STL中的iterator adapter

最新推荐文章于 2024-11-05 15:58:53 发布

alexmahone_xie

最新推荐文章于 2024-11-05 15:58:53 发布

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分类专栏： c&amp;amp;c++那些事儿文章标签： iterator output stream class insert basic

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以ostream_iterator 来说，下面是从vc++摘取的

:template<class _Ty, class _Elem = char, class _Traits = char_traits<_Elem> > class ostream_iterator : public _Outit { // wrap _Ty inserts to output stream as output iterator public: typedef _Elem char_type; typedef _Traits traits_type; typedef basic_ostream<_Elem, _Traits> ostream_type; ostream_iterator(ostream_type& _Ostr, const _Elem *_Delim = 0) : _Myostr(&_Ostr), _Mydelim(_Delim) { // construct from output stream and delimiter } ostream_iterator<_Ty, _Elem, _Traits>& operator=(const _Ty& _Val) { // insert value into output stream, followed by delimiter *_Myostr << _Val; if (_Mydelim != 0) *_Myostr << _Mydelim; return (*this); } ostream_iterator<_Ty, _Elem, _Traits>& operator*() { // pretend to return designated value return (*this); } ostream_iterator<_Ty, _Elem, _Traits>& operator++() { // pretend to preincrement return (*this); } ostream_iterator<_Ty, _Elem, _Traits> operator++(int) { // pretend to postincrement return (*this); } protected: const _Elem *_Mydelim; // pointer to delimiter string (NB: not freed) ostream_type *_Myostr; // pointer to output stream };

deque<int> id(ia, ia + 6);

copy(id.begin(), id.end(), ostream_iterator<int>(cout, " "));

原型：copy(first, last, result)

(在copy中，有*result= *first;---->ostream_iterator::operator=()--->相当于在输出流中插入一个字符

而result++等都是空操作)