1  typedef struct {
       2    int a, b, c, d, e, f;
       3  } A;
       4  
       5  void foo (A *v, int w, int x, int *y, int *z)
       6  {
       7  }
       8  
       9  void
      10  bar (A *v, int x, int y, int w, int h)
      11  {
      12    if (v->a != x || v->b != y) {
      13      int oldw = w;
      14      int oldh = h;
      15      int e = v->e;
      16      int f = v->f;
      17      int dx, dy;
      18      foo(v, 0, 0, &w, &h);
      19      dx = (oldw - w) * (double) e/2.0;
      20      dy = (oldh - h) * (double) f/2.0;
      21      x += dx;
      22      y += dy;
      23      v->a = x;
      24      v->b = y;
      25      v->c = w;
      26      v->d = h;
      27    }
      28  }
      29  
      30  int main ()
      31  {
      32    A w = { 100, 110, 20, 30, -1, -1 };
      33    bar (&w,400,420,50,70);
      34    if (w.d != 70)
      35      abort();
      36    exit(0);
      37  }