C++ Include Guards for Standard Headers

Question

I am wondering if/ what include guards on files like windows.h, math.h, iostream, stdio... etc.

Since I have thos

Answer 1

Many compilers support #pragma once. All of the standard libraries already have guards either in the form of #pragma once or appropriate preprocessor macros. You can learn more about what the guards look like on the Wikipedia page. The fastest way to be sure is to right click on the include file definition and ask the development environment (Visual Studio/Eclipse) to open the file. Then you will see the guards.