How to change my stack into a queue?

[dxfoo]

Without using templates, how can I convert my stack class into a queue class? I can't find anything on the web.

class Stack
{
private:
	int stack[100];
	int top;
public:
	Stack(): top(0) { }
	~Stack() {}

	void push(int x)
	{
		if (top < 100)
			stack[top++] = x; 
	}

	int pop()
	{
		if (top > 0) 
			return stack[--top];
		else
			return 0;
	}

	void clear() { top = 0; }
	int getSize() { return top; }
	int isEmpty() { return top == -1; }
	int isFull() { return top == 100; }
};