< cpp‎ | ranges
Ranges library
Range access
Range conversions
Range primitives

Dangling iterator handling
Range concepts


Range generators
Range adaptor objects
Range adaptor closure objects
Helper items
Defined in header <ranges>
inline namespace /* unspecified */ {

    inline constexpr /* unspecified */ cend = /* unspecified */;

(since C++20)
(customization point object)
Call signature
template< class T >

    requires /* see below */

constexpr std::sentinel_for<ranges::iterator_t<T>> auto cend( T&& t );
(since C++20)

Returns a sentinel indicating the end of a const-qualified range.


Let CT be

  1. const std::remove_reference_t<T>& if the argument is an lvalue (i.e. T is an lvalue reference type),
  2. const T otherwise,

a call to ranges::cend is expression-equivalent to ranges::end(static_cast<CT&&>(t)).

If ranges::cend(e) is valid for an expression e, where decltype((e)) is T, then CT models std::ranges::range, and std::sentinel_for<S, I> is true in all cases, where S is decltype(ranges::cend(e)), and I is decltype(ranges::cbegin(e)).


[edit] Expression-equivalent

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)).

[edit] Customization point objects

The name ranges::cend 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 __cend_fn.

All instances of __cend_fn are equal. The effects of invoking different instances of type __cend_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::cend 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::cend above, __cend_fn models

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

[edit] Example

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


Found a 5 in array arr!

[edit] See also

returns a sentinel indicating the end of a range
(customization point object) [edit]
returns an iterator to the end of a container or array
(function template) [edit]