Stack堆栈是频繁使用FILO数据结构，FILO指first in last out，最后出来。

因为只有一个堆叠端口，这也是在口腔进入口。

可以在堆栈中只能操作，你不能访问其它元件的堆叠。器。

Stack的实现是依赖其它容器的。用deque做底层数据结构。这种实现。在STL中往往不称做container容器，往往被归类为container adapter容器适配器。deque是双向开口的数据结构，功能远强大于栈，仅仅需简单分装就可以做成栈。

用其它容器做底层数据结构也但是实现栈，vector、list也支持empty、size、back、push_back、pop_back操作。我想用deque是一种折中吧！假设用vector在又一次分配空间时须要拷贝原来空间的元素。释放原来空间。假设使用list的话。每一次push_back、pop_back都涉及空间的分配和释放。

G++ 2.91.57，cygnus\cygwin-b20\include\g++\stl_stack.h 完整列表

/*

 *

 * Copyright (c) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996,1997

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */

/* NOTE: This is an internal header file, included by other STL headers.

 *   You should not attempt to use it directly.

 */

#ifndef __SGI_STL_INTERNAL_STACK_H

#define __SGI_STL_INTERNAL_STACK_H

__STL_BEGIN_NAMESPACE

#ifndef __STL_LIMITED_DEFAULT_TEMPLATES

template <class T, class Sequence = deque<T> >

#else

template <class T, class Sequence>

#endif

class stack {

	//友元函数，后面会展开的

  friend bool operator== __STL_NULL_TMPL_ARGS (const stack&, const stack&);

  friend bool operator< __STL_NULL_TMPL_ARGS (const stack&, const stack&);

public:

  typedef typename Sequence::value_type value_type;

  typedef typename Sequence::size_type size_type;

  typedef typename Sequence::reference reference;

  typedef typename Sequence::const_reference const_reference;

protected:

  Sequence c;	// 底层容器deque

public:

  // 下面全然利用 Sequence c 的操作，完毕 stack 的操作。

  bool empty() const { return c.empty(); }

  size_type size() const { return c.size(); }

  reference top() { return c.back(); }

  const_reference top() const { return c.back(); }

  void push(const value_type& x) { c.push_back(x); }

  void pop() { c.pop_back(); }

};

template <class T, class Sequence>

bool operator==(const stack<T, Sequence>& x, const stack<T, Sequence>& y) {

  return x.c == y.c;

}

template <class T, class Sequence>

bool operator<(const stack<T, Sequence>& x, const stack<T, Sequence>& y) {

  return x.c < y.c;

}

__STL_END_NAMESPACE

#endif /* __SGI_STL_INTERNAL_STACK_H */

// Local Variables:

// mode:C++

// End: