In this article, we’d shed some light on the implementation of ranges::reverse_view and std::views::reverse. We’ll compare them to understand the differences between views and their adaptor objects.

Understanding Ranges Views and View Adaptors Objects in C++20/C++23

By Bartlomiej Filipek

From the article:

Let’s look at an example to understand how these views work. Assume we have a range r of integers from 1 to 5. When we apply std::views::reverse to r, it creates a view representing the elements of r in the reverse order.

#include <ranges> 
#include <vector> 
#include <iostream>  

int main() {
  std::vector<int> r = {1, 2, 3, 4, 5};  
  auto reversed = r | std::views::reverse;  
  for (auto i : reversed)  
     std::cout << i << " ";   

  // same as:  
  for (auto i : r | std::views::reverse)  
     std::cout << i << " "; 
}