Nullable Type Variable in C# Language

Introduction

A nullable type variable use to a  hold null value, which provide the c# language. You can not assign a null value directly to a int type. So to make the value type accept a null value, nullable types are used. You cannot create a nullable type based on a reference type because reference types already support the null value.

Example

using System;

namespace null_coalescing_operator_in_c_sharp

{

    class Program

    {

        static void Main(string[] args)

        {

            //define nullable type variable, which value is define null

            int? number = null;

            // is the hasvalue property which return true or false

            try

            {

                Console.WriteLine(number.Value);  //for true

            }

            catch(System.InvalidOperationException e)

            {

                Console.WriteLine(e.Message);

            }        
  

            // if we have provide default value to null able type variable through GetValueOrDefault() function          

               number = number.GetValueOrDefault();              

            //then

            try

             {

                   Console.WriteLine("\nGet Default Value: {0}", number.Value);  //for true

             }

             catch(System.InvalidOperationException e)

             {

                 Console.WriteLine(e.Message);

             }

               // if we have provide a value to nullable type variable through user

               number = 10;

               //then           

             try

             {

                   Console.WriteLine("\nGet User Value   : {0}", number.Value);  //for true

             }

             catch(System.InvalidOperationException e)

             {

                 Console.WriteLine(e.Message);

             }

               Console.ReadLine();

         }

    }

}

Output