I have been working on a project where sometimes I would have to get the domain from the site’s url so I can allow access to certain part of the site. Other times, I have parse the domain from referral url to see where the users are coming from.

Rather than writing two different php functions to get the domain name, I wanted to use one php function to get the job done fast.

Get Domain Name Function

/******[Get Main Domain URL Name - Start]******/

function GetDomainName($url)
{
    $host = @parse_url($url, PHP_URL_HOST);
    // If the URL can't be parsed, use the original URL
    // Change to "return false" if you don't want that
    if (!$host)
        $host = $url;
    // The "www." prefix isn't really needed if you're just using
    // this to display the domain to the user
    if (substr($host, 0, 4) == "www.")
        $host = substr($host, 4);
    // You might also want to limit the length if screen space is limited
    if (strlen($host) > 50)
        $host = substr($host, 0, 47) . '...';
    return $host;
}
/******[Get Main Domain URL Name - End]******/

How Get Domain Name From PHP Function

To use this function, call it like any other php function.

Let’s suppose you want parse the domain name from a string, you would call the function like this:

$URL = “http://codewithmark.com/93/how-to-submit-a-wordpress-plugin/”;

Echo GetDomainName($URL);

//Result will be:

Codewithmark.com

Or to get the domain name from Referral URL you would call the function like this:

//get referrer

$RefURL =$_SERVER['HTTP_REFERER'];

Echo GetDomainName($RefURL);

If your referral site is – “http://codewithmark.com/how-to-submit-a-wordpress-plugin” 

Result will be: codewithmark.com

Get Subdomain Name Of A URL

This function works great with subdomains as well.

For example, if your subdomain url is - http://demo.codewithmark.com/2015-10-26_KeyWordSpy/

It will return, demo.codewithmark.com

As you can see, how useful this php function could be in your web programming projects.