Question

I have this simple code

#include <stdio.h>    
#include <OpenGL/glext.h>    
#include <OpenGL/gl.h>    

int main (int argc, const char * argv[])
{
    printf("Hello, World!\n");
    return 0;
}

If I comment out the line with “glext.h” it compiles and runs fine in xcode 4 if I uncomment that line I get 345 errors most of them ‘expected * before *’ …
What is going on?! both gl.h and glext.h are inside the OpenGL framework but no matter if I incluhe it or not I get the same error. I tried GCC 4.2 as well as LLVM GCC 4.2 and LLVM (in this case 21 semantic and parse errors).

I am sure my lack of experience with C is causing this but I am surprised gl.h has no problem but glext.h has.

Even if I try to compile in from the command line by gcc I get lots of

/System/Library/Frameworks/OpenGL.framework/Headers/glext.h:3137: error: expected ‘)’ before ‘const’

Any ideas?

Answer 1

It’s a bug with glext.h. If you look at that file, you’ll see that it has a bunch of definitions that use GLenum, but GLenum isn’t defined anywhere in that file. So, before you include glext.h, you need to include a file that defines GLenum. The easiest thing to do is to include gl.h first instead of second:

#include <stdio.h>
#include <OpenGL/gl.h>
#include <OpenGL/glext.h>