// Stack of integers implemented with private inheritance
//  There is no error checking and in particular the stack
//  is limited to a fixed size. A GrowableArray would be better.

#include "Array.h"

class IntStack : private Array {
public:
    // Make the length available - it is the maximum stack depth
    using Array::length;

    IntStack() : Array(20), top(0) { }

    // Stack interface is push and pop - each use the inherited
    // overloaded array operator, but we show two different ways
    // to access it
    void push(int v) { operator[](top++) = v; }
    int pop() { return (*this)[--top]; }

    bool empty() const { return top == 0; }

private:
    int top;
};