C# NULLABLES

C# provides a special data types, the nullable types, to which you can assign normal range of values as well as null values.

For example, you can store any value from -2,147,483,648 to 2,147,483,647 or null in a Nullable\<Int32> variable.

using System;

namespace ConsoleApp1
{
    class NullablesAtShow
    {
        static void Main(string[] args)
        {
            int? num1 = null;
            int? num2 = 45;
            double? num3 = new double?();
            double? num4 = 3.14157;

            bool? boolval = new bool?();
            // display the values

            Console.WriteLine("Nullables at Show: {0}, {1}, {2}, {3}",num1, num2, num3, num4);
            Console.WriteLine("A Nullable boolean value: {0}", boolval);
            Console.ReadLine();

            //Nullables at Show: , 45, , 3.14157
            //A Nullable boolean value:
        }
    }
}

The Null Coalescing Operator (??)

The null coalescing operator is used with the nullable value types and reference types. It is used for converting an operand to the type of another nullable (or not) value type operand, where an implicit conversion is possible

using System;

namespace ConsoleApp1
{
    class NullablesAtShow
    {
        static void Main(string[] args)
        {

            double? num1 = null;
            double? num2 = 3.14157;
            double num3;
            num3 = num1 ?? 5.34;
            Console.WriteLine(" Value of num3: {0}", num3);
            num3 = num2 ?? 5.34;
            Console.WriteLine(" Value of num3: {0}", num3);
            Console.ReadLine();
            //Value of num3: 5.34
            //Value of num3: 3.14157
        }
    }
}