没有运算符“=”匹配这些操作数。我已经超载了，但它似乎无法正常工作

Question

我已经重载了“=”运算符来接受我的 class 理性的 objects，但它似乎不起作用。这是我的 headers 和我的 class 定义

#include <iostream>
#include <assert.h>
#include <fstream>
using namespace std;

class rational {
public:

rational();
rational(int numerator, int denominator);
rational(const rational& r);

int numerator() const;
int denominator() const;

const rational& operator = (const rational& rhs);  //this is what I'm having issues with

private:

int myNumerator, myDenominator;

void reduce();
};

这是我的重载实现（我在 main 下面）：

const rational& rational::operator = (const rational& rhs) {
if (*this != rhs) { //added asterisk, otherwise operator would not work
    myNumerator = rhs.numerator();
    myDenominator = rhs.denominator();
}
return *this;
}

下面是我在以下实现中使用“=”运算符时遇到的问题：

istream& operator>>(istream& is, const rational& r) {
    char divisionSymbol;
    int numerator = 0, denominator = 0;

    is >> numerator >> divisionSymbol >> denominator;
    assert(divisionSymbol == '/');
    assert(denominator != 0);
    rational number(numerator, denominator);
    r = number; /* Error: no operator matches these operands (more specifically no operator found
 which takes a left-hand operand of type 'const rational') but I am unsure how to fix that as the
 assignment operator only takes one parameter (unless I am mistaken)*/
    return is;
}

我这辈子都想不出什么是行不通的，可能是语法问题？我的教授非常 old-school 所以可能是一种过时的做法？如有任何提示，我们将不胜感激。

Answer 1

问题不在于“=”运算符重载函数。问题在于“>>”运算符重载函数。您将 r 声明为 const 引用参数，并试图通过向其分配 'number' 对象来修改它。

如果你想修改'r'，你应该声明'r'作为参考，如下所示。

istream& operator>>(istream& is, rational& r)

没有运算符“=”匹配这些操作数。我已经超载了，但它似乎无法正常工作

No operator "=" matches these operands. I have overloaded it but it doesn't seem to be working properly

c++

class

operator-overloading

assignment-operator