c++写的分数类，可进行运算操作和比较操作及和浮点数据的转换操作

#include "fraction.h" #include <math.h> Fraction::Fraction() { top = 0; bottom = 1; } Fraction::Fraction(int a) { top = a; bottom = 1; } Fraction::Fraction(int a, int b) { top = a; bottom = b; normalize(); } void Fraction::normalize() { int a =top; int b = bottom; if (top*bottom == 0) return; int sign = 1; if(a*b < 0) sign = -1; int A = abs(a); int B = abs(b); int temp; // get the greatest common denominator if(A < B){ temp = A; A = B; B = temp; } while(A%B != 0){ temp = A%B; A = B; B = temp; } top = sign *abs(a) /B; bottom = abs(b) / B; } Fraction::~Fraction() { //dtor } Fraction Fraction::operator +(Fraction & frac) { int a1 = frac.gettop(); int b1 = frac.getbottom(); return Fraction(this->top*b1+ this->bottom*a1, b1*this->bottom); } Fraction Fraction::operator -(Fraction & frac) { int a1 = frac.gettop(); int b1 = frac.getbottom(); return Fraction(this->top*b1 - this->bottom* a1, b1*this->bottom); } Fraction Fraction::operator *(Fraction & frac) { int a1 = frac.gettop(); int b1 = frac.getbottom(); return Fraction(this->top* a1, b1 *this->bottom); } Fraction Fraction::operator /(Fraction & frac) { int a1 = frac.gettop(); int b1 = frac.getbottom(); return Fraction(this->top * b1 , a1*this->bottom); } std::ostream& operator<<(std::ostream & os , const Fraction &F ) { if (F.bottom == 1) os <<F.top; else os << F.gettop() <<"/" << F.getbottom(); return os; } std::istream& operator >>(std::istream & os , Fraction &F ) { int a, b; char c; os >> a>>c>> b; F.top = a; F.bottom = b; F.normalize(); return os; } double Fraction::toDouble() const { return (top+0.0)/ bottom; }