DEV Community

Matheus Gomes πŸ‘¨β€πŸ’»
Matheus Gomes πŸ‘¨β€πŸ’»

Posted on

Coalescing operator and Compound assignment operator in C#

Hello! Today i want to ask you this: Have you ever used a Null Coalescing operator or even a Compound assignment operator in C# ?

I never.

Until today i had never heard about this things, so i want to share with you what i learned about and how it can be applied to your code.

The problem

Let's say you want to give a given variable the value of null.

namespace Course {
    class Program {
        static void Main(string[] args) {

            double? x = null;
            double? y = 10.0;

            Console.WriteLine(x.Value);
        }
    }
}
Enter fullscreen mode Exit fullscreen mode

Now, if we want to print the value on the screen it will accuse the following error:

"Unhandled Exception: System.InvalidOperationException: Nullable object must have a value."
Enter fullscreen mode Exit fullscreen mode

Let's see how to get around this...

The old way πŸ‘Ž

The old and 'commom way' to check this is using if else operators like this:

namespace Course {
    class Program {
        static void Main(string[] args) {

            double? x = null;
            double? y = 10.0;

            // check if x is null
            if (x.HasValue)
                Console.WriteLine(x.Value);
            else
                Console.WriteLine("X is null");

            // check if y is null
            if (y.HasValue)
                Console.WriteLine(y.Value)
            else
                Console.WriteLine("Y is null");
        }
    }
}
Enter fullscreen mode Exit fullscreen mode

We see that in this case we cannot place a default value to x and y operators. So we display on screen when it is null.

The Null Coalescing operator way πŸ‘Œ

First, a null coalescing operator (??) is used to define a default value for nullable value types or reference types. It returns the left-hand operand if the operand is not null, otherwise, it returns the right operand.

So it's mainly used to simplify checking for null values and also assign a default value to a variable when the value is null.

Using our example:

namespace Course {
    class Program {
        static void Main(string[] args) {
            double? x = null;
            double? y = 10.0;

            double x = x ?? 0.0;
            Console.WriteLine(x.Value);
            double y = y ?? 0.0;
            Console.WriteLine(y.Value);
        }
    }
}
Enter fullscreen mode Exit fullscreen mode

This way i can make a default value on x and y when one of them is null. And so, we can print on screen!

But can it be better?

The Compound assignment operator way 😎

The Compound assignment operator (??=) was introduced on C# 8.0 and has made our job easier. It simply reduces what we have to write and has the same result.

Instead of writing double x = x ?? 0.0;
We can just write double x ??= 0.0;

namespace Course {
    class Program {
        static void Main(string[] args) {
            double? x = null;
            double? y = 10.0;

            double x ??= 0.0;
            double y ??= 0.0;
        }
    }
}
Enter fullscreen mode Exit fullscreen mode

Simple, right?

Hope you enjoyed this post, it's simple but it's something worth sharing for me.

Thanks for your time!😊

Links:
https://dzone.com/articles/nullable-types-and-null-coalescing-operator-in-c

https://dev.to/mpetrinidev/the-null-coalescing-operator-in-c-8-0-4ib4

https://docs.microsoft.com/pt-br/dotnet/csharp/language-reference/operators/null-coalescing-operator

Top comments (3)

Collapse
 
wakeupmh profile image
Marcos Henrique

🀘

Collapse
 
saint4eva profile image
saint4eva

Good article. Thank you.

Collapse
 
arthurbarbero profile image
Arthur Barbero

Awesome Dude, simple but unknown by most programmers