I need help with "Inheritance" and "Polymorphism"

From:

"Fao" <spharris55@yahoo.com>

Newsgroups:

comp.lang.c++

Date:

27 Apr 2006 10:51:30 -0700

Message-ID:

<1146160290.216173.300880@j33g2000cwa.googlegroups.com>

Hello, I am having some problems with inheritance. The compiler does
not not return any error messages, but when I execute the program, it
only allows me to enter the number, but nothing else happend. I think
the problem may be in my input function or in the main function.

If anyone out there can help me it woul be greatly appreciated.

Here is the code:

#include <iostream>
using namespace std;

const int SENTINEL = -999;

class SumType
{
protected:
    int n[10];
    int sum, max, max2, avg;
    int counter;
    int number;
    int *ptr0, *ptr1, *ptr;
public:
    SumType();
    void input();
    void calculation();
    double output();
};

class AverageType: public SumType
{
protected:
    double avg;
public:
    void calculation();
    double output();
};

class MaxType: public SumType
{
protected:
    double max, max2;
public:
    void calculation();
    double output();
};

class Max2Type: public SumType
{
protected:
    double max2;
public:
    void calculation();
    double output();
};

///////////////////////////////////////////////////////////////////////////////////

SumType::SumType()
{
    sum = 0;
    max = 0;
    max2 = 0;
    avg = 0;
    counter = 0;
    number = 0;
}

void SumType::input()
{
    cout << "Enter your numbers: " << endl;
    //ptr0 = &n[0];
    while(number != SENTINEL)
    {
        counter++;
        cin >> counter;
    }
}

void SumType::calculation()
{
    sum = sum + number;

}

double SumType::output()
{
    return sum;

}

//////////////////////////////////////////////////////////////////////////////////////

void AverageType::calculation()
{
    avg = sum / counter;
}

double AverageType::output()
{
    return avg;
}

////////////////////////////////////////////////////////////////////////////////////

void MaxType::calculation()
{
    int i;

    cin >> n[0] >> n[1];

    if (n[0] > n[1])
    {
        max = n[0];
        max2 =n[1];
    }

    else
    {
        max = n[1];
        max2 = n[0];
    }

    i = 2;
    cin >> n[i];

    while (n[i] != -999)
    {
        if (n[i] > max)
        {
            max2 = max;
            max = n[i];
        }

        if (n[i] < max &&n[i] > max2)
        {
            max2 = n[i];
        }

        if (n[i] < max2)
        { }

        i++;
        cin >> n[i];
    }
}

double MaxType::output()
{
    return max;
}

//////////////////////////////////////////////////////////////////////////

void Max2Type::calculation()
{
    int i;

    cin >> n[0] >> n[1];

    if (n[0] > n[1])
    {
        max = n[0];
        max2 =n[1];
    }

    else
    {
        max = n[1];
        max2 = n[0];
    }

    i = 2;
    cin >> n[i];

    while (n[i] != -999)
    {
        if (n[i] > max)
        {
            max2 = max;
            max = n[i];
        }

        if (n[i] , max &&n[i] > max2)
        {
            max2 = n[i];
        }

        if (n[i] < max2)
        { }

        i++;
        cin >> n[i];
    }
}

double Max2Type::output()
{
    return max2;
}

/////////////////////////////////////////////////////////////////

int main()
{
    SumType s1;
    AverageType a1;
    MaxType m1;
    MaxType m2;

    s1.input();
    s1.calculation();
    s1.output();

    a1.input();
    a1.calculation();
    a1.output();

    m1.input();
    m1.calculation();
    m1.output();

    m2.input();
    m2.calculation();
    m2.output();

    cout << "The sum is "<< s1.output()<<endl;
    cout << "The average is " << a1.output() << endl;
    cout << "The largest number is "<< m1.output() <<endl ;
    cout << "The second largest number is "<< m2.output() <<endl;
    cout << endl << endl;

    return 0;
}

/*
OUTPUT:

*/