Program is to store marks and name, roll no in a file:

class stud

  {

    int rno;

    char name[20];

    int m1,m2,m3;

    public:

                void accept()

                                {

                                cout<<"enter the roll no. : ";

                                cin>>rno;

                                cout<<"enter the name : ";

                                gets(name);

                                cout<<"enter marks of 3 subjects : ";

                                cin>>m1>>m2>>m3;

                                }

    };

     void main()

     {

     clrscr();

     stud s;

     s.accept();

     ofstream a ("stud.dat" , ios::binary | ios::app);

     a.write ( (char *) &s , sizeof(s) );

     a.close();

     }