Absolute link works but relative link don’t in #include

  absolute, c++, include, sdl

I was making a C++ project using atom and MinGW. The project required libraries that are not present by default. So I just downloaded and copy-pasted them in C:/MinGW/include/ . Using them directly in #include statement as #include<SDL2/SDL.h> didn’t work but using absolute link as #include<C:/MinGW/include/SDL2/SDL.h> worked. What could be the reason?

Source: Windows Questions C++