STL源码剖析（二）---向量分析

    template <class _Tp, class _Alloc = __STL_DEFAULT_ALLOCATOR(_Tp) >
    class vector : protected _Vector_base<_Tp, _Alloc> 
    {
    private:
      typedef _Vector_base<_Tp, _Alloc> _Base;
    public:
      typedef _Tp value_type;
      typedef value_type* pointer;
      typedef const value_type* const_pointer;
      typedef value_type* iterator; //迭代器
      typedef const value_type* const_iterator;
      typedef value_type& reference;
      typedef const value_type& const_reference;
      typedef size_t size_type;
      typedef pt