_map_citr _map_itr _map_key2entry _size _values begin begin clear const_iterator empty end end EntryType erase erase find find HashMap insert insert iterator operator== operator[] size

begin() [1/2] template<class KeyType , class MappedType , class Hash = std::hash<KeyType>, class Pred = std::equal_to<KeyType>> iterator begin ( ) 获取首元素的迭代器 获取首元素的迭代器 返回 首元素的迭代器