Определить базовый класс и на его основе производные классы

#ifndef _STUDENT_H_
#define _STUDENT_H_
 
#include <string>
#include <vector>
#include <iostream>
 
using namespace std;
 
class student{
protected:
    string m_name;
    int m_year_of_admission;
    short m_course;
    short m_group_number;
    short m_pay;
    vector <float> marks;//collection of marks
    float aver_mark;//average mark 
public:
    student (string name, int year_of_admission, short course, short group_number, short pay);
    virtual ~student();
    virtual void show();
    friend void GPA(student *st[]);// average mark
};
 
class social : public student{
    string m_social_work;
    float m_percent;
public:
    social(string name, int year_of_admission, short course, short group_number, short pay,
        string social_work, float percent);
    ~social();
    virtual void show();
};
 
class sport : public student{
    string m_kind_of_sport;
public:
    sport(string name, int year_of_admission, short course, short group_number, short pay, string kind_of_sport);
    ~sport();
    virtual void show();
};
 
#endif//end of _STUDENT_H_

#include "student.h"
 
extern int students = 3;
 
student::student(string name, int year_of_admission, short course, short group_number, short pay):
    m_name(name), m_year_of_admission(year_of_admission), m_course(course), m_group_number(group_number), m_pay(pay){
    cout<<"Would you like to add marks for "<<m_name<<"? (1 for Yes, 0 for No)"<<endl;
    bool answer = false;
    cin>>answer;
    if (answer == true){
        do{
            answer = false;
            float mark;
            cout<<"Enter mark"<<endl;
            cin>>mark;
            marks.push_back(mark);
            cout<<"Add a new ? (1 for Yes, 0 for No)"<<endl;
            cin>>answer;
        }
        while (answer == true);
    }//if end
    aver_mark = 0;
}
 
student::~student(){
}
 
void student::show(){
    cout<<"Student name: "<<m_name<<endl
        <<"year of admission: "<<m_year_of_admission<<endl
        <<"course: "<<m_course<<endl
        <<"group number: "<<m_group_number<<endl
        <<"scollarship: "<<m_pay<<endl
        <<"AV MARK: "<<aver_mark<<endl;
}
 
social::social(string name, int year_of_admission, short course, short group_number, short pay, 
               string social_work, float percent) : 
               student(name, year_of_admission, course, group_number, pay){
    m_social_work = social_work;
    m_percent = percent;
}
 
social::~social(){
}
 
void social::show(){
        student::show();
        cout<<"social work: "<<m_social_work<<endl
        <<"%: "<<m_percent<<endl;
}
 
sport::sport(string name, int year_of_admission, short course, short group_number, short pay, string kind_of_sport):
        student(name, year_of_admission, course, group_number, pay){
    m_kind_of_sport = kind_of_sport;
}
 
sport::~sport(){
}
 
void sport::show(){
    student::show();
    cout<<"sport: "<<m_kind_of_sport<<endl;
}
 
void GPA (student *st[]){//count averege mark of all stud, and out name of stud which have max mark 
    float sum = 0;
 
    if (students == 0){
        cerr<<"Error: no students"<<endl;
        return;
    }
 
    for(int i = 0; i < students; i++){
        if (st[i]->marks.size() > 0){
            for(int j = 0; j < st[i]->marks.size(); j++){ 
                sum += st[i]->marks[j];
            }
            st[i]->aver_mark = sum / st[i]->marks.size();
            sum = 0;//set sum to zero
        }//if end
    }//end of stud block
 
    float max = st[0]->aver_mark;
    for (int i = 1; i < students; i++){
        if (st[i]->aver_mark > st[i-1]->aver_mark) 
            max = st[i]->aver_mark;
    }
    cout<<"MAX mark !!!!!!!!"<<max<<endl;
    for (int i = 0; i<students; i++)
        if(st[i]->aver_mark == max)
            cout<<st[i]->m_name<<" have the most high averge mark "<<st[i]->aver_mark<<endl;
}

#include "student.h"
 
const int students = 3;//number of students
 
int main(){
    student *coll[students];
    coll[0] = new student("standart student", 2010, 3, 306, 500);
    coll[1] = new social("social student", 2011, 2, 202, 600, "shop steward", 10.0);
    coll[2] = new sport("sport student", 2009, 4, 401, 650, "boxing");
    for(int i = 0; i<students; i++)
        coll[i]->show();
    GPA(coll);
    system("pause");
    return 0;
}

delete [] coll;

delete coll[0];
delete coll[1];
delete coll[2];