MinGW and "declaration does not declare anything"
I'm working on converting a Linux project of mine to compile on Windows using MinGW. It compiles and runs just fine on Linux, but when I attempt to compile it with MinGW it bombs out with the following error message:
camera.h:11: error: declaration does not declare anything
camera.h:12: error: declaration does not declare anything
I'm kind of baffled why this is happening, because
- I'm using the same version of g++ (4.4) on both Linux and Windows (via MinGW).
- The contents of camera.h is absurdly simple.
Here's the code. It's choking on lines 11 and 12 where float near; and float far; are defined.
#include "Vector.h"
#ifndef _CAMERA_H_
#define _CAMERA_H_
class Camera{
public:
Vector eye;
Vector lookAt;
float fov;
float near;
float far;
};
#endif
Thanks for your help.
EDIT: Thanks both Dirk and mingos, that was exactly the 开发者_如何学Goproblem!
Edit If you happen to include windef.h (either directly or indirectly), you will find
#define FAR
#define far
#define NEAR
#define near
there. I think, that this is the culprit.
Try
#undef near
#undef far
before your class definition.
Try giving them different names, like
float my_near;
float my_far;
I recall Borland using "near" and "far" as keywords (my 1992 Turbo C had these, back in MS-DOS era). Dunno if this is the case with gcc, but you can always try that.
In <windef.h>, you'll find on the following lines:
#define NEAR
#define near
Simple answer: you can't #undef them because they're a part of the Windows headers (_WINDEF_H will still be defined even if you #undef those definitions, so it won't be re-included if you try to #include <windef.h> again, not to mention the fact that if you #undef _WINDEF_H before using #include <windef.h> after your class definition, you'll end up with duplicate definitions for things like RECT, LONG, PROC and more), so the only other solution is to change your variable names.
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