嗨，我对 C++ 比较陌生，在学习了一些 Java 基础知识后，我才开始学习它。我有预先存在的代码，如果它使>>操作员过载，但是在观看了许多教程并试图理解这个问题之后，我想我会在这里问。
合理的cpp文件：
#include "Rational.h"
#include <iostream>
Rational::Rational (){
}
Rational::Rational (int n, int d) {
n_ = n;
d_ = d;
}
/**
* Creates a rational number equivalent to other
*/
Rational::Rational (const Rational& other) {
n_ = other.n_;
d_ = other.d_;
}
/**
* Makes this equivalent to other
*/
Rational& Rational::operator= (const Rational& other) {
n_ = other.n_;
d_ = other.d_;
return *this;
}
/**
* Insert r into or extract r from stream
*/
std::ostream& operator<< (std::ostream& out, const Rational& r) {
return out << r.n_ << '/' << r.d_;
}
std::istream& operator>> (std::istream& in, Rational& r) {
int n, d;
if (in >> n && in.peek() == '/' && in.ignore() && in >> d) {
r = Rational(n, d);
}
return in;
}}
Rational.h 文件：
#ifndef RATIONAL_H_
#define RATIONAL_H_
#include <iostream>
class Rational {
public:
Rational ();
/**
* Creates a rational number with the given numerator and denominator
*/
Rational (int n = 0, int d = 1);
/**
* Creates a rational number equivalent to other
*/
Rational (const Rational& other);
/**
* Makes this equivalent to other
*/
Rational& operator= (const Rational& other);
/**
* Insert r into or extract r from stream
*/
friend std::ostream& operator<< (std::ostream &out, const Rational& r);
friend std::istream& operator>> (std::istream &in, Rational& r);
private:
int n_, d_;};
#endif
该函数来自一个名为 Rational 的预先存在的类，它接受两个ints 作为参数。这是重载的函数>>：
std::istream& operator>> (std::istream& in, Rational& r) {
int n, d;
if (in >> n && in.peek() == '/' && in.ignore() && in >> d) {
r = Rational(n, d);
}
return in;
}
在看过一些教程之后，我正在尝试像这样使用它。（我得到的错误"Ambiguous overload for operator>>是std::cin>>n1：
int main () {
// create a Rational Object.
Rational n1();
cin >> n1;
}
就像我说的那样，我对整个重载运算符的事情是新手，并且认为这里的某个人能够为我指出如何使用这个函数的正确方向。