GLFW setting callback functions - c++

Question

What data type to use when setting a callback functions in GLFW?
I try setting a function to type void but gives me a compile error. Changing it to void __stdcall gives me an RT error, but how do I use the typedef's of GLFW such as GLFW*fun? I think this is the right one to do. I really need an example source code.
btw, I define GLFW as GLFW_DLL
UPDATE
My code's look like this:
(I did it in three ways)
1
prototype. because these* are below main
this one gives me a compile error(invalid conversion)
void MouseClick(int, int);
void Keyboard(int, int);
//...
2
//appending `__stdcall` get compiled but gives me `RT error`
void __stdcall MouseClick(int, int);
void __stdcall Keyboard(int, int);
3
on my other project, I use GLFW_BUILD_DLL and compiles in MSVS with casting.
glfwSetKeyCallback((GLFWkeyfun)Keyboard);
but now, I can't do it in MinGW with the GLFW_DLL
void MouseClick(int x, int y) {
}
in main...
int main() {
//glfw intialization...
glfwSetKeyCallback(Keyboard);
//other setters
}
but, how do I do it this way?
GLFWmouseposfun MousePos {
}
//...

Answer 1

According to the documentation for GLFW v2.x the prototype for what you pass to glfwSetKeyCallback (etc.) is
void GLFWCALL functionname( int key, int action );
Here is a complete C program which will print out the key events:
#include <stdio.h>
#include <GL/glfw.h>
void GLFWCALL keyfun(int key, int action) {
printf("%d %d\n", key, action);
}
int main() {
glfwInit();
glfwOpenWindow(640, 480, 0, 0, 0, 0, 0, 0, GLFW_WINDOW);
glfwSetKeyCallback(keyfun);
while(1) {
glfwSwapBuffers();
}
}
If this code doesn't work you are likely linking to GLFW incorrectly.

Answer 2

Ahm, sorry my fault. I just didn't noticed that I have this Vec2f To_OGL_Coords(int x, int y) inside void MousePos(int x, int y) which I haven't included in my post.
As I said, it is Vec2f which I left out the 3rd(z) coordinate to NULL that causes the runtime error. Method number 2 should work here, same as Jacob Parker's answer. I just really don't know much the effects of those pointers if not used correctly.
(PS. I am working on 2D that's why I neglected the z-coordinate. My bad)