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std::ranges::cend - cppreference.com

From cppreference.com

Defined in header <ranges>

Defined in header <iterator>

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

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

Call signature

template< class T > requires /* see below */ constexpr /* see below */ auto cend( T&& t );

 (since C++20)

Returns a sentinel for the constant iterator(since C++23) indicating the end of a const-qualified(until C++23) range.

Let CT be

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

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

(until C++23)

If the argument is an lvalue or ranges::enable_borrowed_range<std::remove_cv_t<T>> is true, then a call to ranges::cend is expression-equivalent to:

  • std::const_sentinel<decltype(U)>(U) for some expression U equivalent to ranges::end(possibly-const-range(t)).

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

(since C++23)

If ranges::cend(e) is valid for an expression e, where decltype((e)) is T, then CT models std::ranges::range, and(until C++23) std::sentinel_for<S, I> is true in all cases, where S is decltype(ranges::cend(e)), and I is decltype(ranges::cbegin(e)). Additionally, S models constant-iterator if it models input_iterator.(since C++23)

Customization point objects

The name ranges::cend denotes a customization point object, which is a const function object of a literal semiregular class type. See CustomizationPointObject for details.

Example

#include <algorithm>
#include <cassert>
#include <ranges>
#include <vector>

int main()
{
    std::vector vec{3, 1, 4};
    int arr[]{5, 10, 15};

    assert(std::ranges::find(vec, 5) == std::ranges::cend(vec));
    assert(std::ranges::find(arr, 5) != std::ranges::cend(arr));
}

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]