Replace urls in a content

function cleanlinks($var){
if(is_string($var)){
$var = preg_replace("/\n+/", ' ', $var);
$a = preg_match_all('/]*href\s*=\s*([\"\']+)([^\"\'\s>]+?)(\1|>)/i',$var,$matches);
if($a){
foreach ($matches[2] as $url){
$var = str_replace($url, '/', $var);
}
}
}
return $var;
}