堆栈地址和堆地址之间的关系？

Question

基本上，我们被要求预测以下程序的输出。我有些困惑，我已经在代码本身的注释中指出了这一点：

#include <stdio.h>
#include <stdlib.h>

void foo ( int * z) ;

int main () {

  int x = 10;
  int * y = (int*) malloc(sizeof(int));
  *y = x;
  printf("x = %d	*y = %d
", x, *y); //This should print x = 10, *y = 10

  if (&x > y ) { //I am confused about this particular scenario, as far as I know we are not able to guarantee when the heap addresses are higher or lower than stack addresses, I believe this differs from system to system?
    printf ("XXX
"); //So there is no way of knowing which if statement we go to right?
  }
  else {
    printf ("YYY
");
  }
  foo(&x);
  foo(y);

  if (y!=0) free(y);
  return 0;
}

void foo ( int * z) {
  int w = 5;
  if (&w > z ) { //Again when we come here is there any way for us to know exactly which if statement we will go into? Considering that we don't really know how the system will allocate memory?
    printf ("WWW
");
  }
  else {
    printf ("ZZZ
");
  }
}

任何帮助将不胜感激！谢谢！