ereg_replace — Replace regular expression

ereg_replace — Replace regular expression
This function scans string for matches to pattern , then replaces the matched text
with replacement
string ereg_replace ( string $pattern , string $replacement , string $string )

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.
Example#1

$str= "This is a test";
echo str_replace(" is", " was", $str);
echo ereg_replace("( )is", "\\1was", $str);
echo ereg_replace("(( )is)", "\\2was", $str);
?>
prints "This was a test" three times:
Example#2

$s = "Coding PHP is fun.";
$pattern = "(.*)PHP(.*)";
$replacement = " They say \\1other languages\\2";
print ereg_replace($pattern, $replacement, $s);
?>

Output:
They say Coding other languages is fun.
Explanation:
"PHP" is replaced with "other languages", and the sentence is changed a little, using \1 and \2 to access the parts within parentheses.


Example#3
Replace URLs with links

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