在php中清理网址

Question

I am trying to make a user submit link box. I've been trying all day and can't seem to get it working.

The goal is to make all of these into example.com... (ie. remove all stuff before the top level domain)

Input is $url =

Their are 4 types of url:

www.example.com...
example.com...
http://www.example.com...
http://example.com...

Everything I make works on 1 or 2 types, but not all 4.

How one can do this?

Answer 1

You can use parse_url for that. For example:

function parse($url) {
    $parts = parse_url($url);
    if ($parts === false) {
        return false;
    }
    return isset($parts['scheme']) 
            ? $parts['host'] 
            : substr($parts['path'], 0, strcspn($parts['path'], '/'));
}

This will leave the "www." part if it already exists, but it's trivial to cut that out with e.g. str_replace. If the url you give it is seriously malformed, it will return false.

Update (an improved solution):

I realized that the above would not work correctly if you try to trick it hard enough. So instead of whipping myself trying to compensate if it does not have a scheme, I realized that this would be better:

function parse($url) {
    $parts = parse_url($url);
    if ($parts === false) {
        return false;
    }
    if (!isset($parts['scheme'])) {
        $parts = parse_url('http://'.$url);
    }
    if ($parts === false) {
        return false;
    }

    return $parts['host'];
}