Question

template <class T>
class Stack
{
public:
/** clear
* Method to clear out or empty any items on stack,
* put stack back to empty state.
* Postcondition: Stack is empty.
*/
virtual void clear() = 0;

/** isEmpty
* Function to determine whether the stack is empty. Needed
* because it is undefined to pop from empty stack. This
* function will not change the state of the stack (const).
*
* @returns bool true if stack is empty, false otherwise.
*/
virtual bool isEmpty() const = 0;

/** push
* Add a new item onto top of stack.
*
* @param newItem The item of template type T to push on top of
* the current stack.
*/
virtual void push(const T& newItem) = 0;

/** top
* Return the top item from the stack. Note in this ADT, peeking
* at the top item does not remove the top item. Some ADT combine
* top() and pop() as one operation. It is undefined to try and
* peek at the top item of an empty stack. Derived classes should
* throw an exception if this is attempted.
*
* @returns T Returns the top item from stack.
*/
virtual T top() const = 0;

/** pop
* Remove the item from the top of the stack. It is undefined what
* it means to try and pop from an empty stack. Derived classes should
* throw an exception if pop() from empty is attempted.
*/
virtual void pop() = 0;

/** size
* Accessor method to provide the current size of the stack.
*
* @returns int The current size (number of items) on the stack.
*/
virtual int size() const = 0;

};

Given a stack of strings

Stack s;

Remove all of the items from the stack until you find that the top item is "stop", or until the stack is empty. For example, if you are given the stack

Top
---
horse
giraffe
zebra
stop
elephant
tiger
------
Bottom

Then after running your code the stack should have the following contents

Top
---
stop
elephant
tiger
------
Bottom

and don't forget to handle the case where there is no stop and thus the stack becomes empty.

Answer 1

Stack s;
while(!s.isEmpty())//runs upto stack is not empty
{
   if(s.top()=="stop")//if stop reached
   break;//then stopping
   s.pop();//poping until stop is found or stack is empty
}