C++各个运算符重载实例

// OperatorRewrite1.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include <iostream>

using namespace std;


enum style_enum{ zero, one, two, three };

class CFraction
{
private:
	int nume;  // 分子  
	int deno;  // 分母  
public:
	CFraction(int nu = 0, int de = 1) :nume(nu), deno(de){}   //构造函数，初始化用  

	void simplify();                //化简（使分子分母没有公因子）  

	//输入输出重载  
	friend ostream& operator<<(ostream &out, const CFraction &cf);//必须是友元函数，相当于独立函数
	friend istream& operator>>(istream &in, CFraction &cf);

	//加减乘除，结果需要化简  
	friend CFraction operator+(const CFraction &lcf, const CFraction &rcf);
	friend CFraction operator-(const CFraction &lcf, const CFraction &rcf);
	friend CFraction operator*(const CFraction &lcf, const CFraction &rcf);
	friend CFraction operator/(const CFraction &lcf, const CFraction &rcf);

	//关系运算符  
	friend bool operator>(const CFraction &lcf, const CFraction &rcf);//left right
	friend bool operator<(const CFraction &lcf, const CFraction &rcf);
	friend bool operator>=(const CFraction &lcf, const CFraction &rcf);
	friend bool operator<=(const CFraction &lcf, const CFraction &rcf);
	friend bool operator==(const CFraction &lcf, const CFraction &rcf);
	friend bool operator!=(const CFraction &lcf, const CFraction &rcf);


	//取+、-一目运算符  
	CFraction operator+();
	CFraction operator-();

};



void CFraction::simplify()
{
	int v1 = nume;
	int v2 = deno;
	while (v2)//采用
	{
		int temp = v2;
		v2 = v1 % v2;
		v1 = temp;
	}
	nume /= v1;
	deno /= v1;
	if (deno < 0)
	{
		deno = -deno;
		nume = -nume;
	}
}

//输出重载  
ostream& operator<<(ostream &out, const CFraction &cf)
{
	out << cf.nume << '/' << cf.deno;
	return out;
}

//输入重载  
istream& operator>>(istream &in, CFraction &cf)
{
	char ch;
	while (1)
	{
		in >> cf.nume >> ch >> cf.deno;
		if (cf.deno == 0)
			cerr << "分母为0请重新输入\n";
		else if (ch != '/')
			cerr << "格式错误（形如m/n）请重新输入\n";
		else break;
	}
	return in;
}
//加法重载  
CFraction operator+(const CFraction &lcf, const CFraction &rcf)
{
	CFraction cf;
	cf.nume = lcf.nume*rcf.deno + lcf.deno*rcf.nume;
	cf.deno = lcf.deno*rcf.deno;
	cf.simplify();
	return cf;
}
//减法重载  
CFraction operator-(const CFraction &lcf, const CFraction &rcf)
{
	CFraction cf;
	cf.nume = lcf.nume*rcf.deno - rcf.nume*lcf.deno;
	cf.deno = lcf.deno*rcf.deno;
	cf.simplify();
	return cf;
}
//乘法重载  
CFraction operator*(const CFraction &lcf, const CFraction &rcf)
{
	CFraction cf;
	cf.nume = lcf.nume*rcf.nume;
	cf.deno = lcf.deno*rcf.deno;
	cf.simplify();
	return cf;
}
//除法重载  
CFraction operator/(const CFraction &lcf, const CFraction &rcf)
{
	CFraction cf;
	cf.nume = lcf.nume*rcf.deno;
	cf.deno = lcf.deno*rcf.nume;
	cf.simplify();
	return cf;
}
//取正重载  
CFraction CFraction::operator+()
{
	simplify();
	if (nume < 0)
		nume = -nume;
	return *this;
}
//取负重载  
CFraction CFraction::operator-()
{
	simplify();
	nume = -nume;
	return *this;
}


//大于号重载  
bool operator>(const CFraction &lcf, const CFraction &rcf)
{
	int l_nume = lcf.nume * rcf.deno;//通分后相减
	int r_nume = rcf.nume * lcf.deno;
	int common_deno = lcf.deno * rcf.deno;
	if ((l_nume - r_nume) * common_deno > 0) return true;
	return false;
}

//小于号重载  
bool operator<(const CFraction &lcf, const CFraction &rcf)
{
	return !(lcf > rcf);
}

//等于重载  
bool operator==(const CFraction &lcf, const CFraction &rcf)
{
	return lcf.nume == rcf.nume && lcf.deno == rcf.deno;
}

//不等于重载  
bool operator!=(const CFraction &lcf, const CFraction &rcf)
{
	return !(lcf == rcf);
}

//  
bool operator>=(const CFraction &lcf, const CFraction &rcf)
{
	if (lcf < rcf) return false;
	return true;
}

//  
bool operator<=(const CFraction &lcf, const CFraction &rcf)
{
	if (lcf > rcf) return false;
	return true;
}

int main()
{
	CFraction cf1;
	CFraction cf2;
	cin >> cf1 >> cf2;
	cout << "cf1: " << cf1 << '\t' << "cf2: " << cf2 << endl
		<< "cf1 + cf2 : " << cf1 + cf2 << endl
		<< "cf1 - cf2 : " << cf1 - cf2 << endl
		<< "cf1 * cf2 : " << cf1*cf2 << endl
		<< "cf1 / cf2 : " << cf1 / cf2 << endl
		<< " +cf1 :     " << +cf1 << endl
		<< " -cf1 :     " << -cf1 << endl
		<< " +cf2 : 　　" << +cf2 << endl
		<< " -cf2 :     " << -cf2 << endl
		<< " cf1 > cf2? 1/YES 0/NO " << (cf1 > cf2) << endl
		<< " cf1 < cf2? 1/YES 0/NO " << (cf1 < cf2) << endl
		<< " cf1 == cf2? 1/YES 0/NO " << (cf1 == cf2) << endl
		<< " cf1 != cf2? 1/YES 0/NO " << (cf1 != cf2) << endl
		<< " cf1 >= cf2? 1/YES 0/NO " << (cf1 >= cf2) << endl
		<< " cf1 <= cf2? 1/YES";
	cin >> cf2;

		return 0;
}