c# ?? Operator

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Every once in a while, you run into something that makes you go “damn, I wish I knew that before.” In this case, I was given a lesson by the wonderful Resharper.

I had a variable that I wanted to have a default value if it was null. So, I figured something like this would work:

x = (x==null) ? "1" : x;

If x is null, it will be given a default value of 1.

Resharper corrected me to this:

x = x ?? "1";

“What the heck is that operator?” said past me. Answer:

“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.”

In other words, if the left side of ?? is null, the right side is returned.


My name is Andrew McGivery. I currently work full time as an application developer at Manulife Financial in Canada. My current passion is building and leading highly engaged teams where employee happiness, learning, and growth is a priority.

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