[Dev-C++] Problems with pointers to member functions

[Tulius L. <tul...@ho...>]

Hi Folks,


      I've been trying to work with pointers to member functions (after I 
saw the code posted by Japp de Wolff) to implement a finite-state machine 
for a SDL sprite engine.

      After a few bumps I managed to compile the code. But it crashes when 
it runs (when it hits the member function).

      Can anyone tell me please what's wrong with my code?


      TIA
      Tulius Lima

------------

typedef void (Sprite::*Action)();

class Sprite
{
public:

  // operations
  void moveUp();
  void moveDown();
  void moveLeft();
  void moveRight();
  void stop();
  void move();

};


int main(int argc, char *argv[])
{
  Sprite ship;
  Action action;
  Uint8* keys;

  // SDL code omitted

  int done = 0;
  while (!done)
  {
    keys = SDL_GetKeyState(NULL);
    if ( keys[SDLK_UP] )
    {
      action = &Sprite::moveUp;
    }
    if ( keys[SDLK_DOWN] )
    {
      action = &Sprite::moveDown;
    }
    if ( keys[SDLK_LEFT] )
    {
      action = &Sprite::moveLeft;
    }
    if ( keys[SDLK_RIGHT] )
    {
      action = &Sprite::moveRight;
    }

    (ship.*action)(); // <--- problematic code

    SDL_Flip(screen);
  }

  // SDL finalization code omitted

  return 0;
}
-------------------- end

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