921123-2.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

typedef struct
{
  unsigned short b0, b1, b2, b3;
} four_quarters;

four_quarters x;
int a, b;

void f (four_quarters j)
{
  b = j.b2;
  a = j.b3;
}

main ()
{
  four_quarters x;
  x.b0 = x.b1 = x.b2 = 0;
  x.b3 = 38;
  f(x);
  if (a != 38)
    abort();
  exit (0);
}