        $line

                    );

                    echo $line;

                }
fclose($fp);
?>

Notatka: count parameter is available since PHP 5.1.0.

See also preg_replace(), create_function(), i informacje o typie callback.

Poprzedni	Spis treści	Następny
preg_quote	Początek rozdziału	preg_replace