重载一个simple =运算符 [英] overloading a simple = operator

问题描述

我试图重载我的类的一部分到字符串，我不能得到重载工作。或者，我也将有一个 long long 重载，但我只是假设它将是相同的除了 long long 而不是 string 。

I am trying to overload part of my class to a string and I can't get the overloading to work. Alternatively, I will also have a long long overload, but I just assume that it will be the same excepted for long long instead of string.

class FileData
{
public:
    string extensions_;                 
    unsigned long long containsBytes_;      
};

string& operator = (string& s , FileData& fd)
{
    s= fd.extensions_;
    return s;
}

string extName = fileVector[0];

我得到的错误是ERROR：'operator ='必须是一个成员函数。
我也试过使用istream，但也没有工作。

The error I keep getting is ERROR:'operator=' must be a member function. I also tried using istream but that also didn't work.

任何人都知道我该怎么做？

Anybody know how I could go about this?

推荐答案

您需要一个转换运算子：

class FileData
{
public:

    // Conversion to string
    operator string() const {return extensions_;}

    string extensions_;                 
    unsigned long long containsBytes_;      
};

您只能将赋值运算符重载为类的成员， >到该类的对象。

You can only overload the assignment operator as a member of your class, for the purpose of assigning to an object of that class.

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