(PHP 4, PHP 5)

ereg_replaceReplace regular expression


This function was DEPRECATED in PHP 5.3.0, and REMOVED in PHP 7.0.0.

Alternatives to this function include:


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

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



A POSIX extended regular expression.


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.


The input string.

Return Values

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


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

Example #1 ereg_replace() example


$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

/* 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

$text = ereg_replace("[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]",
                     '<a href="\\0">\\0</a>', $text);

See Also

  • ereg() - Regular expression match
  • eregi() - Case insensitive regular expression match
  • eregi_replace() - Replace regular expression case insensitive
  • str_replace() - Replace all occurrences of the search string with the replacement string
  • preg_replace() - Perform a regular expression search and replace
  • quotemeta() - Quote meta characters

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