PHP: Replace regular expression

Description

string ereg_replace ( string $pattern , string $replacement , string $string )

This function scans string for matches to pattern , then replaces the matched text with replacement .

Parameters

pattern: A POSIX extended regular expression.
replacement: If pattern contains parenthesized substrings, replacement may contain substrings of the form \\digit, which will be replaced by the text matching the digit'th parenthesized substring; \\0 will produce the entire contents of string. Up to nine substrings may be used. Parentheses may be nested, in which case they are counted by the opening parenthesis.
string: The input string.

Return Values

The modified string is returned. If no matches are found in string , then it will be returned unchanged.

Examples

For example, the following code snippet prints "This was a test" three times:

Example #1 ereg_replace() example


<?php



$string = "This is a test";

echo str_replace(" is", " was", $string);

echo ereg_replace("( )is", "\1was", $string);

echo ereg_replace("(( )is)", "\2was", $string);



?>

One thing to take note of is that if you use an integer value as the replacement parameter, you may not get the results you expect. This is because ereg_replace() will interpret the number as the ordinal value of a character, and apply that. For instance:

Example #2 ereg_replace() example


<?php

/* This will not work as expected. */

$num = 4;

$string = "This string has four words.";

$string = ereg_replace('four', $num, $string);

echo $string;   /* Output: 'This string has   words.' */



/* This will work. */

$num = '4';

$string = "This string has four words.";

$string = ereg_replace('four', $num, $string);

echo $string;   /* Output: 'This string has 4 words.' */

?>

Example #3 Replace URLs with links


<?php

$text = ereg_replace("[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]",

                     "<a href=\"\0\">\0</a>", $text);

?>

Notes

Tip

preg_replace(), which uses a Perl-compatible regular expression syntax, is often a faster alternative to ereg_replace().