Convert plain text URLs into HTML hyperlinks in PHP

Here is another solution, This will catch all http/https/www and convert to clickable links.

$url = '~(?:(https?)://([^\s<]+)|(www\.[^\s<]+?\.[^\s<]+))(?<![\.,:])~i'; 
$string = preg_replace($url, '<a href="$0" target="_blank" title="$0">$0</a>', $string);
echo $string;

Alternatively for just catching http/https then use the code below.

$url = '/(http|https|ftp|ftps)\:\/\/[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/\S*)?/';   
$string= preg_replace($url, '<a href="$0" target="_blank" title="$0">$0</a>', $string);
echo $string;

EDIT: The script below will catch all URL types and convert them to clickable links.

$url = '@(http)?(s)?(://)?(([a-zA-Z])([-\w]+\.)+([^\s\.]+[^\s]*)+[^,.\s])@';
$string = preg_replace($url, '<a href="http$2://$4" target="_blank" title="$0">$0</a>', $string);
echo $string;

The new update, If you're having the string strip the (s) then use the below code block, Thanks to @AndrewEllis for pointing this out.

$url = '@(http(s)?)?(://)?(([a-zA-Z])([-\w]+\.)+([^\s\.]+[^\s]*)+[^,.\s])@';
$string = preg_replace($url, '<a href="http$2://$4" target="_blank" title="$0">$0</a>', $string);
echo $string;

Here's a very simple solution for the URL not displaying correctly.

$email = '<a href="mailto:[email protected]">[email protected]</a>';
$string = $email;
echo $string;

It is a very simple fix but you will have to modify it for your own purpose.

I've provided multiple answers as some servers are set up differently, so one answer may work for some but not for others, but I hope the answer(s) work for you and if not then let me know, and hopefully, I can come up with another solution.

There are multiple scripts as some PHP files require different scripts also some servers are set up differently, Plus each has different requirements, Some want just HTTP/S, some want WWW and some want FTP/S, Each one will work depending on how the users own scripts are set up, I provided some text with each one with what they do.

Well, Volomike's answer is much closer. And to push it a bit further, here's what I did for it to disregard the trailing period at the end of the hyperlinks. I also considered URI fragments.

public static function makeClickableLinks($s) {
  return preg_replace('@(https?://([-\w\.]+[-\w])+(:\d+)?(/([\w/_\.#-]*(\?\S+)?[^\.\s])?)?)@', '<a href="$1" target="_blank">$1</a>', $s);
}

Refer http://zenverse.net/php-function-to-auto-convert-url-into-hyperlink/. This is how wordpress solve it

function _make_url_clickable_cb($matches) {
    $ret = '';
    $url = $matches[2];

    if ( empty($url) )
        return $matches[0];
    // removed trailing [.,;:] from URL
    if ( in_array(substr($url, -1), array('.', ',', ';', ':')) === true ) {
        $ret = substr($url, -1);
        $url = substr($url, 0, strlen($url)-1);
    }
    return $matches[1] . "<a href=\"$url\" rel=\"nofollow\">$url</a>" . $ret;
}

function _make_web_ftp_clickable_cb($matches) {
    $ret = '';
    $dest = $matches[2];
    $dest = 'http://' . $dest;

    if ( empty($dest) )
        return $matches[0];
    // removed trailing [,;:] from URL
    if ( in_array(substr($dest, -1), array('.', ',', ';', ':')) === true ) {
        $ret = substr($dest, -1);
        $dest = substr($dest, 0, strlen($dest)-1);
    }
    return $matches[1] . "<a href=\"$dest\" rel=\"nofollow\">$dest</a>" . $ret;
}

function _make_email_clickable_cb($matches) {
    $email = $matches[2] . '@' . $matches[3];
    return $matches[1] . "<a href=\"mailto:$email\">$email</a>";
}

function make_clickable($ret) {
    $ret = ' ' . $ret;
    // in testing, using arrays here was found to be faster
    $ret = preg_replace_callback('#([\s>])([\w]+?://[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]*)#is', '_make_url_clickable_cb', $ret);
    $ret = preg_replace_callback('#([\s>])((www|ftp)\.[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]*)#is', '_make_web_ftp_clickable_cb', $ret);
    $ret = preg_replace_callback('#([\s>])([.0-9a-z_+-]+)@(([0-9a-z-]+\.)+[0-9a-z]{2,})#i', '_make_email_clickable_cb', $ret);

    // this one is not in an array because we need it to run last, for cleanup of accidental links within links
    $ret = preg_replace("#(<a( [^>]+?>|>))<a [^>]+?>([^>]+?)</a></a>#i", "$1$3</a>", $ret);
    $ret = trim($ret);
    return $ret;
}