Check the syntax of a Internet domain

[fabiuz]

Hi,

I need to check if the syntax of a tyed Internet domain is correct.

I was thinking to use something similar to:

$check_domain = ereg("[a-zA-Z0-9][-][a-zA-Z0-9]{3,63})$", $domain);

but I don't know how to use the brackets and the elements inside.

Where can I find informations about ?

I need only to check that the name have only letters or numbers or one "-" in any position.

Thank you

Fabio

[chowdary]

Hi,
I am not familiar with Regular Expressions.

This function returns "valid" or "invalid"
(Returns invalid if that string contains any special characters except "." and "-" .ie the string can contain any alphabet or digit or "-" or ".")

function checkDomain($domain)
{
$domain_str=strtolower($domain);
$flag="valid";
for($i=0;$i<strlen($domain_str);$i++)
{
$nxt_char=substr($domain_str,$i,1);
$nxt_asci=Ord($nxt_char);
if(!($nxt_asci>=48 && $nxt_asci<=57) && !($nxt_asci>=97 && $nxt_asci<=122) &&
$nxt_asci!=45 && $nxt_asci!=46)
{
$flag="invalid";
}
}

     return $flag;

}

[fabiuz]

Thank you for the help,

I have take a to the function, it works pretty fine but it doesn't take care about id the "-" ia at the beginning or at the end of the domain name and also it doesn't take care if you type "--" or ".." two times...

[chowdary]

Hi,
This is the modified one.Test it out

function checkDomain($domain)
{
$domain_str=strtolower($domain);
$flag="valid";
for($i=0;$i<strlen($domain_str);$i++)
{
$nxt_char=substr($domain_str,$i,1);
if($i==0 || $i==strlen($domain_str)-1)
{
if($nxt_char=="-" || $nxt_char=="."){ $flag="invalid";}
}
else
{

$dbl_char=$prev_char.$nxt_char;
$prev_char=$nxt_char;
if($dbl_char=="--" || $dbl_char==".."){$flag="invalid";}
}
$nxt_asci=Ord($nxt_char);
if(!($nxt_asci>=48 && $nxt_asci<=57) && !($nxt_asci>=97 && $nxt_asci<=122) &&
$nxt_asci!=45 && $nxt_asci!=46)
{
$flag="invalid";
}
}
return $flag;
}

Enjoy............

[fabiuz]

Thanks to Sridhar, I have solved with this simple script that does the job in a very easy a quick way:

if(eregi("^{0-9a-z[0-9a-z]$",} $dominio)) {
print "the domain is OK!";
}
else {
print "the domain is NOT ok!";
}

Thank you very much for your help

Fabio