運營商的ambigious過載>>'在'getfile >>點'

Question

當我運行此操作時，我不斷收到以下錯誤。任何幫助？

ambigious overload for ‘operator >> ’ in ‘getfile >> point’ 

這是我在第對象代碼

istream& pp::operator >> (istream& in) 
{ 
    //error msg 
    string msg = "Error. Output from file, String is found instead of integer. Please check file for errors\n"; 

    //ignore everything till next record 
    in.ignore(256, '['); 

    //store x cordinate 
    in >> x; 
    if(in.fail()){throw msg;} 

    //ignore everything till next record 
    in.ignore(256, ','); 

    //store y cordinate 
    in >> y; 
    if(in.fail()){throw msg;} 

    //ignore the rest of the records till next line 
    in.ignore(256, '\n'); 

    return in; 

}//end of operator >> method 

這是我的主要

{ 
    ifstream getfile; 
    //get filename to input data into system 
    cout << "\nPlease enter filename : "; 
    cin >> file; 
    getfile.open(file, ios::in); 

    pp pointObject(); 
    getfile >> point; 
} 

這是我pp.h結構，其中你們希望看到的。

class pp 
    { 
    public: 
    //constructor 
    pp(); 
    pp(int, int); 
    pp(const Point2D &pd); 

    //operator overloaded methods 
    virtual pp operator-(pp pd); 
    virtual bool operator<(pp pd) const; 
    virtual bool operator>(pp pd) const; 
    virtual bool operator==(pp pd); 
    virtual ostream& operator<<(ostream& o) const; 
    virtual istream& operator>>(istream& in;  

    //accessor,mutator methods 
    int getX() const; 
    int getY() const; 

    void setX(int); 
    void setY(int); 

    protected: 
    int x; 
    int y; 
    }; 
    #endif 

Answer 1

的operator>>不能是類的成員，因爲這樣可以給它以錯誤的順序的參數。您必須考慮所有成員函數（和運算符）的隱含this參數。

簽名應該是istream& operator>>(istream& in, pp& point)，以便在getfile >> point;中使用它。

Answer 2

的定義您operator >>應該是：

istream& operator>>(istream& in, pp &p) 

然後，在函數體，你應該指定讀p.x和p.y的x和y值。

Answer 3

我建議寫一個獨立的運算符重載

注意也回覆：處理流錯誤和使用異常，請參閱try/catch throws error

friend istream& pp::operator>> (istream& in, pp& pointObject) 
{ 
    //error msg 
    const string msg = "ErPoint2Dror. Output from file, String is found instead of integer. Please check file for errors\n"; 

    //ignore everything till next record 
    in.ignore(256, '['); 

    int x,y; 

    //store x cordinate 
    in >> x; 
    if(in.fail()) 
    { 
     throw msg; 
    } 

    //ignore everything till next record 
    in.ignore(256, ','); 

    //store y cordinate 
    in >> y; 
    if(in.fail()) 
    { 
     throw msg; 
    } 

    //ignore the rest of the records till next line 
    in.ignore(256, '\n'); 

    pointObject.x = x; 
    pointObject.y = y; 

    return in; 
}//end of operator >> method 

Answer 4

重載流運營商最好的辦法是保持他們作爲朋友。

在你的PP類聲明：

friend istream& operator >>(istream& in, pp& obj); 

在你的CPP文件：

istream& operator>>(istream &in, pp& obj) 
{ 
    // Your code 
}