class Rational
{
public:
//not correct since this ponit would be used automatically.
//Rational operator+ (const Rational& lhs, const Rational& rhs);
//correct
Rational operator+ (const Rational& rhs);
}
Rational operator+(const Rational& lhs, const Rational& rhs))
作为类的成员函数，重载运算符只能有一个参数,布布扣,bubuko.com
原文：http://www.cnblogs.com/williamwood/p/3807286.html