#ifndef EXMAPLE18_STACK_H
#define EXMAPLE18_STACK_H

typedef void* T;

class Stack {
private:
    int top;
    T* impl;  // an array of pointers to void
public:
    Stack(int n=5) : top(-1), impl(new T[n]) {
    }
    ~Stack() {
        delete[] impl;
    }
    bool empty() const {
        return top == -1;
    }
    void push(T el) {
        impl[++top] = el;
    }
    T pop() {
        return impl[top--];
    }
};

#endif //EXMAPLE18_STACK_H