has-a的关系，没有复制构造函数，这么初始化可以么StackSeq::StackSeq (IStack const & stack )

#if !defined (STACK_H)

#define STACK_H

// (c) Bartosz Milewski 2000



const int maxStack = 16;



class IStack

{

	friend class StackSeq; // give it access to private members

public:

	IStack (): _top (0) {}

	void Push (int i);

	int  Pop ();

private:

	int _arr [maxStack];

	int _top;

};



class StackSeq

{

public:

	StackSeq (IStack const & stack);

	bool AtEnd () const;   // are we done yet?

	void Advance ();       // move to next item

	int GetNum ()const;    // retrieve current item

private:

	IStack const & _stack; // reference to stack

	int	           _iCur;  // current index into stack

};



#endif



StackSeq::StackSeq (IStack const & stack )

	: _iCur (0), _stack (stack) // init reference

{}