Program:

The source code to demonstrate the Nullable data types is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

//Program to demonstrate the Nullable data types in C#

using System;

class NullableDemo
{
    static void Main(string[] args)
    {
        int? intVal1 = null;
        int? intVal2 = 786;

        float?  floatVal1 =  3.14F;
        float? floatVal2 = new float?();

        bool?   boolval = new bool?();
        
        Console.WriteLine("Nullable Integers : {0}, {1}",intVal1,intVal2);
        Console.WriteLine("Nullable Floats   : {0}, {1}", floatVal1, floatVal2);
        Console.WriteLine("Nullable boolean  : {0}", boolval);
    }
}

Output:

Nullable Integers : , 786
Nullable Floats   : 3.14,
Nullable boolean  :
Press any key to continue . . .

Explanation:

In the above program, we created a class NullableDemo that contains the Main() method. In the Main() method we created nullable variables using a question mark. Variable declared as a nullable type that can store normal values as well as null values, here we will question mark to declare a variable as a nullable. 

Then printed the values of all variables on the console screen.