Thread: box-and-circle diagram

hi, i am to draw a box-and-circle diagram to show bindings of variables after each of the two assignments to **x. and note alias situations. can someone help me out or point to a page with a clear explanation.

Code:

main() {
int **x;
int *y;
int z;
x = &y;
y = &z;
z = 1;
*y = 2;
*x = y;
**x = z;
printf("%d\n", *y);
z = 3;
printf("%d\n", *y);
**x = 4;
printf("%d\n", z);
}