std::ranges::end

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

template< class T >
    requires /* see below */
constexpr std::sentinel_for<ranges::iterator_t<T>> auto end( T&& t );

Returns a sentinel indicating the end of a range.

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 overload resolution is performed with the following candidates:
   • any declarations of end found by argument-dependent lookup.
   • void end(auto&) = delete;
   • void end(const auto&) = delete;

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.

Customization point objects

The name ranges::end 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 __end_fn.

All instances of __end_fn are equal. The effects of invoking different instances of type __end_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::end 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::end above, __end_fn models
.

• std::invocable<__end_fn, Args...>,
• std::invocable<const __end_fn, Args...>,
• std::invocable<__end_fn&, Args...>, and
• std::invocable<const __end_fn&, Args...>.
  

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

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

#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";
}

found a 5 in array arr!

See also