链接器错误:对虚函数表的未定义引用

Linker error: undefined reference to vtable

本文关键字：未定义 引用 函数 错误 链接      更新时间：2023-10-16

我希望你能帮我解决这个问题，这个程序是一个剧院预订程序。

main.cpp 

{
#include <cstdlib>
#include <iostream>
#include "headerMachine.h"
using namespace std;
int main(int argc, char *argv[])
{
    Machine machineCall;
    Movies moviesCall;
    machineCall.menu();
    moviesCall.chooseMovie();
    system("pause");
    return 0;
}

header.h 

    #include <string>
#include <iostream>
using namespace std;
class Machine
    {
        public:
            void menu(); //
            virtual void reserveSeats();
            virtual void availableSeats();
            void ticketSales();
        private:
            int task;
        };
class Movies: public Machine
    {
        public:
            void chooseMovie(); //
            void setTitle();
            void timeSlot();
            void receipt();
            //Inheritance
            void reserveSeats();//
            void availableSeats();

        protected:
            int chosenMovie;
            int rowNum;
            int seatNum;
            int seatsThHo[10][10];
            int seatsROG[10][10];
            int seatsHoTr[10][10];
        };

imp.cpp 

    #include <cstdlib>
#include <iostream>
#include "headerMachine.h"
using namespace std;
const char RESERVED = '*';
const char VACANT = 'o';
void Machine::menu()
{
    cout<<"n  [1]Reserve Seats  ";
    cout<<"n  [2]Available Seats  ";
    cout<<"n  [3]View Ticket Sales  ";
    cout<<"n  [0]Exit  ";
    cout<<"nnChoose task number: ";
    cin>>task;
}
void Movies::chooseMovie()
{
    cout<<"n [1]The Hobbit ";
    cout<<"n [2]Rise of the Guardians ";
    cout<<"n [3]Hotel Transylvania ";
    cout<<"n [0]Back ";
    cout<<"nn From what movie: ";
    cin>>chosenMovie;
}
void Movies::reserveSeats()
{
    cout<<"nEnter row #: ";
    cin>>rowNum;
    cout<<"nEnter seat#: ";
    cin>>seatNum;
    for(int i=0; i<10; i++)
    {
        for(int j=0; j<10; j++)
        {
            seatsThHo[i][j] = VACANT;
            seatsROG[i][j] = VACANT;
            seatsHoTr[i][j] = VACANT;
            }
        }
    switch(chosenMovie)
    {
        case 1:
            {
            cout<<"nYou wanted to buy ticket from the movie 'The Hobbit': ";
            cout<<"nYour row # is "<<rowNum<<" and you choosed seat # "<<seatNum;
                    seatsThHo[rowNum][seatNum] = RESERVED;
            }       
            break;
        case 2:
            {
            cout<<"nYou wanted to buy ticket from the movie 'Rise Of The Guardians': ";
            cout<<"nYour row # is "<<rowNum<<" and you choosed seat # "<<seatNum;
                    seatsROG[rowNum][seatNum] = RESERVED;
            }
            break;
        case 3:
            {
            cout<<"nYou wanted to buy ticket from the movie 'Hotel Transylvania': ";
            cout<<"nYour row # is "<<rowNum<<" and you choosed seat # "<<seatNum;
                    seatsHoTr[rowNum][seatNum] = RESERVED;
            }
            break;
        case 0:
            break;
        }
}
void Movies::availableSeats()
{
    switch(chosenMovie)
    {
        case 1:
            {
            cout<<"nAvailable Seats for the movie 'Rise Of The Guardians': ";
                    for(int x=0; x<10; x++)
                                {
                        for(int y=0; y<10; y++)
                                {
                                    cout<<seatsThHo[x][y]<<"  ";
                                }
                                }
            }       
            break;
        case 2:
            {
            cout<<"nAvailable Seats for the movie 'Rise Of The Guardians': ";
                    for(int x=0; x<10; x++)
                                {
                        for(int y=0; y<10; y++)
                                {
                                    cout<<seatsROG[x][y]<<"  ";
                                }
                                }
            }
            break;
        case 3:
            {
            cout<<"nAvailable Seats for the movie 'Hotel Transylvania': ";
                    for(int x=0; x<10; x++)
                                {
                        for(int y=0; y<10; y++)
                                {
                                    cout<<seatsHoTr[x][y]<<"  ";
                                }
                                }
            }
            break;
        case 0:
            break;
        }
}

错误:

[Linker error] main.o:main.cpp:(.text$_ZN7MachineC2Ev[Machine::Machine()]+0x8): undefined reference to `vtable for Machine'


[Linker error] main.o:main.cpp:(.text$_ZN7MachineC1Ev[Machine::Machine()]+0x8): undefined reference to `vtable for Machine' 

collect2: ld returned 1 e xit status


 C:UsersMary GraceDesktopTheater Reservation ProgramMakefile.win [Error] [TheaterProject.exe] Error 1 (if this is the only error: please check your library includes)

我真的不知道现在该做什么，我已经为这个项目工作了大约3个小时了

文件imp.cpp只是header.h的副本。源文件应该包含头文件中方法的实现。

void Machine::menu()
{
    // Code for this method
}

等。

你遇到的问题是因为你的类中没有构造函数或析构函数。包含虚函数的类还必须实现构造函数和(虚)析构函数。不需要包含任何内容，可以为空，只需要定义。

错误信息中有一个提示:

[Linker error] main.o:main.cpp:(.text$_ZN7MachineC2Ev[Machine::Machine()]+0x8): undefined reference to `vtable for Machine'
Here -------------------------------------------------^^^^^^^^^^^^^^^^

实现构造函数和析构函数，它应该可以工作。

由于构造函数和析构函数可以为空，我建议您将它们添加到头文件中的类定义中:

class Machine
    {
        public:
            Machine() {}  // Constructor with empty body
            virtual ~Machine() {}  // Empty virtual destructor
            // Rest of the class...
    };

对另一个类执行相同的操作，但当然要使用适当的名称。

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