Returns an iterator to the last element of the argument.

IfT is an array type andstd::remove_all_extents_t<std::remove_reference_t<T>> is incomplete, then the call toranges::rbegin is ill-formed, no diagnostic required.

If the argument is an lvalue orranges::enable_borrowed_range<std::remove_cv_t<T>> istrue, then a call toranges::rbegin isexpression-equivalent to:

1. decay-copy(t.rbegin())(until C++23)auto(t.rbegin())(since C++23), if that expression is valid and its type modelsstd::input_or_output_iterator.
2. Otherwise,decay-copy(rbegin(t))(until C++23)auto(rbegin(t))(since C++23), ifT is a class or enumeration type, that expression is valid and its type modelsstd::input_or_output_iterator, where the meaning ofrbegin is established as if by performingargument-dependent lookup only.
3. Otherwise,std::make_reverse_iterator(ranges::end(t)) if bothranges::begin(t) andranges::end(t) are valid expressions, have the same type, and that type modelsstd::bidirectional_iterator.

In all other cases, a call toranges::rbegin is ill-formed, which can result insubstitution failure whenranges::rbegin(t) appears in the immediate context of a template instantiation.

Customization point objects

The nameranges::rbegin denotes acustomization point object, which is a constfunction object of aliteralsemiregular class type. SeeCustomizationPointObject for details.

[edit]Notes

If the argument is an rvalue (i.e.T is an object type) andranges::enable_borrowed_range<std::remove_cv_t<T>> isfalse, the call toranges::rbegin is ill-formed, which also results in substitution failure.

The return type modelsstd::input_or_output_iterator in all cases.

The C++20 standard requires that if the underlyingrbegin 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 proposalP0849R8 to match the implementations.

[edit]Example

#include <iostream>#include <ranges>#include <span>#include <vector> int main(){std::vector<int> v={3,1,4};auto vi= std::ranges::rbegin(v);std::cout<<*vi<<'\n';*vi=42;// OK int a[]={-5,10,15};auto ai= std::ranges::rbegin(a);std::cout<<*ai<<'\n';*ai=42;// OK // auto x_x = std::ranges::rbegin(std::vector{6, 6, 6});// ill-formed: the argument is an rvalue (see Notes ↑) auto si= std::ranges::rbegin(std::span{a});// OK    static_assert(std::ranges::enable_borrowed_range<std::remove_cv_t<decltype(std::span{a})>>);*si=42;// OK}

415

[edit]Defect reports

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

[edit]See also

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