convert links into clickable hyperlinks with PHP

<?php
function makeClickableLink($text) {
$text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_+.~#?&//=]+)', '<a href="1">1</a>', $text);
$text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&//=]+)', '1<a href="http://2">2</a>', $text);
$text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})', '<a href="mailto:1">1</a>', $text);
return $text;
}

// Usage

// Email address example
$text = "you@example.com";
echo makeClickableLink($text);

// URL example
$text = "http://www.example.com";
echo makeClickableLink($text);

// FTP URL example
$text = "ftp://ftp.example.com";
echo makeClickableLink($text);
?>