From cppreference.com
Defined in header
Defined in header
inlinenamespace/* unspecified */{inlineconstexpr/* unspecified */end=/* unspecified */;}(since C++20)
(customization point object)Call signature
template<classT>requires/* see below */constexprstd::sentinel_for<ranges::iterator_t<T>>autoend(T&&t);(since C++20)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
to:
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,
.
Otherwise,
(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>>.
Otherwise,
(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
only.
In all other cases, a call to ranges::end is ill-formed, which can result in
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
of a
class type. See
for details.
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
in all cases, while T models
.
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
to match the implementations.
Example
Run this code
#include<algorithm>#include<iostream>#include<ranges>#include<vector>intmain(){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";intarr[]{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
C++20 there's machinery to prohibit certain non-member end found by
removed such machinery See also
(C++20)
returns a sentinel indicating the end of a read-only range
(customization point object)
(C++20)
returns an iterator to the beginning of a range
(customization point object)
(C++11)(C++14)
returns an iterator to the end of a container or array
(function template)