< cpp‎ | ranges
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);

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 a 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, either are both potentially-throwing or are both not potentially-throwing (i.e. noexcept(e) == noexcept(f)), and either are both constant subexpressions or are both not constant subexpressions.

[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 std::invocable<__cend_fn, Args...>, std::invocable<const __cend_fn, Args...>, std::invocable<__cend_fn&, Args...>, and std::invocable<const __cend_fn&, Args...>. 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> v = { 3, 1, 4 };
    namespace ranges = std::ranges;
    if (ranges::find(v, 5) != ranges::cend(v)) {
        std::cout << "found a 5 in vector v!\n";
    int a[] = { 5, 10, 15 };
    if (ranges::find(a, 5) != ranges::cend(a)) {
        std::cout << "found a 5 in array a!\n";


found a 5 in array a!

[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]