The file systems on Windows are case insensitve so either one will work when compiling on Windows. However, if you were to compile on Linux using the MinGW cross compiler for example, the case would matter.
windows.h header always seems to be lower case.
Windows.h file provided with Microsoft's tools have used a variety of cases.
- old VC++ installations (VC++98 and earlier) appear to install
WINDOWS.H- all caps
- newer VC++ installations and Windows SDKs seem to use
- some mobile device SDKs (PocketPC or Windows mobile) use
windows.h- all lowercase.
windows.h will always work on both Windows and a Linux cross compile, I'd use
#include <windows.h> if I ever thought about it. Which I can't recall doing until answering this.
I wouldn't worry about this too much. Even if the capitalized form finds its way onto a Linux MinGW build, an easy (if maybe annoying) fix is to create a
Windows.h file that just turns around and includes