testnull.cs

using System;

namespace Test
{
    class NullTest
    {
        static int? GetNullableInt()
        {
            return null;
        }

        static string GetStringValue()
        {
            return null;
        }

        static void Main()
        {
            // ?? operator example.
            int? x = null;

            // y = x, unless x is null, in which case y = -1.
            int y = x ?? -1;
            Console.WriteLine(y);

            // Assign i to return value of method, unless
            // return value is null, in which case assign
            // default value of int to i.
            int i = GetNullableInt() ?? default(int);
            Console.WriteLine(i);

            string s = GetStringValue();
            // ?? also works with reference types. 
            // Display contents of s, unless s is null, 
            // in which case display "Unspecified".
            Console.WriteLine(s ?? "Unspecified");
        }
    }
}