How to check the correct domain name and subdomain in php

Question

How to remove www and confirm a valid domain name.

Valid Domain

domain.com
subdomain.domain.com
sub-domain.domain.com

Invalid Domain

www.domain.com
www.subdomain.domain.com
http://www.domain.com/
http://www.subdomain.com/
www.domain.com/folder/

How is the code?

$domain ='www.domain.com/folder/';
if() {
// validate here
}

Answer 1

Manually delete www first. then just make sure it is in the form of domain.tld or something.domain.tld

$domain = str_replace('www.','',$domain);

if(preg_match('/([a-zA-Z0-9\-_]+\.)?[a-zA-Z0-9\-_]+\.[a-zA-Z]{2,5}/',$domain)) //valid domain

Answer 2

Take a look at the http://framework.zend.com/apidoc/core/Zend_Validate/Zend_Validate_Hostname.html ( Zend_Validate_Hostname) class. I think you can use it outside of the Zend Framework with little tweaking.

Answer 3

$url = "http://stackoverflow.com/";
if (preg_match('/^(http|https|ftp)://([A-Z0-9][A-Z0-9_-]*(?:.[A-Z0-9][A-Z0-9_-]*)+):?(d+)?/?/i', $url)) {
    echo "Your url is ok.";
} else {
    echo "Wrong url.";
}