how to clean link using php

function clickable_link($var)
{
$text = $var;
$text = preg_replace('#(script|about|applet|activex|chrome):#is', "\\1:", $text);
$ret = ' ' . $text;
$ret = preg_replace("#(^|[\n ])([\w]+?://[\w\#$%&~/.\-;:=,?@\[\]+]*)#is", "\\1\\2", $ret);
$ret = preg_replace("#(^|[\n ])((www|ftp)\.[\w\#$%&~/.\-;:=,?@\[\]+]*)#is", "\\1\\2", $ret);
$ret = preg_replace("#(^|[\n ])([a-z0-9&\-_.]+?)@([\w\-]+\.([\w\-\.]+\.)*[\w]+)#i", "\\1\\2@\\3", $ret);
$ret = substr($ret, 1);
return $ret;
}

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