我查看过许多其他涉及重载*运算符的帖子，我仍然无法看到问题。
#include <iostream>
#include <string>
#include <cmath>
using namespace std;
class Fraction{
private:
int num, den;
public:
void set(int n, int d);
void setNum(int newNum);
void setDen(int newDen);
Fraction add(Fraction other);
Fraction simplify();
Fraction(int new_Num = 0, int new_Den = 0){
num = new_Num;
den = new_Den;
};
void output(Fraction& f);
void cleanerFunction(Fraction& f);
int gcd();
Fraction reduce();
friend ostream& operator <<(ostream& os, Fraction& f);
friend istream& operator >>(istream& in, Fraction& f);
friend Fraction operator + ( const Fraction&, const Fraction& );
friend inline Fraction operator - ( const Fraction&, const Fraction& );
friend Fraction operator * ( const Fraction&, const Fraction& );
friend Fraction operator / ( const Fraction&, const Fraction& );
friend bool operator < ( const Fraction&, const Fraction& );
friend bool operator <= ( const Fraction&, const Fraction& );
friend bool operator > ( const Fraction&, const Fraction& );
friend bool operator >= ( const Fraction&, const Fraction& );
friend bool operator == ( const Fraction&, const Fraction& );
};
int gcd(int x, int y);
Fraction reduce(Fraction f);
void reduce(Fraction& f);
Fraction operator + ( const Fraction& f, const Fraction& r){
int temp_Num, temp_Den;
temp_Num = (f.num * r.den) + (f.den * r.num);
temp_Den = (f.den * r.den);
Fraction temp_Frac(temp_Num, temp_Den);
temp_Frac.cleanerFunction(temp_Frac);
return temp_Frac;
};
Fraction operator - ( const Fraction& f, const Fraction& r){
int temp_Num, temp_Den;
temp_Num = (f.num * r.den) - (f.den * r.num);
temp_Den = (f.den * r.den);
Fraction temp_Frac(temp_Num, temp_Den);
temp_Frac.cleanerFunction(temp_Frac);
return temp_Frac;
};
Fraction operator * ( const Fraction& f, const Fraction& r){
int temp_Num, temp_Den;
temp_Num = (f.num * r.num);
temp_Den = (f.den * r.den);
Fraction temp_Frac(temp_Num, temp_Den);
temp_Frac.cleanerFunction(temp_Frac);
return temp_Frac;
};
Fraction operator / ( const Fraction& f, const Fraction& r){
int temp_Num, temp_Den;
temp_Num = (f.num * r.den);
temp_Den = (f.den * r.num);
Fraction temp_Frac(temp_Num, temp_Den);
return temp_Frac;
};
bool operator < ( const Fraction& f, const Fraction& r){
return (f.num * r.den) < (r.num * f.den);
};
bool operator <= ( const Fraction& f, const Fraction& r){
return (f.num * r.den) <= (r.num * f.den);
};
bool operator > ( const Fraction& f, const Fraction& r){
return (f.num * r.den) > (r.num * f.den);
};
bool operator >= ( const Fraction& f, const Fraction& r){
return (f.num * r.den) >= (r.num * f.den);
};
bool operator == ( const Fraction& f, const Fraction& r ){
return (f.num * r.den) == (r.num * f.den);
};
ostream& operator <<(ostream& os, Fraction& f)
{
f.output(f);
return os;
}
istream& operator >>(istream& in, Fraction& f)
{
char ch;
int temp_Num, temp_Den;
in >> temp_Num >> ch >> temp_Den;
f.set(temp_Num, temp_Den);
f.cleanerFunction(f);
return in;
}
int main()
{
cout <<"HELLO\n";
cout << "Testing declarations " << endl;
cout << "Fraction x, y(2), z(-5,-6), w(1,-3);" << endl;
Fraction x, y(2), z(-5,-6), w(1,-3);
cout << "z = " << z << ", y = " << y << ", z = " << z << ", w = " << w << endl;
cout << "Testing >> overloading: \nEnter a fraction in the format " << "integer _numerator/integer _denominator" << endl;
cin >> x;
cout << "You entered the equivalent of: " << x << endl;
//cout << z << " - (" << w << ") = " << z - w << endl;
cout << "Testing the constructor and normalization routines: " << endl;
y =Fraction(-128, -48);
cout << "y =Fraction(-128, -48) outputs as " << y << endl;
