程序不调用正确的重载操作符 [英] program not calling the right overloaded operator

问题描述

我有类目录，其中包含类File的对象和重载的操作符，像这样：

 目录
 {
 std :: vector< char> name，timeOfCreation; 
 std :: vector< File> arr; 
 
 public：
 Directory（std :: string）; 
 Directory（const Directory&）; 
〜Directory（）; 
 
 
目录操作符+ =（文件）; 
目录操作符+ =（目录）; 
目录操作符 -  =（File）; 
目录操作符〜（）; 
文件操作符[]（int）; 
 operator int（）; 
 
 friend bool operator％（Directory，File）; 
 friend bool operator％（Directory，Directory）; 
 friend目录运算符+（目录，目录）; 
 friend目录操作符 - （目录，目录）; 
 friend long int operator +（Directory）; 
 friend std :: ofstream&运算符<< （std :: ofstream& Directory）; 
 
 friend void main（）; 
}; 
  

好，现在问题出现在主要我有

  void main（）
 {
 // make目录的对象d 
 std :: cout< d; 
} 
  

程序现在调用操作符int（），而不是operator< 。因此命令
std :: cout 的行为类似于 std :: cout< （int）d ，它会写出我的目录中的文件数。

这里是运算符的实现<<和int（）：

  Directory :: operator int（）
 {
 return 。尺寸（）​​; 
} 
 
 std :: ofstream&运算符<< （std :: ofstream& out，Directory d）
 {
 //获取三个字段的最大字段宽度
 int widthLeft = 0，widthMiddle = 0，widthRight = 10; 
 std :: vector< File> :: const_iterator i = d.arr.begin（）; 
 for（; i< d.arr.end（）; ++ i）
 {
 if（（int）d.timeOfCreation.size（）> widthLeft）
 widthLeft =（int）d.timeOfCreation.size（）; 
 if（（int）d.name.size（）> widthMiddle）
 widthMiddle =（int）d.name.size（） 
} 
 out<< std :: setw（widthLeft）<<Date& Time of creation; 
 out<< std :: setw（widthMiddle）<<Name; 
 out<< std :: setw（widthRight）<<Total Size\\\
; 
 return out; 
 
} 
  

注意：运算符<尚未完成，我只是测试setw函数，但它仍然应该写出一行。

解决方案

cout 是 ostream ，而不是 ofstream p>

应该工作：

  std :: ostream&运算符<< （std :: ostream& Directory）
  

您可能希望将目录作为参考。 / p>

I've the class Directory which does stuff with objects of class File, and overloaded operators, like this:

class Directory
{
    std::vector<char> name, timeOfCreation;
    std::vector<File> arr;

public:
    Directory(std::string);
    Directory(const Directory&);
    ~Directory();


    Directory operator += (File);
    Directory operator += (Directory);
    Directory operator -= (File);
    Directory operator ~();
    File operator [] (int);
    operator int();

    friend bool operator % (Directory, File);
    friend bool operator % (Directory, Directory);
    friend Directory operator + (Directory, Directory);
    friend Directory operator - (Directory, Directory);
    friend long int operator + (Directory);
    friend std::ofstream& operator << (std::ofstream&, Directory);

friend void main();
};

Ok, now the issue arises when in main i have

void main()
{
     //make object of Directory d
    std::cout << d;
}

The program now calls the operator int() instead of operator <<. Thus the command std::cout <<d acts like std::cout << (int)d, and it writes out the number of Files in my Directory.

Here are the implementations of operators << and int():

Directory::operator int()
{
    return (int)arr.size();
}

std::ofstream& operator << (std::ofstream& out, Directory d)
{
    // get the max field widths for three fields
    int widthLeft = 0, widthMiddle = 0, widthRight = 10;
    std::vector<File>::const_iterator i = d.arr.begin();
    for(; i < d.arr.end(); ++i)
    {
        if((int)d.timeOfCreation.size() > widthLeft)
            widthLeft = (int)d.timeOfCreation.size();
    if((int)d.name.size() > widthMiddle)
            widthMiddle = (int)d.name.size();
    }
    out<<std::setw(widthLeft)<<"Date & Time of creation";
    out<<std::setw(widthMiddle)<<"Name";
    out<<std::setw(widthRight)<<"Total Size\n";
    return out;

}

Note: the operator << isn't finished yet, I'm just testing the setw function, but it still should write out that one line.

解决方案

cout is an ostream, not an ofstream.

Should work:

std::ostream& operator << (std::ostream&, Directory)

You might want to pass the directory as a reference.

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