std::ranges::end(3)

NAME
std::ranges::end - std::ranges::end

Synopsis
   Defined in header <ranges>
   Defined in header <iterator>
   inline namespace /* unspecified */ {
                        (since C++20)
       inline constexpr /* unspecified */ end = /* unspecified (customization point
   */; object)
   }
   Call signature
   template< class T >
       requires /* see below */ (since C++20)
   constexpr std::sentinel_for<ranges::iterator_t<T>> auto end(
   T&& t );
   Returns a sentinel indicating the end of a range.
   range-begin-end.svg
   If the argument is an lvalue or ranges::enable_borrowed_range<std::remove_cv_t<T>>
   is true, then a call to ranges::end is expression-equivalent to:
    1. t + std::extent_v<T> if t has an array type of known bound.
          * If std::remove_all_extents_t<std::remove_reference_t<T>> is incomplete,
            then the call to ranges::end is ill-formed, no diagnostic required.
    2. Otherwise,
       decay-copy(t.end())
       (until C++23)
       auto(t.end())
       (since C++23), if that expression is valid, and its type models
       std::sentinel_for<ranges::iterator_t<T>>.
    3. Otherwise,
       decay-copy(end(t))
       (until C++23)
       auto(end(t))
       (since C++23), if T is a class or enumeration type, that expression is valid and
       its converted type models std::sentinel_for<ranges::iterator_t<T>>, where the
       meaning of end is established as if by performing argument-dependent lookup
       only.
   In all other cases, a call to ranges::end is ill-formed, which can result in
   substitution failure when the call to ranges::end appears in the immediate context
   of a template instantiation.

Notes
   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::end is ill-formed, which also results in
   substitution failure.
   If ranges::end(std::forward<T>(t)) is valid, then
   decltype(ranges::end(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 end 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.

Example
// Run this code
 #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::end(vec))
         std::cout << "found a 5 in vector vec!\n";
     int arr[]{5, 10, 15};
     if (std::ranges::find(arr, 5) != std::ranges::end(arr))
         std::cout << "found a 5 in array arr!\n";
 }

Output:
 found a 5 in array arr!
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
     DR Applied to Behavior as published Correct behavior
   P2602R2 C++20 there's machinery to prohibit certain removed such machinery
                      non-member end found by ADL

See also
   ranges::cend returns a sentinel indicating the end of a read-only range
   (C++20) (customization point object)
   ranges::begin returns an iterator to the beginning 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)