std::ranges::rend

Header: <ranges>

Returns a sentinel indicating the end of a reversed range.

# Declarations

inline namespace /* unspecified */ {
inline constexpr /* unspecified */ rend = /* unspecified */;
}

(since C++20) (customization point object)

Call signature

template< class T >
requires /* see below */
constexpr std::sentinel_for<
decltype(ranges::rbegin(std::declval<T>()))> auto rend( T&& t );

(since C++20)

# Notes

If the argument is an rvalue (i.e. T is an object type) and ranges::enable_borrowed_range<std::remove_cv_t> is false, or if it is of an array type of unknown bound, the call to ranges::rend is ill-formed, which also results in substitution failure.

If ranges::rend(std::forward(t)) is valid, then decltype(ranges::rend(std::forward(t))) and decltype(ranges::begin(std::forward(t))) model std::sentinel_for in all cases, while T models std::ranges::range.

The C++20 standard requires that if the underlying rend function call returns a prvalue, the return value is move-constructed from the materialized temporary object. All implementations directly return the prvalue instead. The requirement is corrected by the post-C++20 proposal P0849R8 to match the implementations.

# Example

#include <algorithm>
#include <iostream>
#include <ranges>
#include <vector>
 
int main()
{
    std::vector<int> v = {3, 1, 4};
    namespace ranges = std::ranges;
    if (ranges::find(ranges::rbegin(v), ranges::rend(v), 5) != ranges::rend(v))
        std::cout << "found a 5 in vector v!\n";
 
    int a[] = {5, 10, 15};
    if (ranges::find(ranges::rbegin(a), ranges::rend(a), 5) != ranges::rend(a))
        std::cout << "found a 5 in array a!\n";
}

# Defect reports

# See also

• ranges::crend
• ranges::rbegin
• rendcrend