iterator adaptors - insert iterators

最新推荐文章于 2025-06-28 06:00:00 发布

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#insert #iterator #function #each

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本文介绍了三种不同的插入迭代器及其常用操作技巧。通过两步法实现插入操作：首先，使用无操作符将迭代器自身返回；其次，通过赋值操作调用容器的成员函数如 push_back(), push_front() 或 insert() 来完成元素的插入。文章还提供了具体的代码示例来展示如何使用这些插入迭代器。

Three different insert iterators

The trick Operations:

Implementations of insert iterators usually use the following two-step trick:
1) Operator * is implemented as a no-op that simply returns *this. Thus, for insert iterators, *pos is equivalent to pos.
2) The assignment operator is implemented so that it gets transferred into an insertion. In fact, the insert iterator calls the push_back(), push_front(), or insert() member function of the container.

Since each inserter uses a different member function, which it calls for the container to which it belongs, an insert iterator must be always initialized with its container.
vector<int> coll;
back_insert_iterator<decltype(coll)> iter(coll);
*iter = 1; // insert
*iter = 2; // insert

set<int> coll2;

insert_iterator<decltype(coll1)> iter2(coll2, coll2.begin());
*iter = 1;
*iter = 2;
*iter = 3;
inserter(coll2,coll2.end()) = 44;

list<int> coll3;
copy (coll2.begin(), col2l.end(), // source
inserter(coll3,coll3.begin())); // destination