Introduction

Null coalescing operator(??) is one of the really great feature of C# language . This operator (??) is used to check whether object is null or not . If the object is null it provides a default value. Most of the programmer didn't use this coalescing operator in frequent programming practices.

We can say that coalescing operator (??) is used to define a default value for nullable value types or reference types. When a nullable type is assigned to a non-nullable type the ?? operator defines the default value to be returned. If a programmer try to assign a nullable value type to a non-nullable value type and he/she not using the ?? operator then a compile time error will be generated .

Example:

using System;

namespace coalescingOperatorDemo
{
class Program
{

static void Main()
 {

Console.WriteLine(N);

N = 1;

Console.WriteLine(N);

Console.ReadKey();

}

public static int? _num;

public static int? N

{

get
 {
 return _num ?? 0;
 }

set
 {
 _num = value;

}

}

}

}