c++运算符重载+实例
题目来源于：http://blog.csdn.net/sxhelijian/article/details/8723847
【项目2拓展2（思考）】这个思考题吊一下大家的胃口：设定义了两个分数类的对象，如CFraction c1, c2。如果定义了int i，我们能用cin>>i>>j;在键盘上输入i和j的值，是否期望用cin>>c1>>c2;输入分数呢？同理，用cout<<c1<<c2;进行输出，可以吗？进一步，用c1+c2得到新的一个分数，用c1/c2实现两个分数的除法，以及其他加、减、比较、求倒数等也是理所当然的。实际上，要自定义分数类，这些直观的基本运算应该要实现，这叫运算符的重载。本任务中用amplify()给出了“放大”运算的一种实现方案，更多内容值得期待地。
首先要说明：有的C++编译系统（如VC++6.0）没有完全实现C++标准，它所提供的后缀.h的头文件不支持把成员函数重载为友元函数，因此在VC++6.0，应把程序的头两行：
#include <iosteam>
using namespace std;
改为一行：#include <iosteam.h> //C语言的风格
这是我自己编写的有关运算符重载的程序：
#include <iostream.h>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); 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);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){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;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 return 0;}贺老师的c++题目对我学习很有帮助，自己以前也学过，为了巩固一下自己所学，找了一些自己以前还不是很明白的题目来回顾c++方面的知识；话说要再把书拿起来（c++primer）看一遍是不太现实了，幸好有像贺老师这样愿意帮助他人学习的好老师，很感谢。而且他出题也是有讲究的。希望广大的朋友们也能从中受益。
参考资料：http://blog.csdn.net/sxhelijian/article/details/7467433
http://blog.csdn.net/zollty/article/details/6697174
http://blog.csdn.net/sxhelijian/article/details/8723847