Rắc rối với hàm ảo ?

[fire_dragon14988]

/*Đề bài: Thiết kế chương trình viêc nhập xuất ấn phẩm sau trong một nhà sách: băng, sách. Các thành phần dữ liệu của các ấn phẩm:
- Băng: tựa đề, giá, thời gian, số lượng
- Sách: tựa đề, giá, số trang, số lượng.
*/

#include <conio.h>#include <ctype.h>#include <iostream.h>#include <stdio.h>class PUBLICATION   //declare abstract class{    char Title[30];   protected:    float Price;    int Qty;   public:    PUBLICATION()        {            cout <<"Ten an pham: "; fflush(stdin);  gets(Title);            cout <<"\nDon gia: ";   cin >>Price;            cout <<"\nSo luong: ";  cin >>Qty;        }    void Put()        {            cout <<"\nAn pham " <<Title;            cout <<"\nCo don gia: " <<Price <<endl;            cout <<"\nSo luong: " <<Qty;        }        virtual void PutData() = 0;  // pure virtual function    virtual int IsOver() = 0;    virtual float Get_TG() = 0;}; class BOOK: public PUBLICATION{    int Page;    static float TTG_SACH;   public:    BOOK()        {            cout <<"\nSo trang: ";  cin >>Page;            TTG_SACH += PUBLICATION:: Qty * PUBLICATION:: Price;        }    virtual void PutData()        {            Put();            cout <<"\nSo trang: " <<Page <<endl;        }    int IsOver()        {            return TTG_SACH;        }};float BOOK:: TTG_SACH = 0; class TAPE: public PUBLICATION{    int PlayTime;    static float TTG_BANG;   public:    TAPE()        {            cout <<"\nThoi gian chay: ";    cin >>PlayTime;            TTG_BANG += Qty * Price;        }    void PutData()        {            Put();            cout <<"\nThoi gian chay: " <<PlayTime <<endl;        }    int IsOver()        {            return PlayTime > 90 ? 1 : 0;        }    virtual float Get_TG()        {            return TTG_BANG;        }};float TAPE:: TTG_BANG = 0; void main(){    int n1, n2;    clrscr();    cout <<"\nSo dau sach cua hang: ";  cin >>n1;    cout <<"\nSo dau bang trong cua hang: ";    cin >>n2;    BOOK *SACH;    TAPE *BANG;    PUBLICATION *DS[100];    //nhap du lieu    for(int i=0; i<n1; i++)        {            SACH = new BOOK;  //Lỗi            DS[i] = SACH;        }    for(i=0; i<n2; i++)        {            BANG = new TAPE;  //Lỗi(?) (?) [SIZE="4"][FONT="Arial"][COLOR="Black"][FIXED][FIXED][/FIXED][/FIXED][/COLOR][/FONT][/SIZE]            DS[i+n1] = BANG;        }    //xuat du lieu    for(i=0; i,n1; i++)        {            DS[i]->PutData();            cout <<(DS[i]->IsOver() == 1 ? " Sach hon 900 trang" : "") <<endl;        }    cout <<endl <<"Tong tri gia sach= " <<SACH->Get_TG() <<endl;    for(i=0; i<n2; i++)        {            DS[i+n1]->PutData();            cout <<(DS[i+n1]->IsOver() == 1 ? " Bang > 90" : "") <<endl;        }    cout <<endl <<"Tong tri gia bang= " <<BANG->Get_TG() <<endl;    getch();}[CODE]

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chú ý đặt code vào tag

[zkday2686]

Đã hết lỗi nhưng mình chưa test là đã chạy đúng với yêu cầu hay chưa.

 #include <conio.h>#include <ctype.h>#include <iostream.h>#include <stdio.h> class PUBLICATION   //declare abstract class{    char Title[30];   protected:    float Price;    int Qty;   public:        PUBLICATION()        {            cout <<"Ten an pham: "; fflush(stdin);  gets(Title);            cout <<"\nDon gia: ";   cin >>Price;            cout <<"\nSo luong: ";  cin >>Qty;        }    void Put()        {            cout <<"\nAn pham " <<Title;            cout <<"\nCo don gia: " <<Price <<endl;            cout <<"\nSo luong: " <<Qty;        }        virtual void PutData()=0;  // pure virtual function    virtual float IsOver() = 0;    virtual float Get_TG() = 0;    virtual ~PUBLICATION(){;};}; class BOOK: public PUBLICATION{    int Page;    static float TTG_SACH; public:    BOOK()        {            cout <<"\nSo trang: ";            cin >>Page;            TTG_SACH += (Qty * Price);        }     void PutData()        {            Put();            cout <<"\nSo trang: " <<Page <<endl;        }//thêm hàm này vào là ok    float Get_TG()    {        return 0.0;    }    float IsOver() // khai bao kieu float ma tra ve kieu int        {            return TTG_SACH;        }    virtual ~BOOK(){;};}; float BOOK:: TTG_SACH = 0; class TAPE: public PUBLICATION{    int PlayTime;    static float TTG_BANG;   public:    TAPE()        {            cout <<"\nThoi gian chay: ";    cin >>PlayTime;            TTG_BANG += Qty * Price;        }    void PutData()        {            Put();            cout <<"\nThoi gian chay: " <<PlayTime <<endl;        }    float IsOver()        {            return PlayTime > 90 ? 1.0 : 0.0;        }    float Get_TG()        {            return TTG_BANG;        }};float TAPE:: TTG_BANG = 0; void main(){    int n1, n2;//    clrscr();    cout <<"\nSo dau sach cua hang: ";  cin >>n1;    cout <<"\nSo dau bang trong cua hang: ";    cin >>n2;      BOOK* SACH;    TAPE* BANG;    PUBLICATION *DS[100];    //nhap du lieu    for(int i=0; i<n1; i++)        {            SACH = new BOOK;  //Lo^~i                           DS[i] = SACH;        }    for(i=0; i<n2; i++)        {            BANG = new TAPE;  //Lo^~i(?) (?) [size="4"][font="Arial"][color="Black"][fixed][fixed][/fixed][/fixed][/color][/font][/size]            DS[i+n1] = BANG;        }    //xuat du lieu    for(i=0; i,n1; i++)        {            DS[i]->PutData();            cout <<(DS[i]->IsOver() == 1 ? " Sach hon 900 trang" : "") <<endl;        }    cout <<endl <<"Tong tri gia sach= " <<SACH->Get_TG() <<endl;    for(i=0; i<n2; i++)        {            DS[i+n1]->PutData();            cout <<(DS[i+n1]->IsOver() == 1 ? " Bang > 90" : "") <<endl;        }    cout <<endl <<"Tong tri gia bang= " <<BANG->Get_TG() <<endl;    getch();}

bạn test lại xem sao nhé. mình chạy được trên VC++6.0 rồi..