function convertToURL($text) {
$text = preg_replace("/([a-zA-Z]+:\/\/[a-z0-9\_\.\-]+"."[a-z]{2,6}[a-zA-Z0-9\/\*\-\_\?\&\%\=\,\+\.]+)/"," <a href=\"$1\" target=\"_blank\">$1</a>", $text);
$text = preg_replace("/[^a-z]+[^:\/\/](www\."."[^\.]+[\w][\.|\/][a-zA-Z0-9\/\*\-\_\?\&\%\=\,\+\.]+)/"," <a href="\\" target="\">$1</a>", $text);
$text = preg_replace("/([\s|\,\>])([a-zA-Z][a-zA-Z0-9\_\.\-]*[a-z" . "A-Z]*\@[a-zA-Z][a-zA-Z0-9\_\.\-]*[a-zA-Z]{2,6})" . "([A-Za-z0-9\!\?\@\#\$\%\^\&\*\(\)\_\-\=\+]*)" . "([\s|\.|\,\<])/i", "$1<a href=\"mailto:$2$3\">$2</a>$4",
$text);
return $text;
}

Convert strings into clickable url

PHP