【C++】实现一个有理数类

有理数：指所有可以用两个整数的商来表示的数

Rational.h

Rational类的接口

#ifndef _RATIONAL_H
#define _RATIONAL_H

#include <iostream>
#include <string>

class Rational {
public:
    Rational();
    Rational(int n);
    Rational(int x, int y);

    std::string toString();

    friend Rational operator+(Rational r1, Rational r2);
    friend Rational operator-(Rational r1, Rational r2);
    friend Rational operator*(Rational r1, Rational r2);
    friend Rational operator/(Rational r1, Rational r2);

private:
    int num; // 分子
    int den; // 分母


};

std::ostream &operator<<(std::ostream & os, Rational rat);

Rational operator+(Rational r1, Rational r2);
Rational operator-(Rational r1, Rational r2);
Rational operator*(Rational r1, Rational r2);
Rational operator/(Rational r1, Rational r2);

#endif //LEETCODE_RATIONAL_H

Rational.cpp

Rational类的实现

//
// Created by NFYD on 10/6/2022.
//

#include "rational.h"

#include <iostream>
#include <string>
#include <cstdlib>

using namespace std;

int gcd(int x, int y);

Rational::Rational() {
    num = 0;
    den = 1;
}

Rational::Rational(int n) {
    num = n;
    den = 1;
}

Rational::Rational(int x, int y) {
    if (y == 0) printf("Rational: Division by zero!");
    if (x == 0) {
        num = 0;
        den = 1;
    } else {
        int g = gcd(abs(x), abs(y));
        num = x / g;
        den = abs(y) / g;
        if (y < 0) num = -num;
    }
}

string Rational::toString() {
    if (den == 1) {
        return integerToString(num);
    } else {
        return integerTostring(num) + "/" + integrToString(den);
    }
}

ostream & operator<<(ostream & os, Rational rat) {
    return os << rat.toString();
}

Rational operator+(Rational r1, Rational r2) {
    return Rational(r1.num * r2.den + r2.num * r1.den, r1 .den * r2.den);
}

Rational operator-(Rational r1, Rational r2) {
    return Rational(r1.num * r2.den - r2.num * r1.den, r1 .den * r2.den);
}

Rational operator*(Rational r1, Rational r2) {
    return Rational(r1.num * r2.num, r1.den * r2.den);
}

Rational operator/(Rational r1, Rational r2) {
    return Rational(r1.num * r2.den, r1.den * r2.num);
}

int gcd(int x, int y) {
    int r = x % y;
    while (r != 0) {
        x = y;
        y = r;
        r = x % y;
    }
    return y;
}

/* gcd也可以写成这种
int gcd(int a, int b) {
    return b ? gcd(b, a % b) : a;
}
*/