如何为C++20的input/output/forward迭代器概念撰写单行粗略总结？

云原生阿岚

2026-7-8

C++20迭代器概念可视化补充方案

针对你缺失的三个迭代器概念，给出符合现有风格的单行概述，并更新可视化代码如下：

三个迭代器的单行含义

input_iterator：可读、单遍遍历、可与哨位比较相等性
output_iterator：可写、单遍遍历、专注输出数据
forward_iterator：可读可写（按需支持）、多遍遍历、自身可作为哨位

更新后的可视化代码

digraph iter_concepts {

rankdir = BT;

node[shape=record];

indirectly_readable [label="{indirectly_readable|... = *it}"];
indirectly_writable [label="{indirectly_writable|*it = ...}"];
weakly_incrementable [label="{weakly_incrementable|++it, one pass}"];
incrementable [label="{incrementable|++it, multi pass}"];
input_or_output_iterator [label="{input_or_output_iterator|*it}"];
sentinel_for [label="{sentinel_for|for(x : ...)}"];
sized_sentinel_for [label="{sized_sentinel_for|for(... i<sz ...)}"];
input_iterator [label="{input_iterator|可读、单遍、可与哨位比较}"];
output_iterator [label="{output_iterator|可写、单遍、专注输出}"];
forward_iterator [label="{forward_iterator|多遍、自身为哨位、可读可写}"];
bidirectional_iterator [label="{bidirectional_iterator| --it}"];
random_access_iterator [label="{random_access_iterator| it+=n, it-=n, it[n]}"];
contiguous_iterator [label="{contiguous_iterator| it ≍ pointer}"];


incrementable -> weakly_incrementable;
input_or_output_iterator -> weakly_incrementable;
sentinel_for -> input_or_output_iterator;
sized_sentinel_for -> sentinel_for;
input_iterator -> input_or_output_iterator;
input_iterator -> indirectly_readable;
output_iterator -> input_or_output_iterator;
output_iterator -> indirectly_writable;
forward_iterator -> input_iterator;
forward_iterator -> sentinel_for;
forward_iterator -> incrementable;
bidirectional_iterator -> forward_iterator;
random_access_iterator -> bidirectional_iterator;
contiguous_iterator -> random_access_iterator;

}