第八周上机实践项目3——分数类中的运算符重载（2）

（2）在（1）的基础上，实现分数类中的对象和整型数的四则运算。分数类中的对象可以和整型数进行四则运算，且运算符合交换律。例如：CFraction a(1,3),b; int i=2; 可以完成b=a+i;。同样，可以完成i+a, 45+a, a*27, 5/a等各种运算。

问题及代码

/*
 * Copyright (c) 2015, 烟台大学计算机学院
 * All rights reserved.
 * 文件名称：test.cpp
 * 作    者：辛彬
 * 完成日期：2015 年 4 月 26 日
 * 版 本 号：v1.0
 */
#include<iostream>
using namespace std;
class CFraction
{
private:
    int nume;  // 分子
    int deno;  // 分母
public:
    //构造函数及运算符重载的函数声明
    CFraction() {}
    CFraction(int n,int d):nume(n),deno(d) {}
    void simplify();
    void display();
    CFraction operator+(CFraction &c);
    friend CFraction operator+(CFraction &c,int a);
    friend CFraction operator+(int a,CFraction &c);
    CFraction operator-(CFraction &c);
    friend CFraction operator-(CFraction &c,int a);
    friend CFraction operator-(int a,CFraction &c);
    CFraction operator*(CFraction &c);
    friend CFraction operator*(CFraction &c,int a);
    friend CFraction operator*(int a,CFraction &c);
    CFraction operator/(CFraction &c);
    friend CFraction operator/(CFraction &c,int a);
    friend CFraction operator/(int a,CFraction &c);
    bool operator>(CFraction &c);
    bool operator<(CFraction &c);
    bool operator==(CFraction &c);
    bool operator>=(CFraction &c);
    bool operator<=(CFraction &c);
    bool operator!=(CFraction &c);
};
//重载函数的实现及用于测试的main()函数
void CFraction::simplify()
{
    int i=deno;
    for(; nume%i!=0||deno%i!=0; i--);
    nume=nume/i;
    deno=deno/i;
}
void CFraction::display()
{
    cout<<nume<<"/"<<deno<<endl;
}
CFraction CFraction::operator+(CFraction &c)
{
    int i=deno;
    if(deno==c.deno)
        return CFraction(nume+c.nume,deno);
    else
    {
        for(; i%deno!=0||i%c.deno!=0; i++);
        nume=nume*(i/deno);
        c.nume=c.nume*(i/c.deno);
        deno=i;
        c.deno=i;
        return CFraction(nume+c.nume,deno);
    }
}
CFraction operator+(CFraction &c,int a)
{
    CFraction t(a,1);
    return c+t;
}
CFraction operator+(int a,CFraction &c)
{
    CFraction t(a,1);
    return c+t;
}
CFraction operator-(CFraction &c,int a)
{
    CFraction t(a,1);
    return c-t;
}
CFraction operator-(int a,CFraction &c)
{
    CFraction t(a,1);
    return c-t;
}
CFraction operator*(CFraction &c,int a)
{
    CFraction t(a,1);
    return c*t;
}
CFraction operator*(int a,CFraction &c)
{
    CFraction t(a,1);
    return c*t;
}
CFraction operator/(CFraction &c,int a)
{
    CFraction t(a,1);
    return c*t;
}
CFraction operator/(int a,CFraction &c)
{
    CFraction t(a,1);
    return c/t;
}
CFraction CFraction::operator-(CFraction &c)
{
    int i=deno;
    if(deno==c.deno)
        return CFraction(nume-c.nume,deno);
    else
    {
        for(; i%deno!=0||i%c.deno!=0; i++);
        nume=nume*(i/deno);
        c.nume=c.nume*(i/c.deno);
        deno=i;
        c.deno=i;
        return CFraction(nume-c.nume,deno);
    }
}
CFraction CFraction::operator*(CFraction &c)
{
    return CFraction(nume*c.nume,deno*c.deno);
}
CFraction CFraction::operator/(CFraction &c)
{
    if(deno*c.nume<0)
        return CFraction(-nume*c.deno,-deno*c.nume);
    else
        return CFraction(nume*c.deno,deno*c.nume);
}
bool CFraction::operator>(CFraction &c)
{
    int i=deno;
    if(deno==c.deno)
    {
        if(nume>c.nume)
            return true;
        else
            return false;
    }
    else
    {
        for(; i%deno!=0||i%c.deno!=0; i++);
        nume=nume*(i/deno);
        c.nume=c.nume*(i/c.deno);
        if(nume>c.nume)
            return true;
        else
            return false;
    }
}
bool CFraction::operator<(CFraction &c)
{
    int i=deno;
    if(deno==c.deno)
    {
        if(nume<c.nume)
            return true;
        else
            return false;
    }
    else
    {
        for(; i%deno!=0||i%c.deno!=0; i++);
        nume=nume*(i/deno);
        c.nume=c.nume*(i/c.deno);
        if(nume<c.nume)
            return true;
        else
            return false;
    }
}
bool CFraction::operator==(CFraction &c)
{
    if(*this>c||*this<c)
        return false;
    else return true;
}
bool CFraction::operator>=(CFraction &c)
{
    return !(*this<c);
}
bool CFraction::operator<=(CFraction &c)
{
    return !(*this>c);
}
bool CFraction::operator!=(CFraction &c)
{
    return !(*this==c);
}
int main()
{
    CFraction x(1,3),y(-5,10),s;
    cout<<"分数x=1/3      y=-5/10"<<endl;
    s=x+y;
    cout<<"x+y=";
    s.simplify();
    s.display();
    s=x-y;
    cout<<"x-y=";
    s.simplify();
    s.display();
    s=x*y;
    cout<<"x*y=";
    s.simplify();
    s.display();
    s=x/y;
    cout<<"x/y=";
    s.simplify();
    s.display();

    x.display();
    if (x>y) cout<<"大于"<<endl;
    if (x<y) cout<<"小于"<<endl;
    if (x==y) cout<<"等于"<<endl;
    y.display();
    cout<<endl;

    CFraction c1(5,3),c2;
    //以下建议在调试环境中完成测试，
    c2=c1+5;
    c2=5+c1;

    c2=c1-5;
    c2=5-c1;

    c2=c1*5;
    c2=5*c1;

    c2=c1/5;
    c2=5/c1;
    return 0;
}

运行结果：