This is my very first question here. I bumped into a method like this in C#:
void Do(string action!) { ... }
And don't get what the ! after action is and it does. Can you help me understand it?
C# what is the exclamation point positioned after the parameter name
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2 Answers
This is named the bang operator, !, which can be positioned after any identifier in a parameter list and this will cause the C# compiler to emit standard null checking code for that parameter. For example:
void Do(string action!) { ... }
Will be translated into:
void Do(string action!) {
if (action is null) {
throw new ArgumentNullException(nameof(action));
}
...
}
btw, at the moment, this feature is not available yet. You can find more info here.
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-forgiving
you use the null-forgiving operator to declare that expression x of a reference type isn't null
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