我得到奇怪的通知,我正在使用私有的类成员 - 这是完全有效的,但我虽然我被允许这样做,因为我确实说我正在使用的方法是友好的。
看看这个:
#include <iostream>
using namespace std;
class complex {
private:
double Re, Im;
public:
complex(): Re(0.0), Im(0.0){}
complex(double Re, double Im): Re(Re), Im(Im){}
double getRe() const { return Re; }
double getIm() const { return Im; }
friend complex operator+(const complex&, const complex&);
friend ostream& operator<<(ostream&, const complex&);
friend istream& operator>>(istream &, const complex &); // FRIENDLY FUNCTION
};
complex operator+(const complex& a, const complex& b) {
double r, i;
r = a.getRe()+ b.getRe();
i = a.getIm() + b.getIm();
return complex(r, i);
}
ostream& operator<<(ostream& out, const complex &a) {
out << "(" << a.getRe() << ", " << a.getIm() << ")" << endl;
return out;
}
istream &operator>>(istream &in, complex &c)
{
cout<<"enter real part:\n";
in>>c.Re; // ** WITHIN THIS CONTEXT ERROR **
cout<<"enter imag part: \n";
in>>c.Im; // ** WITHIN THIS CONTEXT ERROR **
return in;
}
int main(void) {
complex a, b,c;
cin >> a;
cin >> b;
c = a+b;
cout << c;
}
我是否应该在类中声明某种setFunction以获取私有值?
答案 0 :(得分:5)
istream& operator>>(istream &, const complex &);
与
不同istream &operator>>(istream &in, complex &c);
将作为锻炼的差异发现给读者。