regex to validate a domain name

[GUIR]

Hi,

Can someone please let me know the regex usable for validating a domain name ?

it could be

http://xxx.xxxx.xxx
https://xxx.xxxx.xxx
http://xxxx.xxx
https://xxxx.xxx
xxxx.xxx
xxx.xxxx.xxx

In other words with or without protocols and with root domain names or sub domains, it should validate them.

Importantly this is for domain name, not to validating a URL which can have folder paths, file names.

Thank you.

[NogDog]

Untested:

$regexp = '#^(https?://)?[^/.]+(\.[^/.])+/?$#'; 

[GUIR]

hi,

Thanks for the help, but that regex doesnt help.

Here are the search conditions

may or may not contain http:// or https://
may or may not contain www part
may or may not contain sub domain part
must have host part
there may be trailing / after the domain
no folder paths or file names

Best Regards

[thraddash]

How about this...

function checkDomain($domain)
{
    if (preg_match('/(^(https?):\/\/|^)(([^\.]+)\.([^\.]+\.[^\/$]+)|([^\.]+\.[^\/$]+))\/?$/', $domain, $matches)) {

        echo
            '<b>' . $domain . '</b><br />' .
            'Protocol: <b>'   . ($matches[2] ? $matches[2] : 'None') . '</b><br />' .
            'Sub-Domain: <b>' . ($matches[4] ? $matches[4] : 'None') . '</b><br />' .
            'Domain: <b>'     . ($matches[5] ? $matches[5] : $matches[6]) . '</b><br />' .
            '<br />';

    } else {
        echo $domain . ' - INVALID<br /><br />';
    }
}

checkDomain('http://www.domain.com');
checkDomain('https://www.domain.com/');
checkDomain('www.domain.com/');
checkDomain('https://domain.com/file');
checkDomain('https://domain.com'); 

[GUIR]

Hi,

Thanks it works fine.

Best Regards

[criterion9]

You could also look at checkdnsrr.

[NogDog]

hi,

Thanks for the help, but that regex doesnt help.

Here are the search conditions

may or may not contain http:// or https://
may or may not contain www part
may or may not contain sub domain part
must have host part
there may be trailing / after the domain
no folder paths or file names

Best Regards

It was missing one "+" character:

'#^(https?://)?[^/.]+(\.[^/.]+)+/?$#'

Test:

<?php
$data = array(
   'http://xxx.xxxx.xxx',
   'https://xxx.xxxx.xxx/',
   'http://xxxx.xxx/',
   'https://xxxx.xxx',
   'xxxx.xxx',
   'xxx.xxxx.xxx',
   'http://xxx.xxx.xxx/no_good',
   'not_a_domain'
);
$regexp = '#^(https?://)?[^/.]+(\.[^/.]+)+/?$#';
foreach($data as $test) {
   echo "<p>$test: ";
   echo (preg_match($regexp, $test)) ? "valid" : "NOT valid";
   echo "</p>\n";
}

Output:

http://xxx.xxxx.xxx: valid

https://xxx.xxxx.xxx/: valid

http://xxxx.xxx/: valid

https://xxxx.xxx: valid

xxxx.xxx: valid

xxx.xxxx.xxx: valid

http://xxx.xxx.xxx/no_good: NOT valid

not_a_domain: NOT valid

[GUIR]

Thank you ..