How to split strings on carriage return with C#?

string[] result = input.Split(new string[] {"\n", "\r\n"}, StringSplitOptions.RemoveEmptyEntries);

This covers both \n and \r\n newline types and removes any empty lines your users may enter.

I tested using the following code:

        string test = "PersonA\nPersonB\r\nPersonC\n";
        string[] result = test.Split(new string[] {"\n", "\r\n"}, StringSplitOptions.RemoveEmptyEntries);
        foreach (string s in result)
            Console.WriteLine(s);

And it works correctly, splitting into a three string array with entries "PersonA", "PersonB" and "PersonC".

Replace any \r\n with \n, then split using \n:

string[] arr = txbUserName.Text.Replace("\r\n", "\n").Split("\n".ToCharArray());