What is __declspec and when do I need to use it?

Question

I have seen instances of __declspec in the code that I am reading. What is it? And when would I need to use this construct?

Answer 1

Another example to illustrate the __declspec keyword:

When you are writing a Windows Kernel Driver, sometimes you want to write your own prolog/epilog code sequences using inline assembler code, so you could declare your function with the naked attribute.

__declspec( naked ) int func( formal_parameters ) {}

Or

#define Naked __declspec( naked )
Naked int func( formal_parameters ) {}

Please refer to naked (C++)