C++运算符重载 实现有理数（分数）的加减法

在main前面打一个断电，单步调试，整个程序更易理解。

#include<iostream>
#include<string>
#include<stdlib.h>
class Rational
{
public:
	Rational(int num, int denom);//num 分子 denom 分母

	Rational operator+(Rational rhs);//rhs右操作数
	Rational operator-(Rational rhs);
	Rational operator*(Rational rhs);
	Rational operator/(Rational rhs);

	void print();

private:
	void normalize();//对分数的简化

	int numerator;//分子
	int denominator;//分母
};
Rational::Rational(int num, int denom)
{
	numerator = num;
	denominator = denom;
	normalize();
}
//化简
void Rational::normalize()
{
	//分母一定为正
	if (denominator < 0)
	{
		numerator = (-1)*numerator;
		denominator = (-1)*denominator;
	}
	//欧几里得算法
	int a = abs(numerator);
	int b = abs(denominator);
	//求最大公因数
	while (b > 0)
	{
		int t = a % b;
		a = b;
		b = t;
	}
	//分子分母分别除以最大公因数
	numerator = numerator / a;
	denominator = denominator / a;
}
//加
Rational Rational::operator+(Rational rhs)
{
	int a = numerator;
	int b = denominator;
	int c = rhs.numerator;
	int d = rhs.denominator;

	int e = a * d + c * b;
	int f = b * d;
	return Rational(e, f);
}
//减：减一个数等于加上这个数的相反数
Rational Rational::operator-(Rational rhs)
{
	rhs.numerator = -rhs.numerator;
	Rational result = this->operator+(rhs);
	return result;
}
//乘
Rational Rational::operator*(Rational rhs)
{
	int a = numerator;
	int b = denominator;
	int c = rhs.numerator;
	int d = rhs.denominator;

	int e = a * c;
	int f = b * d;
	return Rational(e, f);
}
//除
Rational Rational::operator/(Rational rhs)
{
	int t = rhs.numerator;
	rhs.numerator = rhs.denominator;
	rhs.denominator = t;
	Rational result = this->operator*(rhs);
	return result;
}
//打印
void Rational::print()
{
	if (numerator%denominator == 0)
	{
		std::cout << numerator / denominator;
	}
	else std::cout << numerator << "/" << denominator;
}
int main()
{
	//定义两个数
	Rational f1(-2, 3);
	Rational f2(3, 2);

	//加法
	Rational res = f1 + f2;//f1.+f2，f1是重载运算符的对象本身
	f1.print();
	std::cout << " + ";
	f2.print();
	std::cout << " = ";
	res.print();
	std::cout << std::endl << std::endl;

	//减法
	res = f1 - f2;//f1.-f2，f1是重载运算符的对象本身
	f1.print();
	std::cout << " - ";
	f2.print();
	std::cout << " = ";
	res.print();
	std::cout << std::endl << std::endl;

	//乘法
	res = f1 * f2;//f1./f2，f1是重载运算符的对象本身
	f1.print();
	std::cout << " * ";
	f2.print();
	std::cout << " = ";
	res.print();
	std::cout << std::endl << std::endl;

	//除法
	res = f1 / f2;//f1./f2，f1是重载运算符的对象本身
	f1.print();
	std::cout << " ÷ ";
	f2.print();
	std::cout << " = ";
	res.print();
	std::cout << std::endl << std::endl;

	system("pause");

}