Validate IP Address in PHP

PHP - Validate IP Address:

A Valid IP address should be satisfied the below conditions.

1. First part must be > 0.
2. All parts of IP address will be <= 255
3. No 0.0.0.0 match
4. 00, 000 are not allowed in pairs if first digit starts with 0
5. allowed for 0 first digit

The below php function "isValid()" is used to find given ip address is valid or not.
 

function isValidIp ( $ip )
{
    return !preg_match ( '/^([1-9]d|1d{0,2}|2[0-5]{2}).('.
                         '(0|1?d{0,2}|2[0-5]{2}).){2}(0|1?'.
                         'd{0,2}|2[0-5]{2})(:d{2,4})?$/',
                         (string) $ip ) 
                       ? false 
                       : true;
}

$ip="192.168.0.40";

if( isValidIp ( $ip ) )
{
   echo "Valid Ip";
}
else
{
    echo "Ip is Not Valid";
}