What is the usage of #if DEBUG pre-processor directive in C#? When must we use this?

Question

What is the usage of #if DEBUG pre-processor directive in C#? When must we use this?

Answer 1

You might feel more comfortable with the Conditional attribute, which can be used to exclude entire methods, without needing to complicate the source with conditionals on the calling side:

[Conditional("DEBUG")]
void Foo()
{
}

Foo() can be safely called in both debug and release - however in release mode, it would be a no-op.