Convert plain text URLs into HTML hyperlinks in PHP

Question

I have a simple commenting system where people can submit hyperlinks inside the plain text field. When I display these records back from the database and into the web page, what RegExp in PHP can I use to convert these links into HTML-type anchor links?

I don't want the algorithm to do this with any other kind of link, just http and https.

sktrdie_50394 · Answer

\1', $text);
        $text = eregi_replace('(((f|ht){1}tps://)[-a-zA-Z0-9@:%_\+.~#?&//=]+)',
                '\1', $text);
        $text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_\+.~#?&//=]+)',
        '\1\2', $text);
        $text = eregi_replace('([_\.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,3})',
        '\1', $text);
        return $text;
}

// Example Usage
echo makeClickableLinks("This is a test clickable link: http://www.websewak.com  You can also try using an email address like test@websewak.com");
?>

user_1564840 · Answer

Try this one:

$s = preg_replace('/(?)(?\s]+)/is', '\1', $s);

It skips the existing links (if we already have a href, it won't add a href inside of a href). Otherwise it will add the a href with blank target.

user_105539 · Answer

public static function makeClickableLinks($s) {
    return preg_replace('@(https?://([-\w\.]+)+(:\d+)?(/([\w/_\.-]*(\?\S+)?)?)?)@', '$1', $s);
}

user_231388 · Answer

I recommend not to do many things on fly like this. I prefer to use simple editor interface like the one used in stackoverflow. It is called Markdown.

user_2100636 · Answer

Finding Plain Text Links inside HTML

I really liked this answer - yet I needed a solution for possible plain text links that are inside very simple HTML text:

I found a really cool site you might like:
www.stackoverflow.com

This meant I needed the regex patterns to ignore the html chars < and >

Regex Adjustment

So I changed parts of the patterns to [^\s\>\<] instead of \S

\S - not white-space; matches any char that is not white-space (tab, space, newline)
[^] - a negated set; matches any char not in the set

My version of the function from this answer

I needed another format in addition to HTML so I separated out the regexes from their replacements to accommodate this.

I also added a way to return just the links/emails found into an array so I can save them as a relationship on my posts (great for making meta cards for them later ...and for analytics!).

UPDATE: Consecutive periods were matching

I was getting matches for text like there...it - So I wanted to ensure I didn't get any matches that included consecutive dots.

Note: To accomplish fixing this, I added an additional format string to undo matching them to avoid having to redo these otherwise reliable url regexes.

/***
 * based on this answer: https://stackoverflow.com/a/49689245/2100636
 *
 * @var $text String
 * @var $format String - html ($0'
        : ($format == 'short' || $returnMatches ? '[link:$0]' : '$0');

    $formatSansProtocol = $format == 'html'
        ? '$0'
        : ($format == 'short' || $returnMatches ? '[link://$0]' : '$0');

    $formatMailto = $format == 'html'
        ? '$1'
        : ($format == 'short' || $returnMatches ? '[mailto:$1]' : '$1');

    $regProtocol = '/(http|https|ftp|ftps)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,}(/[^\<\>\s]*)?/';
    $regSansProtocol = '/(?<=\s|\A|\>)([0-9a-zA-Z\-\.]+\.[a-zA-Z0-9/]{2,})(?=\s|$|\,|\<)/';
    $regEmail = '/([^\s\>\<]+\@[^\s\>\<]+\.[^\s\>\<]+)\b/';
    $consecutiveDotsRegex = $format == 'html'
        ? '/]+[\.]{2,}[^\>]*?>([^\<]*?)/'
        : '/$$link:.*?//([^$$]+[\.]{2,}[^\]]*?)\]/';

    // Protocol links
    $formatString = preg_replace($regProtocol, $formatProtocol, $string);
    // Sans Protocol Links
    $formatString = preg_replace($regSansProtocol, $formatSansProtocol, $formatString); // use formatString from above
    // Email - Mailto - Links
    $formatString = preg_replace($regEmail, $formatMailto, $formatString); // use formatString from above
    // Prevent consecutive periods from getting captured
    $formatString = preg_replace($consecutiveDotsRegex, '$1', $formatString);

    if ($returnMatches) {
        // Find all [x:link] patterns
        preg_match_all('/$$.*?:(.*?)$$/', $formatString, $matches);

        current($matches); // to move pointer onto groups
        return next($matches); // return the groups
    }

    return $formatString;
}

user_1377350 · Answer

 $val) {
        $attr .= ' ' . $key . '="' . htmlentities($val) . '"';
    }
    
    $links = array();
    
    // Extract existing links and tags
    $value = preg_replace_callback('~(.*?|<.*?>)~i', function ($match) use (&$links) { return '<' . array_push($links, $match[1]) . '>'; }, $value);
    
    // Extract text links for each protocol
    foreach ((array)$protocols as $protocol) {
        switch ($protocol) {
            case 'http':
            case 'https':   $value = preg_replace_callback('~(?:(https?)://([^\s<]+)|(www\.[^\s<]+?\.[^\s<]+))(?$link") . '>'; }, $value); break;
            case 'mail':    $value = preg_replace_callback('~([^\s<]+?@[^\s<]+?\.[^\s<]+)(?{$match[1]}") . '>'; }, $value); break;
            case 'twitter': $value = preg_replace_callback('~(?{$match[0]}") . '>'; }, $value); break;
            default:        $value = preg_replace_callback('~' . preg_quote($protocol, '~') . '://([^\s<]+?)(?{$match[1]}") . '>'; }, $value); break;
        }
    }
    
    // Insert all link
    return preg_replace_callback('/<(\d+)>/', function ($match) use (&$links) { return $links[$match[1] - 1]; }, $value);
}

Not my code, I got it from here https://gist.github.com/jasny/2000705

Convert plain text URLs into HTML hyperlinks in PHP

15 Answers

Finding Plain Text Links inside HTML

Regex Adjustment

My version of the function from this answer

UPDATE: Consecutive periods were matching