#include <iostream> using namespace std;

class A { private: double* m_i; public: A(double i) { m_i = new double; *m_i = i; }

A(A& x) { m_i = x.m_i; cout<<*m_i<<endl; }

~A() { cout<<"m_i is: "<<*m_i<<endl; *m_i = -1; delete m_i; m_i = NULL; }

void print() { cout<<"the value is: "<<*m_i<<endl; } };

A f(A a) { return a; a.print(); }

void main() { A a(23); f(a); }

~A()
 {
  cout&lt;&lt;"m_i is: "&lt;&lt;*m_i&lt;&lt;endl;
  *m_i = -1;
  m_i = NULL;
  delete m_i;                                         // 这里需要交换顺序   原程序中是先delete再赋值所以出现错误
 }

A f(A a)
{
 a.print();
 return a;                                        //这里虽没有错误   不过我想程序员本意应该是这样
}