// stack.h
const int MAX_SIZE= 20;
class FullStack                         //Exception class thrown by Push when stack is full.
{};

class EmptyStack                        //Exception class thrown by Pop and Top when stack is empty.
{};


class StackType

{
    public:
        StackType();                     // Class constructor
        void Clear();                    // Clear the stack contents
        bool IsFull() const;             // Determines whether the stack is full
        bool IsEmpty() const;            // Determines whether the stack is empty
        void Push(char item);            // Adds an item to the top of the stack.
        char Pop();                      // Removes and returns the top item from the stack
        char Top();                      // Returns a copy of top item on the stack.
        void Print();                    // Prints contents of stack to screen from top to bottom


    private:
        char   items[MAX_SIZE];          //array
        int    top;                      // Top of stack . array subscript value or -1


};



// stack.cpp




StackType::StackType()

{
    top = -1;
}


bool StackType::IsEmpty() const
{
    return (top == -1);
}

bool StackType::IsFull() const
{
    return (top == MAX_SIZE-1);
}


void StackType::Push(char newItem)
{
    if (IsFull())
        throw FullStack();
    top++;
    items[top] = newItem;
}



char StackType::Pop()

{
    if(IsEmpty())
        throw EmptyStack();
    top--;
    return items[top];
}