std::ranges::end

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 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.

Customization point objects

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

[edit] 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.

[edit] 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!

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also