y =Fraction(-128, 48);
cout << "y =Fraction(-128, 48 ) outputs as " << y << endl;
y = Fraction(128,-48);
cout << "y = Fraction(128, -48) outputs as " << y << endl;
Fraction a(1,1);
cout << "Fraction a(1,1); a outputs as: " << a << endl;
Fraction ww = y*a;
cout << y << " * " << a << " = " << ww << endl;
w = Fraction(25,9);
z = Fraction(3,5);
cout << "Testing arithmetic and relational operator overloading" << endl;
//cout << w << " * " << z << " = " << w * z << endl;
//cout << w << " + " << z << " = " << w + z << endl;
//cout << w << " - " << z << " = " << w - z << endl;
//cout << w << " / " << z << " = " << w / z << endl;
cout << w << " < " << z << " = " << (w < z) << endl;
cout << w << " < " << w << " = " << (w < w) << endl;
cout << w << " <= " << z << " = " << (w <= z) << endl;
cout << w << " <= " << w << " = " << (w <= w) << endl;
cout << w << " > " << z << " = " << (w > z) << endl;
cout << w << " > " << w << " = " << (w > w) << endl;
cout << w << " >= " << z << " = " << (w >= z) << endl;
cout << w << " >= " << w << " = " << (w >= w) << endl;
w = Fraction(-21,9);
z = Fraction(3,5);
//cout << w << " * " << z << " = " << w * z << endl;
//cout << w << " + " << z << " = " << w + z << endl;
//cout << w << " - " << z << " = " << w - z << endl;
//cout << w << " / " << z << " = " << w / z << endl;
cout << w << " < " << z << " = " << (w < z) << endl;
cout << w << " < " << w << " = " << (w < w) << endl;
cout << w << " <= " << z << " = " << (w <= z) << endl;
cout << w << " <= " << w << " = " << (w <= w) << endl;
cout << w << " > " << z << " = " << (w > z) << endl;
cout << w << " > " << w << " = " << (w > w) << endl;
cout << w << " >= " << z << " = " << (w >= z) << endl;
cout << w << " >= " << w << " = " << (w >= w) << endl;
return 0;
return 0;
}
Fraction Fraction::add(Fraction other){
Fraction result;
result.num = num*other.den + other.num *den;
result.den = den*other.den;
return result;
}
Fraction Fraction::simplify(){
Fraction f1;
f1.num = 4; f1.den=5;
return f1;
}
int gcd(int x, int y){
if( y<0)
y =-y;
if(x % y == 0)
return y;
else
return gcd(y, x%y);
}
int Fraction::gcd(){
Fraction temp;
if( den<0)
den =-den;
if(num % den == 0)
return den;
else{
temp.num =den;
temp.den= num%den;
return temp.gcd();
}
}
void Fraction::set(int n, int d){
num = n;
den = d;
}
void Fraction::setNum(int newNum){
num = newNum;
}
void Fraction::setDen(int newDen){
den = newDen;
}
Fraction Fraction::reduce(){
Fraction temp;
temp.set(num,den);
int m = temp.gcd();
num /= m;
den /= m;
}
Fraction reduce(Fraction f){
int m = f.gcd();
}
void reduce(Fraction& f){
}
void Fraction::output(Fraction& f){
f.cleanerFunction(f);
cout << num << "/"<< den;
}
void Fraction::cleanerFunction(Fraction& f){
int temp_Num = num;
int temp_Den = den;
if ((temp_Num != 0) && (temp_Den == 0))
temp_Den = 1;
if ((temp_Num > 0) && (temp_Den < 0 )){
temp_Den = abs(temp_Den);
temp_Num = -temp_Num;
};
if (( temp_Num < 0) && (temp_Den < 0)){
temp_Den = abs(temp_Den);
temp_Num = abs(temp_Num);
};
num = temp_Num;
den = temp_Den;
}
有相关代码，如果您需要更多我可以发布。代码 * cout＆lt;＆lt; w * z＆lt;＆lt; ENDL; * 并且Main（）中的所有内容都无法修改，其他一切都可以。
我得到的错误是 错误：无法将'std :: ostream {aka std :: basic_ostream}'左值绑定到'std :: basic_ostream＆amp;＆amp;'
Main（）中注释掉的行是我收到错误消息的行。所以我遇到了（+， - ，*，/）运算符的问题。我想看看*，然后我可以回去并对其余的那些应用相同的修复。
答案 0 :(得分：1)
您在cout << w * z << endl;收到错误消息，因为没有operator<<的重载，它将类Fraction作为参数。尝试定义此重载：
std::ostream& operator<<(std::ostream& os, const Fraction& f)
{
return os << f.den << "/" << f.num;
}
并将以下行添加到class Fraction的定义中，以使den和num可用于此功能：
friend std::ostream& operator<<(std::ostream& os, const Fraction& f);