unordered_map< K，V> :: iterator来自哪里? [英] Where does unordered_map<K, V>::iterator come from?

问题描述

当我使用 std :: unordered_map< K，V> 时，我知道每个键值对的迭代器的类型都是 std :: unordered_map< K，V> :: iterator .我也知道迭代器本身指向 pair< const K，V> .但是，我知道迭代器指向一对的唯一原因是查看示例代码.在哪里定义此行为?

When I'm using a std::unordered_map<K, V> I know that the iterator to each key-value pair is of type std::unordered_map<K, V>::iterator. I also know that the iterator itself points to a pair<const K, V>. However, the only reason I know the iterator points to a pair is from looking at example code. Where is this behavior defined?

例如，如果我访问 cppreference.com上的文档，我看不到此行为的解释.它只说成员 iterator 被定义为 ForwardIterator .

For example, if I go to the documentation at cppreference.com, I don't see where this behavior is explained. It only says that the member iterator is defined as a ForwardIterator.

所以，我的问题是，聪明的开发人员如何知道 std :: unordered_map< K，V> :: iterator 实际代表什么?我确定我缺少一些合乎逻辑的飞跃.

So, my question is, how would a smart developer know what a std::unordered_map<K, V>::iterator actually represents? I'm sure there is some logical leap I'm missing.

推荐答案

用于STL容器

个对象将返回类型为 reference 的对象，该对象是对类型为 value_type 的对象的引用.

objects of type iterator when de-referenced return an object of type reference, which is a reference to an object of type value_type.

这些都是在容器内部定义的.

These are all defined inside the container.

请注意，将std :: map定义为容器.此信息是本文档的一部分.

Note the std::map is defined as a container. This information is part of this documentation.

https://en.cppreference.com/w/cpp/named_req/Container

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