Describe the changes to the previous stack implementation that are necessaryto replace the fixed-size array with a resizable array.

Question

What will be an ideal response?

Answer 1

In the header file for ArrayStack, change the declaration of items and declare a new data member maxItems:
```
ItemType* items = new ItemType[DEFAULT_CAPACITY]; // Array of stack items
int maxItems; // Max capacity of the stack

```
Also, change the name of MAX_STACK to DEFAULT_CAPACITY to reflect its change in meaning.
In the implementation file, add an initializer to the definition of the constructor that initializes maxItems to DEFAULT_CAPACITY. Thus, the constructor appears as follows:
```
template
ArrayStack::ArrayStack() : top(-1), maxItems(DEFAULT_CAPACITY)
{
} // end default constructor

```
Then change the definition of the pushmethod so that when the array—and hence the stack—becomes full, pushdoubles the capacity of the array instead of failing to add the data item and returning false. Since the stack is never full, the following version of the pushmethod alwaysreturns true:
```
template
boolArrayBag::add(const ItemType& newEntry)
{
bool hasRoomToAdd = (itemCount < maxItems);
if (!hasRoomToAdd)
{
ItemType* oldArray = items;
items = newItemType[2 * maxItems];
for (int index = 0; index < maxItems; index++)
items[index] = oldArray[index];
delete [ ] oldArray;
maxItems = 2 * maxItems;
} // end if
// We can always add the item
items[itemCount] = newEntry;
itemCount++;
return true;
} // end push

```