Defined in header <ranges>
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)

Returns a sentinel indicating the end of a reversed range.


Let t be an object of type T. If the argument is an lvalue or ranges::enable_borrowed_range<std::remove_cv_t<T>> is true, then a call to ranges::rend is expression-equivalent to:

  1. t.rend() converted to its decayed type, if that expression with conversion is valid, and its converted type models std::sentinel_for<decltype(ranges::rbegin(std::declval<T>()))>.
  2. Otherwise, rend(t) converted to its decayed type, if T is a class or enumeration type, the aforementioned unqualified call with conversion is valid, and its converted type models std::sentinel_for<decltype(ranges::rbegin(std::declval<T>()))>, where the overload resolution is performed with the following candidates:
  3. Otherwise, std::make_reverse_iterator(ranges::begin(t)) if both ranges::begin(t) and ranges::end(t) are valid expressions, have the same type, and that type models std::bidirectional_iterator.

In all other cases, a call to ranges::rend is ill-formed, which can result in substitution failure when ranges::rend(t) appears in the immediate context of a template instantiation.


Expression e is expression-equivalent to expression f, if.

  • e and f have the same effects, and
  • either both are constant subexpressions or else neither is a constant subexpression, and
  • either both are potentially-throwing or else neither is potentially-throwing (i.e. noexcept(e) == noexcept(f)).

Customization point objects

The name ranges::rend denotes a customization point object, which is a const function object of a literal semiregular class type. For exposition purposes, the cv-unqualified version of its type is denoted as __rend_fn.

All instances of __rend_fn are equal. The effects of invoking different instances of type __rend_fn on the same arguments are equivalent, regardless of whether the expression denoting the instance is an lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified instance is not required to be invocable). Thus, ranges::rend can be copied freely and its copies can be used interchangeably.

Given a set of types Args..., if std::declval<Args>()... meet the requirements for arguments to ranges::rend above, __rend_fn models

Otherwise, no function call operator of __rend_fn participates in overload resolution.


If the argument is an rvalue (i.e. T is an object type) and ranges::enable_borrowed_range<std::remove_cv_t<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>(t)) is valid, then decltype(ranges::rend(std::forward<T>(t))) and decltype(ranges::begin(std::forward<T>(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.


#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";


found a 5 in array `a`!

See also

returns a reverse end iterator to a read-only range
(customization point object)
returns a reverse iterator to a range
(customization point object)
returns a reverse end iterator for a container or array
(function template)

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