std::ranges::bidirectional_range

< cpp‎ | ranges
定义于头文件 <ranges>
template<class T>

  concept bidirectional_range =

    ranges::forward_range<T> && std::bidirectional_iterator<ranges::iterator_t<T>>;

bidirectional_range 概念是 range 的细化，对于实现的类型， ranges::begin 返回 bidirectional_iterator 的实现。