Question

What is printed by the following C program?

int f(int x, int *py, int **ppz) {
  int y, z;
  **ppz += 1; z = **ppz;
  *py += 2; y = *py;
  x += 3;
  return x+y+z;
}
void main() {
  int c, *b, **a;
  c = 4; b = &c; a = &b;
  printf("%d", f(c,b,a));
}

Accepted Answer

The correct answer is (B) 19. f is called with x=4 (copy of c, pass-by-value), py=b (points to c), ppz=a (points to b). **ppz += 1: c becomes 4+1=5. z = **ppz = 5. *py += 2: c becomes 5+2=7. y = *py = 7. x += 3: x becomes 4+3=7 (local copy only, doesn't affect c). Return x+y+z = 7+7+5 = 19.

Explanation