postfix.cpp

来自「本课程主要介绍面向对象程序设计的方法和c++语言的基本概念。以c++语言中的面向」· C++ 代码 · 共 48 行

// postfix.cpp
// overloaded ++ operator in both prefix and postfix
#include <iostream>
using namespace std;
////////////////////////////////////////////////////////////////
class Counter
   {
   private:
      unsigned int count;         //count
   public:
      Counter() : count(0)        //constructor  no args
         {  }
      Counter(int c) : count(c)   //constructor, one arg
         {  }
      unsigned int get_count() const //return count
         { return count; }

      Counter operator ++ ()      //increment count (prefix)
         {                        //increment count, then return
         return Counter(++count); //an unnamed temporary object
         }                        //initialized to this count

      Counter operator ++ (int)   //increment count (postfix)
         {                        //return an unnamed temporary
         return Counter(count++); //object initialized to this
         }                        //count, then increment count
   };
////////////////////////////////////////////////////////////////
int main()
   {
   Counter c1, c2;                       //c1=0, c2=0

   cout << "\nc1=" << c1.get_count();    //display
   cout << "\nc2=" << c2.get_count();

   ++c1;                                 //c1=1
   c2 = ++c1;                            //c1=2, c2=2 (prefix)

   cout << "\nc1=" << c1.get_count();    //display
   cout << "\nc2=" << c2.get_count();

   c2 = c1++;                            //c1=3, c2=2 (postfix)

   cout << "\nc1=" << c1.get_count();    //display again
   cout << "\nc2=" << c2.get_count() << endl;
   return 0;
   }