NAME¶

std::ranges::cend - std::ranges::cend

Synopsis¶

Defined in header <ranges>
inline namespace /*unspecified*/ {
(since C++20)
inline constexpr /*unspecified*/ cend = /*unspecified*/; (customization point
object)
}
Call signature
template< class T >

requires /* see below */ (since C++20)

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

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

range-begin-end.svg

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)).

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)).

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.

Example¶

// Run this code

#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";
}
}

Output:¶

found a 5 in array a!

See also¶

ranges::end returns a sentinel indicating the end of a range
(C++20) (customization point object)
end
cend returns an iterator to the end of a container or array
(C++11) (function template)
(C++14)