++和自减--都是一元运算符，它的前置形式和后置形式都可以被重载。请看下面的例子：
#include <iostream> #include <iomanip> using namespace std; //秒表类 class stopwatch{ public: stopwatch(): m_min(0), m_sec(0){ } public: void setzero(){ m_min = 0; m_sec = 0; } stopwatch run(); // 运行 stopwatch operator++(); //++i，前置形式 stopwatch operator++(int); //i++，后置形式 friend ostream & operator<<( ostream &, const stopwatch &); private: int m_min; //分钟 int m_sec; //秒钟 }; stopwatch stopwatch::run(){ ++m_sec; if(m_sec == 60){ m_min++; m_sec = 0; } return *this; } stopwatch stopwatch::operator++(){ return run(); } stopwatch stopwatch::operator++(int n){ stopwatch s = *this; run(); return s; } ostream &operator<<( ostream & out, const stopwatch & s){ out<<setfill('0')<<setw(2)<<s.m_min<<":"<<setw(2)<<s.m_sec; return out; } int main(){ stopwatch s1, s2; s1 = s2++; cout << "s1: "<< s1 <<endl; cout << "s2: "<< s2 <<endl; s1.setzero(); s2.setzero(); s1 = ++s2; cout << "s1: "<< s1 <<endl; cout << "s2: "<< s2 <<endl; return 0; }运行结果：
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