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

These files are located in /usr/include/ and subdirectories (at least on my debian laptop). Looking at /usr/include/stdio.h

shows a typical guard,

#ifndef _STDIO_H
# define _STDIO_H       1

And checking for cpp, grep __cplusplus,

#if !defined __cplusplus || defined __STDC_LIMIT_MACROS

...