c++ 迭代器种类，查看相应的容器的迭代器类型

标准库当中的5种迭代器类型

// ITERATOR STUFF (from )
// ITERATOR TAGS (from )
struct input_iterator_tag {};

struct output_iterator_tag {};

struct forward_iterator_tag : input_iterator_tag {};

struct bidirectional_iterator_tag : forward_iterator_tag {};

struct random_access_iterator_tag : bidirectional_iterator_tag {};

#include 
#include 
#include 
#include 

2：原理探索

iterator_traits：给进去迭代器的类型，萃取出迭代器的种类——给进去一种类型，萃取出另外一种类型。