C++ class 运算符重载不适用于 std::sort

Question

所以我一直在尝试构建一个中值生成器，它接受分数并生成中值，但是目前我似乎无法对我自定义的 RationalNumber class 的向量进行排序。我已经重载了许多运算符（* + / == 等），但是当在其他地方调用内联时它们似乎不起作用。

RationalNumber RationalNumber::operator*(const RationalNumber& r)
{
    RationalNumber result(numerator * r.numerator, denominator * r.denominator);
    result.reduceFraction();
    return result;
}   

RationalNumber RationalNumber::operator*(int x)
{
    RationalNumber result(numerator * x, denominator);
    result.reduceFraction();
    return result;
}

RationalNumber RationalNumber::operator/(const RationalNumber& r)
{
    RationalNumber result(numerator * r.denominator, denominator * r.numerator);
    result.reduceFraction();
    return result;
}

RationalNumber RationalNumber::operator/(int x)
{
    RationalNumber result(numerator, denominator * x);
    result.reduceFraction();
    return result;
}
bool RationalNumber::operator<(const RationalNumber& r)
{
    if(this->floatingPoint < r.floatingPoint)
    {
        return true;
    }

    return false;
}

bool RationalNumber::operator<(int x)
{
    if(floatingPoint < (double) x)
    {
        return true;
    }

    return false;
}

bool RationalNumber::operator>(const RationalNumber& r)
{
    if(floatingPoint > r.floatingPoint)
    {
        return true;
    }
    return false;
}

bool RationalNumber::operator>(int x)
{
    if(floatingPoint > (double) x)
    {
        return true;
    }
    return false;
}

RationalNumber RationalNumber::operator+(const RationalNumber& r)
{
    RationalNumber result((numerator * r.denominator)+(r.numerator*denominator),denominator * r.denominator);
    result.reduceFraction();
    return result;
}

RationalNumber RationalNumber::operator+(int x)
{
    RationalNumber result(numerator * x,denominator);
    return result;
}

所以这里我有一个 class 用来表示带有重载运算符的有理数，这些运算符旨在执行算术运算。但是，当在主要 class 中执行以下操作时：

RationalNumber medianCalculator(std::vector<RationalNumber*> &listOfRationalNumbers)
{
    std::sort(listOfRationalNumbers.begin(),listOfRationalNumbers.end());
    if(!(listOfRationalNumbers.size() % 2)){
        return ((RationalNumber(*listOfRationalNumbers.at((listOfRationalNumbers.size()/2) +1)) + (RationalNumber(*listOfRationalNumbers.at(listOfRationalNumbers.size()/2))) / 2));
    } else {
        return RationalNumber(*listOfRationalNumbers.at(listOfRationalNumbers.size() +1));
    }
}

首先，它似乎生成了一个超出范围的异常，但更重要的是，运算符重载似乎没有起作用，因为 std::sort 调用似乎不起作用或算术运算。

Answer 1

肯定是运算符重载不正确。例如，这段代码会产生意想不到的结果：

RationalNumber num(1, 1);
num *= 2;
// num is still 1/1

正确的实现应该是：

RationalNumber& RationalNumber::operator*(int x)
{
    numerator *= x;
    reduceFraction();
    return *this;
}

其余的方法应该相应地实现。

C++ class 运算符重载不适用于 std::sort

C++ class operator overloads don't work with std::sort

c++

sorting

operator-overloading

std

operators