Question

C++ problem with dynamic arrays is that once the array is created using the new operator the size cannot be changed. For example, you might want to add or delete entries from the array similar to the behavior of a vector. This project asks you to create a class called DynamicStringArray that includes member functions that allow it to emulate the behavior of a vector of strings.

The class should have:

• A private member variable called dynamicArray that references a dynamic array of type string.
• A private member variable called size that holds the number of entries in the array.
• A default constructor that sets the dynamic array to NULL ( or nullptr) and sets size to 0.
• A function that returns size.
• A function named addEntry that takes a string as input. The function should create a new dynamic array one element larger than dynamicArray, copy all elements from dynamicArray into the new array, add the new string onto the end of the new array, increment size, delete the old dynamicArray, and then set dynamicArray to the new array.
• A function named deleteEntry that takes a string as input. The function should search dynamicArray for the string. If not found, return false. If found, create a new dynamic array one element smaller than dynamicArray. Copy all elements except the input string into the new array, delete  dynamicArray, decrement size, and return true.
• A function named getEntry that takes an integer as input and returns the string at that index in dynamicArray. Return NULL if the index is out of dynamicArray’s bounds.
• A copy constructor that makes a copy of the input object’s dynamic array.
• Overload the assignment operator so that the dynamic array is properly copied to the target object.
• A destructor that frees up the memory allocated to the dynamic array.

Your program will be tested with the following driver program ( main function). Make sure you do not change the testing code in any way to prevent losing points.

int main()
{
DynamicStringArray names;

// List of names
names.addEntry("Frank");
names.addEntry("Wiggum");
names.addEntry("Nahasapeemapetilon");
names.addEntry("Quimby");
names.addEntry("Flanders");

// Output list
cout << "List of names:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

// Add and remove some names
names.addEntry("Spuckler");
cout << "After adding a name:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

names.deleteEntry("Nahasapeemapetilon");
cout << "After removing a name:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

names.deleteEntry("Skinner");
cout << "After removing a name that isn't on the list:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

names.addEntry("Muntz");
cout << "After adding another name:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

// Remove all of the names by repeatedly deleting the last one
while (names.getSize() > 0) {
names.deleteEntry(names.getEntry(names.getSize() - 1));
}

cout << "After removing all of the names:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

names.addEntry("Olivia");
cout << "After adding a name:" << endl;
for (int i = 0; i < names.getSize(); i++)
cout << names.getEntry(i) << endl;
cout << endl;

cout << "Testing copy constructor" << endl;
DynamicStringArray names2(names);
// Remove Olivia from names
names.deleteEntry("Olivia");
cout << "Copied names:" << endl;
for (int i = 0; i < names2.getSize(); i++)
cout << names2.getEntry(i) << endl;
cout << endl;

cout << "Testing assignment" << endl;
DynamicStringArray names3 = names2;
// Remove Olivia from names2
names2.deleteEntry("Olivia");
cout << "Copied names:" << endl;
for (int i = 0; i < names3.getSize(); i++)
cout << names3.getEntry(i) << endl;
cout << endl;

cout << "Enter a character to exit." << endl;
char wait;
cin >> wait;
return 0;
}

Answer 1

If you have any doubts, please give me comment...

#include<iostream>

using namespace std;

class DynamicStringArray{

    public:

        DynamicStringArray(){

            dynamicArray = NULL;

            size = 0;

        }

        int getSize(){

            return size;

        }

        void addEntry(string val){

            string *temp = new string[size+1];

            for(int i=0; i<size; i++){

                temp[i] = dynamicArray[i];

            }

            // delete dynamicArray;

            dynamicArray = temp;

            dynamicArray[size] = val;

            size++;

        }

        bool deleteEntry(string val){

            bool isFound = false;

            int pos=0;

            for(pos=0; pos<size; pos++){

                if(dynamicArray[pos]==val){

                    isFound = true;

                    break;

                }

            }

            if(!isFound)

                return false;

            string *temp = new string[size-1];

            for(int i=0, k=0; i<size; i++){

                if(i==pos){

                    continue;

                }

                temp[k] = dynamicArray[i];

                k++;

            }

            // delete dynamicArray;

            dynamicArray = temp;

            size--;

            return true;

        }

        string getEntry(int index){

            if(index<size)

                return dynamicArray[index];

            return NULL;

        }

        DynamicStringArray(const DynamicStringArray &c){

            dynamicArray = c.dynamicArray;

            size = c.size;

        }

        ~DynamicStringArray(){

            // delete dynamicArray;

        }

    private:

        string *dynamicArray;

        int size;

};

int main()

{

DynamicStringArray names;

// List of names

names.addEntry("Frank");

names.addEntry("Wiggum");

names.addEntry("Nahasapeemapetilon");

names.addEntry("Quimby");

names.addEntry("Flanders");

// Output list

cout << "List of names:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

// Add and remove some names

names.addEntry("Spuckler");

cout << "After adding a name:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

names.deleteEntry("Nahasapeemapetilon");

cout << "After removing a name:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

names.deleteEntry("Skinner");

cout << "After removing a name that isn't on the list:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

names.addEntry("Muntz");

cout << "After adding another name:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

// Remove all of the names by repeatedly deleting the last one

while (names.getSize() > 0) {

names.deleteEntry(names.getEntry(names.getSize() - 1));

}

cout << "After removing all of the names:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

names.addEntry("Olivia");

cout << "After adding a name:" << endl;

for (int i = 0; i < names.getSize(); i++)

cout << names.getEntry(i) << endl;

cout << endl;

cout << "Testing copy constructor" << endl;

DynamicStringArray names2(names);

// Remove Olivia from names

names.deleteEntry("Olivia");

cout << "Copied names:" << endl;

for (int i = 0; i < names2.getSize(); i++)

cout << names2.getEntry(i) << endl;

cout << endl;

cout << "Testing assignment" << endl;

DynamicStringArray names3 = names2;

// Remove Olivia from names2

names2.deleteEntry("Olivia");

cout << "Copied names:" << endl;

for (int i = 0; i < names3.getSize(); i++)

cout << names3.getEntry(i) << endl;

cout << endl;

cout << "Enter a character to exit." << endl;

char wait;

cin >> wait;

return 0;

}