Question

#include <iostream>
using namespace std;
#include "fraction.h"

int main()
{
    Fraction f(1,2);
    Fraction g(1,2);

     if (f > g)  cout << f << " > " << g << endl;

    return 0;
 }

Fraction::Fraction()
{
    //ctor
    m_top = 0;
    m_bottom = 1;
}

Fraction::Fraction(int t, int b)
{
    //ctor
    m_top = t;
    m_bottom = b;
    reduce();
}

bool Fraction operator>(const Fraction& l, const Fraction& r)
{
    int a = l.getTop();
    int b = l.getBottom();
    int c = r.getTop();
    int d = r.getBottom();
    if ((a*d-c*b) > (b*d))

    return true;
}

void Fraction::reduce()
{
    int g=gcf(m_top, m_bottom);
    m_top /= g;
    m_bottom /= g;
}

/// recursive
int Fraction::gcf(int m, int n)
{
    if (n == 0) return m;
    return gcf(n, m % n);
}

#ifndef FRACTION_H
#define FRACTION_H

#include <iostream>

using namespace std;

class Fraction
{

    public:
        Fraction();
        Fraction(int, int);
        int getTop() {return m_top;}
        int getBottom() {return m_bottom;}
        void set(int t, int b) {m_top=t; m_bottom=b; reduce();}
        Fraction( Fraction t, Fraction b);
    protected:
    private:
        void reduce();
        int gcf(int, int);

        int m_top;
        int m_bottom;



};

ostream& operator<<(ostream&, Fraction);
Fraction operator+(Fraction l, Fraction r);
Fraction operator*(Fraction l, Fraction r);
Fraction operator/(Fraction l, Fraction r);
Fraction operator>(Fraction l, Fraction r);
Fraction operator>=(Fraction l, Fraction r);
Fraction operator<(Fraction l, Fraction r);
Fraction operator<=(Fraction l, Fraction r);
Fraction operator==(Fraction l, Fraction r);
Fraction operator!=(Fraction l, Fraction r);


#endif // FRACTION_H

日志说int main（）发生错误错误：无法转换＆＃39;运算符＆gt;（f，g）＆＃39;来自＆＃39;分数＆＃39;到了布尔＆＃39;

有人可以告诉我我做错了什么，并修复我的代码？ bool语句有问题吗？如果是这样我该怎么办？

Answer 1

Fraction operator>(Fraction l, Fraction r);
Fraction operator>=(Fraction l, Fraction r);
Fraction operator<(Fraction l, Fraction r);
Fraction operator<=(Fraction l, Fraction r);
Fraction operator==(Fraction l, Fraction r);
Fraction operator!=(Fraction l, Fraction r);

这些运算符应返回布尔值，而不是Fraction：

bool operator>(Fraction l, Fraction r);
bool operator>=(Fraction l, Fraction r);
bool operator<(Fraction l, Fraction r);
bool operator<=(Fraction l, Fraction r);
bool operator==(Fraction l, Fraction r);
bool operator!=(Fraction l, Fraction r);

编译器告诉您无法将返回值Fraction转换为bool，因为这些操作符需要它。

修改

此外，这些运营商的预期签名是：

bool operator>(const Fraction& l, const Fraction& r); bool operator>=(const Fraction& l, const Fraction& r); bool operator<(const Fraction& l, const Fraction& r); bool operator<=(const Fraction& l, const Fraction& r); bool operator==(const Fraction& l, const Fraction& r); bool operator!=(const Fraction& l, const Fraction& r);

const 因为这些操作符不应修改输入值，并且引用 & 是为了避免复制整个对象。

错误：无法将运算符从小数转换为布尔值

1 个答案: