The basic function of this is to find any URLs in the block of text and turn them into hyperlinks.

It will only find URLs if they are properly formatted, meaning they have a www, http, https, ftp or ftps.

function textTohyperlink($text) {
    // The Regular Expression filter
    $reg_exUrl = "/((((http|https|ftp|ftps)\:\/\/)|www\.)[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,4}(\/\S*)?)/";

    // Check if there is a url in the text
    if(preg_match_all($reg_exUrl, $text, $url)) {
           // make the urls hyper links
           $matches = array_unique($url[0]);
           foreach($matches as $match) {
                $replacement = "<a href=".$match." target='_blank' rel='nofollow'>{$match}</a>";
                $text = str_replace($match,$replacement,$text);
           }
           return nl2br($text);
    } else {
           // if no urls in the text just return the text
           return nl2br($text);
    }
}

$text = "The text you want to filter goes here. http://hkpatel201.blogspot.com";
echo textTohyperlink($text);