C++_运算符重载_前缀自增与后缀自增

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由于前缀自增与后缀自增在如果通过运算符重载在形式上相同，都为

以Date类为例 Date& operator++(Date &)（全局函数）/ Date& operator++( )（成员函数）无法区分。

故人为规定前缀自增与后缀自增运算符的表达形式：

由于编译器必须能够识别出前缀自增与后缀自增，故人为规定了用一个 int 区分，并没有实际的含义。

前缀自增示例

Calendar& Calendar::operator++(){tick();return *this;}

后缀自增示例

Calendar Calendar::operator++(int){Calendar temp = *this;tick();return temp;/*tick();return *this;*/}

上面会出现3次析构，Temp会导致一次析构。

下面只有两次析构，并没有保存传进来的副本

头文件

#ifndef CALENDAR#define CALENDAR#include <iostream>#include <cstdio>#include <iomanip>#include <windows.h>using namespace std;class Calendar;ostream &operator<<(ostream & output, Calendar &C);class Calendar{friend ostream &operator<<(ostream & output, Calendar &C);public:Calendar(int y = 2015, int m = 8, int d = 6, int h = 17, int mm = 9, int s = 0):year(y), month(m), day(d), hour(h), minute(mm), second(s){}//operator Calendar &operator++();Calendar operator++(int);void tick(){++second;}~Calendar(){cout << "Destructor" << endl;}private:int day;int month;int year;int hour;int minute;int second;FILE *fp;};Calendar& Calendar::operator++(){tick();return *this;}Calendar Calendar::operator++(int){Calendar temp = *this;tick();return temp;/*tick();return *this;*/}ostream &operator<<(ostream & output, Calendar &C){output << ""<< setw(15) << "Year: " << C.year << " "<< setw(15) << "Month: " << C.month << " "<< setw(15) << "Day: " << C.day << " " << endl<< setw(15) << "Hour: " << C.hour << " "<< setw(15) << "Minute: " << C.minute << " "<< setw(15) << "Second: " << C.second << " " << endl;return output;}#endif

主函数

int main(){Calendar a;cout << a << endl;cout << ++a << endl;cout << a++ << endl;cout << a << endl;return 0;}

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