1.insert_iterator

这个adapter将iterator的赋值（assign）操作变为安插（insert操作），并将iterator右移一个位置。如此便可让user连续执行[表面上assign而实际上insert]的行为。

template <class _Container> class insert_iterator { protected:   _Container* container ; //底层容器   typename _Container::iterator iter; public:   typedef _Container          container_type;   typedef output_iterator_tag iterator_category; //注意类型   typedef void                value_type;   typedef void                difference_type;   typedef void                pointer;   typedef void                reference;   insert_iterator(_Container& __x, typename _Container::iterator __i)     : container (&__x), iter (__i) {}   insert_iterator<_Container>&   operator=(const typename _Container::value_type& __value) {     iter = container-> insert(iter, __value);  //关键：转调用insert()     ++ iter;  //令insert_iterator永远跟随其target贴身移动     return *this;   }   insert_iterator<_Container>& operator*() { return *this; }   insert_iterator<_Container>& operator++() { return *this; }   insert_iterator<_Container>& operator++(int) { return *this; }

};

2.inserter

辅助函式，帮助user使用inserter_iterator

template <class _Container, class _Iterator> inline insert_iterator<_Container> inserter(_Container&__x, _Iterator__i) {   typedef typename _Container::iterator __iter;   return insert_iterator<_Container>(__x, __iter(__i)); }

3.copy

template<class InputIterator,

             class OutputIterator>

OutputIterator

          copy(InputIterator first,InputIterator last,OutputIterator result)

{

              while(first != last) {

                      *result = *first;

                      ++result ; ++first;

               }

               return result;

}

4.示例

http://www.cplusplus.com/reference/iterator/inserter/

// inserter example #include <iostream> // std::cout #include <iterator> // std::front_inserter #include <list> // std::list #include <algorithm> // std::copy int main () { std::list<int> foo,bar; for (int i=1; i<=5; i++) { foo.push_back(i); bar.push_back(i*10); } std::list<int>::iterator it = foo.begin(); advance (it,3); std::cout << "foo contains:"; for ( std::list<int>::iterator it = foo.begin(); it!= foo.end(); ++it ) std::cout << ' ' << *it; std::cout << '\n'; std::cout << "bar contains:"; for ( std::list<int>::iterator it = bar.begin(); it!= bar.end(); ++it ) std::cout << ' ' << *it; std::cout << '\n'; std::copy (bar.begin(),bar.end(),std::inserter(foo,it)); std::cout << "foo contains:"; for ( std::list<int>::iterator it = foo.begin(); it!= foo.end(); ++it ) std::cout << ' ' << *it; std::cout << '\n'; return 0; } 执行结果：