nullableexample.cs

// See https://aka.ms/new-console-template for more information

int ?nullable = null;

//var a = (int)(nullable + nullable); NUllable object must have a value

nullable = 44;

var a = (int)(nullable + nullable); //Work fine but it's error prone.

Console.WriteLine(a);

int value=nullable.GetValueOrDefault(-1);

if (value < 0)
{
    Console.WriteLine("Maalesef İstenen Değer Bulunmamakta.");
}
else {
    var b = value + value;
    Console.WriteLine(b);
        }

if (nullable.HasValue)
{
    Console.WriteLine("Value Var");
}
else
{
    Console.WriteLine("Value Yok.");
}

int ?nullable2=null;
if (nullable2.HasValue)
{

}
else
{
    Console.WriteLine("Nullable 2'de value yok  arkadaşım.");
}
//Work Just fine.

Nullable<int> myNullableInt = 88; //This thinks is same as int?

//Nullable value types is just works.