What are the potential system- and/or version-dependent issues with using ip2long as a validator in PHP?

When using ip2long as a validator in PHP, one potential issue is that it may return false for invalid IP addresses on certain systems or PHP versions. To solve this issue, you can use the filter_var function with the FILTER_VALIDATE_IP flag instead, which provides a more reliable validation method across different systems and PHP versions.

function validateIP($ip) {
    return filter_var($ip, FILTER_VALIDATE_IP) !== false;
}

// Example usage
$ip = "192.168.1.1";
if(validateIP($ip)) {
    echo "Valid IP address";
} else {
    echo "Invalid IP address";
}