using System;

public class Program

{

    public static void Main()

    {

        string case1 = null;

        string case2 = "";

        string case3 = " ";

        Console.WriteLine("string test using IsNullOrEmpty()");

        Console.WriteLine($" * case1 (null): {string.IsNullOrEmpty(case1)}");

        Console.WriteLine($" * case2 (\"\"): {string.IsNullOrEmpty(case2)}");

        Console.WriteLine($" * case3 (\" \"): {string.IsNullOrEmpty(case3)}");

        Console.WriteLine("\nstring test using IsNullOrWhiteSpace()");

        Console.WriteLine($" * case1 (null): {string.IsNullOrWhiteSpace(case1)}");

        Console.WriteLine($" * case2 (\"\"): {string.IsNullOrWhiteSpace(case2)}");

        Console.WriteLine($" * case3 (\" \"): {string.IsNullOrWhiteSpace(case3)}");

    }

}