SDL_PLATFORM_WINDOWS3
A preprocessor macro that is only defined if compiling for windows.
Usage
#include "SDL3/SDL.h"
#define SDL_PLATFORM_WINDOWS 1
Header file
Defined in SDL3/SDL_platform_defines.h
Overview
This also covers several other platforms, like Microsoft GDK, Xbox, WinRT, etc. Each will have their own more-specific platform macros, too.