Virutal base pointer sort question

[Teelnaw]

I am trying to sort using base pointers to an array of derived objects. My issue is the sort needs to access a function for each derived class that calculates area of which ever derived object it is sorting through. How can I swap a value that is part of a function and not a member variable of the derived class? I created a setArea function but, the compiler doesn't like it,nor do I think it would work. Here is was I have so far, any help would be greatly appreciated.

Thanks

void Shape::sortShape (Shape* array, int numShapes)
{


    for (int i = numShapes; i >= 1; i--)
    {

        for(int itr = 0; itr != itr + i; ++itr)
        {

            if (itr > itr + 1)
            {
                   double temp;
                  temp = array[itr].getArea();
                  array[itr].setArea(array[itr+1].getArea());
                  array[itr+1].setArea(temp);
            }


        }
    }
  


}

set Function

float Rectangle::setArea(float area)
{

    float a = getArea();
    return a;

}

[LB]

You should read up on the Clone Pattern, which allows you to clone a derived type not knowing what the type actually is.
http://www.cplusplus.com/articles/NTA0RXSz/

[ne555]

Your set Function does not set anything.

I am trying to sort using base pointers to an array of derived objects.

In that case you need to provide a comparator function

bool cmp( const base *A, const base *B){
  return A->area() < B->area(); //using polymorphism
}

How can I swap a value that is part of a function and not a member variable of the derived class?

¿eh? you will be swapping the pointers

[Teelnaw]

Update... just realized that I should be swapping the objects/pointers not the area. This avoids the use of a set function.

void Shape::sortShape (Shape* array[], int numShapes)
{


    for (int i = numShapes; i >= 1; i--)
    {

        for(int itr = 0; itr != itr + i; ++itr)
        {

            if (array[itr]->getArea() < array[itr + i]->getArea())
            {
                Shape* temp;
                temp = array[itr];
                array[itr] = array[itr+1];
                array[itr+1] = temp;
            }


        }
    }