changing an array class to dynamic array class

[ephekt]

everything i have read says this should be easy and that you just add

  typedef double* DoublePtr;
  DoublePtr p;
  p = new double [10]

but where do i add this code?

#include<iostream>
using namespace std;
const int MAX_SIZE = 50;

class ListDynamic
{
	
    public:
        
        ListDynamic();
        bool full();
        int getSize();
        void addValue(double value);
        double getValue(int index);
        double getLast();
        void deleteLast();
        friend ostream& operator <<(ostream& out, const ListDynamic& thisList);  
    
    private:
        double listValues[MAX_SIZE];
        int size;
};
int main()
{
    double value;
    ListDynamic l;
    cout << "size of List " << l.getSize() << endl;
     
     
     
    cout << "New size of List " << l.getSize() << endl;
    cout << "First Value: " << l.getValue(0) << endl;
    cout << "Last Value: " << l.getLast() << endl;
    cout << "deleting last value from list" << endl;
    l.deleteLast();
    cout << "new list size "  << l.getSize() << endl;
    cout << "the list now contains: " << endl << l << endl;
    system("pause");
    return 0;
}

ListDynamic::ListDynamic()
{
    size = 0;
}

bool ListDynamic::full()
{
    return (size == MAX_SIZE);
}

int ListDynamic::getSize()
{
    return size;
}

void ListDynamic::addValue(double value)
{
    if (size < MAX_SIZE)
    {
        listValues[size] = value;
        size++;
    }
    else
        cout << "\n\n*** Error in ListDynamic Class: Attempting to add value past max limit.";
}

double ListDynamic::getValue(int index)
{
    if (index < size)
        return listValues[index];
    else
        cout << "\n\n*** Error in ListDynamic Class: Attempting to retrieve value past current size.";
}
double ListDynamic::getLast()
{
    if (size > 0)
        return getValue(size - 1);
    else
        cout << "\n\n*** Error in ListDynamic Class: Call to getLast in Empty List.";
}

void ListDynamic::deleteLast()
{
    if (size > 0)
        size--;
    else
        cout << "\n\n*** Error in ListDynamic Class: Call to deleteLast in Empty List.";
}
ostream& operator <<(ostream& out, const ListDynamic& thisList)
{
    for (int i = 0; i < thisList.size; i++)
        out << thisList.listValues[i] << endl;
    return out;
}  

[ephekt]

anyone? I could really use some help with this?

[LB]

Does it have to be a dynamic array? Could you use std::vector instead?

[ephekt]

Thank you for responding, Sadly it has to be a dynamic array, I am a little closer (I think) I have the dynamic array declared in my program but I cant use it. I tried manipulating the dynamic array with .notation but it didn't work. Is something wrong with my pointer, or is my syntax just wrong?

#include<iostream>
using namespace std;
const int MAX_SIZE = 50;
typedef double* DoublePtr;
  
class ListDynamic
{
	
    public:
        
        ListDynamic();
        bool full();
        int getSize();
        void addValue(double value);
        double getValue(int index);
        double getLast();
        void deleteLast();
        friend ostream& operator <<(ostream& out, const ListDynamic& thisList);  
    
    private:
        double* listValues;
        int size;
};
int main()
{
    double value;
    DoublePtr p;
    p = new double [50];
    ListDynamic l;
    cout << "size of List " << l.getSize() << endl;
    cout << "enter value to add to list: ";
    cin >> value;
    l.addValue(value);
    cout << "enter value to add to list: ";
    cin >> value;
    l.addValue(value);
    cout << "enter value to add to list: ";
    cin >> value;
    l.addValue(value);
    cout << "enter value to add to list: ";
    cin >> value;
    l.addValue(value);
    cout << "enter value to add to list: ";
    cin >> value;
    l.addValue(value);
    cout << "New size of List " << l.getSize() << endl;
    cout << "First Value: " << l.getValue(0) << endl;
    cout << "Last Value: " << l.getLast() << endl;
    cout << "deleting last value from list" << endl;
    l.deleteLast();
    cout << "new list size "  << l.getSize() << endl;
    cout << "the list now contains: " << endl << l << endl;
    delete [] p;
    system("pause");
    return 0;
}

ListDynamic::ListDynamic()
{
    size = 0;
}

bool ListDynamic::full()
{
    return (size == MAX_SIZE);
}

int ListDynamic::getSize()
{
    return size;
}

void ListDynamic::addValue(double value)
{
    if (full())
    {
        double* temp = new double[size];
        std::copy(listValues, listValues + size, temp);

        delete[] listValues;
        listValues = new double[size + 1];

        std::copy(temp, temp + size, listValues);
        listValues[size] = value;
        delete[] temp;
    } else
    {
        listValues[size++] = value;
    }
}
double ListDynamic::getValue(int index)
{
    if (index < size)
        return listValues[index];
    else
        cout << "\n\n*** Error in List Class: Attempting to retrieve value past current size.";
}
double ListDynamic::getLast()
{
    if (size > 0)
        return getValue(size - 1);
    else
        cout << "\n\n*** Error in List Class: Call to getLast in Empty List.";
}

void ListDynamic::deleteLast()
{
    if (size > 0)
        size--;
    else
        cout << "\n\n*** Error in List Class: Call to deleteLast in Empty List.";
}
ostream& operator <<(ostream& out, const ListDynamic& thisList)
{
    for (int i = 0; i < thisList.size; i++)
        out << thisList.listValues[i] << endl;
    return out;
}  

[LB]

It would be helpful if you copied and pasted the exact compilation errors you are getting.

[ephekt]

Im not getting any errors from this code it compiles and runs just fine. my problem is how do i use my pointer variable p which is supposed to point to my array object l. Right now the pointer is not being used and the class object is doing everything.

[LB]

Let me get this straight: you want to go from a modular design to a brittle design? Why?

[norm b]

Don't you get a segfault?

Hint: listValues needs to point to something.

[ephekt]

that was the assignment take the list class and make it a dynamic list class that uses a dynamic array instead an array of max size 50

[LB]

You misunderstand the assignment.

[ephekt]

We already did Project 11 in Homework 9. For this assignment, re-write that project using dynamic allocation. Call the updated class ListDynamic. This new class can always accept more values by dynamically allocating a new internal array when the current internal array is full.

What do you think its asking then?