C++重载>>运算符奇怪的编译错误

Question

#include <iostream>
#include <string>

using namespace std;

class phonebook
{
    string name;
    string prefix;
public:
    phonebook(string &name, string &prefix)
    {
        this->name = name;
        this->prefix = prefix;
    }

    friend istream &operator>>(istream &in, phonebook &book);
};

istream &phonebook::operator>>(istream &in, phonebook &book)
{
    in >> book.name >> book.prefix;
    return in;
}

int main()
{
    return 0;
}

当我尝试使用g ++ 4.6.1编译此代码时:

"main.cpp:20:错误:'std :: istream&phonebook :: operator >>(std :: istream&,phonebook&)'必须只接受一个参数"

PS:这是非常愚蠢的事情......很明显:S.谢谢你.

Answer 1

operator >>作为成员函数,您不能重载流.任何被定义为成员函数的运算符都将其第一个参数作为对(const)Type的引用,其中Type是您的类名 - 在本例中为phonebook.

你需要改变

istream &phonebook::operator>>(istream &in, phonebook &book)

至

istream & operator>>(istream &in, phonebook &book)