Program.cs

using System;

namespace String_IsNullOrEmpty_Test
{
    class Program
    {
        static void Main( string [] args ) {
            string test1 = null;
            string test2 = string.Empty;
            string test3 = "";

            Console.WriteLine( "Is Null: " + (test1 == null));
            Console.WriteLine( "Is Null: " + (test2 == null));
            Console.WriteLine( "Is Null: " + (test3 == null));

            Console.WriteLine( "Is Empty: " + (test1 == String.Empty));
            Console.WriteLine( "Is Empty: " + (test2 == String.Empty));
            Console.WriteLine( "Is Empty: " + (test3 == String.Empty));

            Console.WriteLine( "IsNullOrEmpty: " + String.IsNullOrEmpty( test1 ) );
            Console.WriteLine( "IsNullOrEmpty: " + String.IsNullOrEmpty( test2 ) );
            Console.WriteLine( "IsNullOrEmpty: " + String.IsNullOrEmpty( test3 ) );
        }
    }
}