std::ranges::reverse

Since C++20

Header: <algorithm>

  1. Reverses the order of the elements in the range [first,last).

# Declarations

Call signature

template< std::bidirectional_iterator I, std::sentinel_for<I> S >
requires std::permutable<I>
constexpr I
reverse( I first, S last );

(since C++20)

template< ranges::bidirectional_range R >
requires std::permutable<ranges::iterator_t<R>>
constexpr ranges::borrowed_iterator_t<R>
reverse( R&& r );

(since C++20)

# Parameters

# Return value

An iterator equal to last.

# Notes

Implementations (e.g. MSVC STL) may enable vectorization when the iterator type models contiguous_iterator and swapping its value type calls neither non-trivial special member function nor ADL-found swap.

# Example

#include <algorithm>
#include <array>
#include <iostream>
#include <string>
 
int main()
{
    std::string s {"ABCDEF"};
    std::cout << s << " → ";
    std::ranges::reverse(s.begin(), s.end());
    std::cout << s << " → ";
    std::ranges::reverse(s);
    std::cout << s << " │ ";
 
    std::array a {1, 2, 3, 4, 5};
    for (auto e : a)
        std::cout << e << ' ';
    std::cout << "→ ";
    std::ranges::reverse(a);
    for (auto e : a)
        std::cout << e << ' ';
    std::cout << '\n';
}

# See also