Question

我无法理解这个错误。这个错误不在我正在调试的类中。 （是吗？） 错误是：

c:\program files\microsoft visual studio 10.0\vc\include\fstream(890): error    C2248: 'std::basic_ios<_Elem,_Traits>::basic_ios' : cannot access private member declared in class 'std::basic_ios<_Elem,_Traits>'
1>          with
1>          [
1>              _Elem=char,
1>              _Traits=std::char_traits<char>
1>          ]
1>          c:\program files\microsoft visual studio 10.0\vc\include\ios(176) : see     declaration of 'std::basic_ios<_Elem,_Traits>::basic_ios'
1>          with
1>          [
1>              _Elem=char,
1>              _Traits=std::char_traits<char>
1>          ]
1>          This diagnostic occurred in the compiler generated   function 'std::basic_ifstream<_Elem,_Traits>::basic_ifstream(const std::basic_ifstream<_Elem,_Traits> &)'
1>          with
1>          [
1>              _Elem=char,
1>              _Traits=std::char_traits<char>
1>          ]
 ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

我收到此错误的原因是什么？代码太冗长而无法发布。 我正在使用的编译器是 Microsoft visual c ++ 2010 express

编辑：

    void HostelManager::guestMonitor() {
        system("cls");

        cout << "Name of the guest : "; // cin guest
        cin.ignore();
        getline( cin , guestName );

        cout << "\nWhom to meet : ";   // to whom the guest wants to meet
        cin.ignore();
        getline( cin , fullName ); 

        string pathGND = "d:/HostelManager/studentDetails/groundFloor/" + fullName + ".txt";
        string pathFST = "d:/HostelManager/studentDetails/firstFloor/" + fullName + ".txt";
        string pathSND = "d:/HostelManager/studentDetails/firstFloor/" + fullName + ".txt";
        ifstream checkStudentGND( pathGND );
        ifstream checkStudentFST( pathFST );
        ifstream checkStudentSND( pathSND );
        string x = "Floor";

        if( checkStudentGND ) {
            ifstream readRoom( pathGND );
            readRoom >> fullName >> fatherName >> permanentAddress >> postalAddress >> x >> roomNumberToBeAlloted_GND;
            int hisRoomNumber = roomNumberToBeAlloted_GND;
            readRoom.close();
            storeGuestData( hisRoomNumber , fullName );  // call to store guest data
        } else if( checkStudentFST ) {
            ifstream readRoom( checkStudentFST );
            readRoom >> fullName >> fatherName >> permanentAddress >> postalAddress >> x >> roomNumberToBeAlloted_FST;
            int hisRoomNumber = roomNumberToBeAlloted_FST;
            storeGuestData( hisRoomNumber , fullName );  // call to store guest data
        } else if( checkStudentSND ) {
            ifstream readRoom( checkStudentSND );
            readRoom >> fullName >> fatherName >> permanentAddress >> postalAddress >> x >> roomNumberToBeAlloted_SND;
            int hisRoomNumber = roomNumberToBeAlloted_SND;
            storeGuestData( hisRoomNumber , fullName );  // call to store guest data
        } else {
            string sorryMSG = "Sorry ! The student is not in this hostel"                  cout << sorryMSG << endl ;
        }
   }

被叫函数：

    void HostelManager::storeGuestData( int hisRoomNumber , string hisName ) {
        cout << "\nVisitor's Address : ";  // cin visitor address
        string visitorAddress;
        getline( cin , visitorAddress );

        cout << "\nRelation with the student : ";   // cin relation with student
        string relation;
        getline( cin , relation );

        cout << "\nEnter Month";    // cin enter month
        short month;
        cin >> month;

        cout << "\nEnter Date";    // cin enter date
        short date;
        cin >> date;

        cout << "\nYou can meet " << hisName << " in room number " << hisRoomNumber << endl ;

        string visitorPath = "d:/HostelManager/GuestMonitor/" + fullName + ".txt" ;
        ofstream guestEntry( visitorPath );
        guestEntry << "Name of Visitor : " << guestName << endl ;
        guestEntry << "To meet : " << fullName << endl ;
        guestEntry << "Address of visitor : " << visitorAddress << endl ;
        guestEntry << "Relation with the student : " << relation << endl ;
        guestEntry << "Month : " << month << endl ;
        guestEntry << "Date : " << date << endl ; 
        guestEntry.close();
        cout << "\n\n\n\nData successfully inserted";
    }

数据成员：

    private:
        string fullName;
        string fatherName;
        string permanentAddress;
        string postalAddress;
        int mobileNumbers[2][10];
        double percentageMarks;
        int roomNumber;
        int roomNumberToBeAlloted_GND ;
        int roomNumberToBeAlloted_FST ;
        int roomNumberToBeAlloted_SND ;
        string preferredFloor;
        string guestName;
        string studentFined;
        string complaintAgainst;
        string receiverOfEmail;
        string senderOfEmail;
        string subject;

    public:
        void guestMonitor();
        void storeGuestData( int hisRoomNumber , string hisName );

Answer 1

您正在尝试复制流，这是不可能的。

为了帮助您避免这种情况，其中一个基类具有私有拷贝构造函数。

Answer 2

违规行是，

ifstream readRoom( checkStudentFST );

和

ifstream readRoom( checkStudentSND );

您尝试复制现有流，而不是使用文件名打开它。

Answer 3

根据您的错误，我可以猜测您是否尝试使用operator <<（或operator >>）为您自己的fstream重叠ostream或class对象。

不知何故，您错过了operator <<作为class的朋友的功能。您的代码应该是like this snippet。请仔细查看目标public的数据成员class。

Answer 4

如果您在构造函数中设置类参数（正在创建对象的副本），则会出现此问题，如下所示：

class Test
{
public:
    Test() {}
    Test(FileHandler fh_) : fh(fh_) {}
    // ...
private:
    FileHandler fh;
};

如果FileHandler类包含一个文件流成员，您将收到错误，就像我一样。

解决方案：将构造函数参数从FileHandler fh_更改为FileHandler* fh_。

错误C2248：'std :: basic_ios＆lt; _Elem，_Traits＆gt; :: basic_ios'：无法访问类'std :: basic_ios＆lt; _Elem，_Traits＆gt;'中声明的私有成员

4 个答案: