Replace YouTube URL in text with its HTML embed code

Question

This function embed youtube videos if found in a string.

My question is what would be the easiest way to only capture the embedded video (the iframe and only the fir

Answer 1

Okay, I think I see what you're trying to accomplish. A user inputs a block of text (some comment or whatever), and you find a YouTube URL in that text and replace it with the actual video embed code.

Here's how I've modified it:

function youtube($string,$autoplay=0,$width=480,$height=390)
{
    preg_match('#(?:http://)?(?:www\.)?(?:youtube\.com/(?:v/|watch\?v=)|youtu\.be/)([\w-]+)(?:\S+)?#', $string, $match);
    $embed = <<<YOUTUBE
        <div align="center">
            <iframe title="YouTube video player" width="$width" height="$height" src="http://www.youtube.com/embed/$match[1]?autoplay=$autoplay" frameborder="0" allowfullscreen></iframe>
        </div>
YOUTUBE;

    return str_replace($match[0], $embed, $string);
}

Since you're already locating the URL with the first preg_match(), there's no need to run another regex function for replacing it. Have it match the entire URL, then do a simple str_replace() of your entire match ($match[0]). The video code is captured in the first subpattern ($match[1]). I'm using preg_match() because you only want to match the first URL found. You'd have to use preg_match_all() and modify the code a bit if you wanted to match all URLs, not just the first.

Here's an explanation of my regular expression:

(?:http://)?    # optional protocol, non-capturing
(?:www\.)?      # optional "www.", non-capturing
(?:
                # either "youtube.com/v/XXX" or "youtube.com/watch?v=XXX"
  youtube\.com/(?:v/|watch\?v=)
  |
  youtu\.be/     # or a "youtu.be" shortener URL
)
([\w-]+)        # the video code
(?:\S+)?        # optional non-whitespace characters (other URL params)