ch18_5.cpp

上面的程序是关于钱能的C++课后习题答案

//**********************
//**    ch18_5.cpp    **
//**********************

#include <iostream.h>

class Increase{
public:
  Increase(int x):value(x){}
  friend Increase & operator++(Increase & );     //前增量
  friend Increase operator++(Increase &,int);    //后增量
  void display(){ cout <<"the value is " <<value <<endl; }
private:
  int value;
};

Increase & operator++(Increase & a)
{
  a.value++;                           //前增量
  return a;                            //再返回原对象
}

Increase operator++(Increase& a, int)
{
  Increase temp(a);                //通过拷贝构造函数保存原有对象值
  a.value++;                       //原有对象增量修改
  return temp;                     //返回原有对象值
}

void main()
{
  Increase n(20);
  n.display();
  (n++).display();                 //显示临时对象值
  n.display();                     //显示原有对象
  ++n;
  n.display();
  ++(++n);
  n.display();

  (n++)++;                         //第二次增量操作对临时对象进行
  n.display();
  cin.get();
}