Question

Is there a way to pass null arguments to C# methods (something like null arguments in c++)?

For example:

Is it possible to translate the following c++ function to C# method:

private void Example(int* arg1, int* arg2) {     if(arg1 == null)     {         //do something     }     if(arg2 == null)     {         //do something else     } } 

Answer 1

Yes. There are two kinds of types in .NET: reference types and value types.

References types (generally classes) are always referred to by references, so they support null without any extra work. This means that if a variable’s type is a reference type, the variable is automatically a reference.

Value types (e.g. int) by default do not have a concept of null. However, there is a wrapper for them called Nullable. This enables you to encapsulate the non-nullable value type and include null information.

The usage is slightly different, though.

// Both of these types mean the same thing, the ? is just C# shorthand. private void Example(int? arg1, Nullable<int> arg2) {     if (arg1.HasValue)         DoSomething();      arg1 = null; // Valid.     arg1 = 123;  // Also valid.      DoSomethingWithInt(arg1); // NOT valid!     DoSomethingWithInt(arg1.Value); // Valid. }