从URL获取最后11个字符

Question

I got this code:

if(preg_match("/^(?:https?:\/\/)?(?:www\.)?youtu(.be\/|be\.com\/watch\?v=)(\w{11})$/", $url)){
        preg_match("/^(?:https?:\/\/)?(?:www\.)?youtu(.be\/|be\.com\/watch\?v=)(\w{11})$/", $url, $matches);
        $vid = str_replace(' ', '', $matches[0]);
}

That pretty much checks if the URL is a Youtube video. How do I assign the last 11 characters from the URL to the $vid variable?

Example:

URL: https://www.youtube.com/watch?v=ASDASDASDAS

$vid = ASDASDASDAS

Answer 1

First, you don't want to check for the last 11 characters, because the video ID might be changed any time to a different length. What you should always do is make something flexible enough. So in this case, you should check for ?.*v=([^&]+), since that will get the match until the next &. So your code would look like this:

//make this a variable, since you're using it multiple times.
$re = "/^(?:https?:\/\/)?(?:www\.)?youtu(.be|be\.com)\/watch\?.*?v=([^&#]+).*$/";
if (preg_match($re, $url)){
        preg_match($re, $url, $matches);
        $vid = $matches[2]; //the 2nd group in the match, so the 2nd set of ()s
}

In that code, video urls that contain other URL parameters will also still work, and it's much more flexible with the length of the video ID.

Demo - look to the right where it says 2., it will mention the video ID there (which is what's put inside $vid).