Posted by deko on 02/12/07 20:58

Here's a possible way to validate a host's domain name(s):

$invalid = "(~ ` ! @ # $ % ^ & * ( ) _+ = { } [ ] \ | : ; " ' < > , ? /)"
//pseudo code
$url_a = parse_url($url);
$urlHost = $url_a['host'];
$urlHost_a = explode('.',$urlHost);
for ($i = count($urlHost_a) - 2; $i > 0 ; $i--) //skips TLD
{
if (preg_match($invalid, $urlHost_a[$i]))
{
echo 'failed on '.$urlhost_a[$i].'<br>';
}
else
{
echo 'valid domain name(s)<br>';
}
}

Any suggestions on how to construct that $invalid pattern? I'm not sure what
syntakx to use or what characters need to be escaped.

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