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How to use null-coalescing operator?

Tarun Kumar 2124 04-Jul-2017

How to use ?? null-coalescing operator in c# . I have never used ?? operator. And  How we can assign default value when it is null using ?? Operator.

Please help 
c# c# 
Updated on 19-Jun-2019
Tarun Kumar

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2 Answers

Shadman Kudchikar

Shadman Kudchikar

19-Jun-2019

The ?? operator is called the null-coalescing operator. You can use it to provide a default value for nullable value types or for reference types. The operator returns the left value if it’s not null; otherwise, the right operand. Here is an example of using the operator. 

int? x = null;
int y = x ?? -1;

In this case, the value of y is -1 because x is null. You can also nest the null-coalescing operator, below is an example, 

int? x = null;
int? z = null;
int y = x ??
        z ??
        -1;

Of course, you can achieve the same with an if statement but the null-coalescing operator can shorten your code and improve its readability.

You can learn more about Null Coalescing Operator C# here.

Sushant Mishra

Sushant Mishra

06-Jul-2017

The ?? operator is called the null-coalescing operator. It returns the left-hand operand if the operand is not null; otherwise, it returns the right hand operand.

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication1
{
    class Program
    {
        static int? GetNullableInt()
        {
            return null;
        }
 
        static string GetStringValue()
        {
            return "Mindstick Softwares";
        }
 
        static void Main()
        {
 
                        int? x = null;
 
            // Set y to the value of x if x is NOT null; otherwise,
            // if x = null, set y to 5.
            int y = x ?? 5;
 
            // Assign i to return value of the method if the method's result
            // is NOT null; otherwise, if the result is null, set i to the
            // default value of int.
            int i = GetNullableInt() ?? default(int);
 
            string m = GetStringValue();
            // Display the value of s if s is NOT null; otherwise, 
            // display the string "Unspecified".
           
Console.WriteLine(m?? "Unspecified");
            Console.WriteLine(i);
            Console.ReadKey();
        }
    }
}
 
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