IsValidIPv6Address

IsValidIPv6Address.cs

public static bool IPv6Check(string input)
{
    if (string.IsNullOrWhiteSpace(input))
    {
        return false;
    }

    if (input.IndexOf("::") != input.LastIndexOf("::")) // 'The "::" can only appear once in an address.'
    {
        return false;
    }

    string[] parts = input.Split(new char[] { ':' });
    int partCount = parts.Length;

    if (partCount < 3 || partCount > 8) // From "::" to  "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"
    {
        return false;
    }

    UInt16 intValue = UInt16.MaxValue;
    foreach (string part in parts)
    {
        if (part == "") { continue; } // If you dont want addresses like "::" to be a legal address, remove this line
        if (!UInt16.TryParse(part, System.Globalization.NumberStyles.AllowHexSpecifier, System.Globalization.NumberFormatInfo.InvariantInfo, out intValue)) // This ensures that no part has a numeric value greater than (2^16)-1 or FFFF in hexadecimal
        {
            return false;
        }
    }

    return true;
}