指针的新手，有一个相当新颖的问题

Question

#include <iostream>
using namespace std;

int main ()
{
  int firstvalue = 5, secondvalue = 15;
  int * p1, * p2;

  p1 = &firstvalue;  // p1 = address of firstvalue
  p2 = &secondvalue; // p2 = address of secondvalue

  *p1 = 10;          // value pointed to by p1 = 10
  *p2 = *p1;
           // value pointed to by p2 = value pointed to by p1
  p1 = p2;           // p1 = p2 (value of pointer is copied)
  *p1 = 20;          // value pointed to by p1 = 20

  cout << "firstvalue is " << firstvalue << '\n';
  cout << "secondvalue is " << secondvalue<< '\n';
  return 0;
}

结果如何可能是：firstvalue是10secondvalue是20

它不是第一个值为20，第二个为10，因为编译器从头到尾都读取吗？

Answer 1

在这些语句中

Answer 2

[*p1 = 10表示p1指向的变量是10，所以firstvalue = 10。