Question

I am currently working on a C# project where I need to validate the text that a user has entered into a text box.

One of the validations required is that it checks to ensure that an IP address has been entered correctly.

How would I go about doing this validation of the IP address.

Thanks for any help you can provide.

Answer 1

It seems that you are only concerned with validating IPv4 IP Address strings in X.X.X.X format. If so, this code is straight forward for that task:

string ip = "127.0.0.1";
string[] parts = ip.Split('.');
if (parts.Length < 4)
{
    // not a IPv4 string in X.X.X.X format
}
else
{
    foreach(string part in parts)
    {
        byte checkPart = 0;
        if (!byte.TryParse(part, out checkPart))
        {
            // not a valid IPv4 string in X.X.X.X format
        }
    }
    // it is a valid IPv4 string in X.X.X.X format
}