std::rbegin, std::crbegin

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Iterator library

Iterator concepts
indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) input_or_output_iterator (C++20) sentinel_for (C++20) sized_sentinel_for (C++20)	input_iterator (C++20) output_iterator (C++20) forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
Iterator primitives
iterator_traits input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20) iterator (deprecated in C++17)	incrementable_traits (C++20) indirectly_readable_traits (C++20) iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(C++20)(C++20)
Algorithm concepts and utilities
Indirect callable concepts
indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20)   indirect_unary_predicate (C++20)	indirect_binary_predicate (C++20) indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
Common algorithm requirements
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20) indirectly_copyable_storable (C++20)	indirectly_swappable (C++20) indirectly_comparable (C++20) permutable (C++20) mergeable (C++20) sortable (C++20)
Utilities
indirect_result_t (C++20)	projected (C++20)
Iterator adaptors
reverse_iterator move_iterator (C++11) move_sentinel (C++20) common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20) make_const_iterator (C++23) make_const_sentinel (C++23) back_inserter front_inserter inserter
Stream iterators
istream_iterator ostream_iterator	istreambuf_iterator ostreambuf_iterator
Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)
Iterator operations
advance distance prev (C++11) next (C++11)	ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)
Range access
begincbegin (C++11)(C++14) endcend (C++11)(C++14) sizessize (C++17)(C++20)	rbegincrbegin (C++14)(C++14) rendcrend (C++14)(C++14) empty (C++17) data (C++17)

 

Defined in header <array>
Defined in header <deque>
Defined in header <forward_list>
Defined in header <iterator>
Defined in header <list>
Defined in header <map>
Defined in header <regex>
Defined in header <set>
Defined in header <span>		(since C++20)
Defined in header <string>
Defined in header <string_view>		(since C++17)
Defined in header <unordered_map>
Defined in header <unordered_set>
Defined in header <vector>
	(1)
template< class C > auto rbegin( C& c ) -> decltype(c.rbegin());			(since C++14) (until C++17)
template< class C > constexpr auto rbegin( C& c ) -> decltype(c.rbegin());			(since C++17)
		(1)
template< class C > auto rbegin( const C& c ) -> decltype(c.rbegin());				(since C++14) (until C++17)
template< class C > constexpr auto rbegin( const C& c ) -> decltype(c.rbegin());				(since C++17)
			(2)
template< class T, std::size_t N > std::reverse_iterator<T*> rbegin( T (&array)[N] );					(since C++14) (until C++17)
template< class T, std::size_t N > constexpr std::reverse_iterator<T*> rbegin( T (&array)[N] );					(since C++17)
				(3)
template< class T > std::reverse_iterator<const T*> rbegin( std::initializer_list<T> il );						(since C++14) (until C++17)
template< class T > constexpr std::reverse_iterator<const T*> rbegin(std::initializer_list<T> il);						(since C++17)
					(4)
template< class C > auto crbegin( const C& c ) -> decltype(std::rbegin(c));							(since C++14) (until C++17)
template< class C > constexpr auto crbegin( const C& c ) -> decltype(std::rbegin(c));							(since C++17)

Returns an iterator to the reverse-beginning of the given range.

1) Returns an iterator to the reverse-beginning of the possibly const-qualified container or view c.

2) Returns std::reverse_iterator<T*> to the reverse-beginning of the array array.

3) Returns std::reverse_iterator<const T*> to the reverse-beginning of the std::initializer_list il.

4) Returns an iterator to the reverse-beginning of the const-qualified container or view c.

Parameters

c	-	a container or view with a rbegin member function
array	-	an array of arbitrary type
il	-	an initializer_list

Return value

1) c.rbegin()

2) std::reverse_iterator<T*>(array + N)

3) std::reverse_iterator<const T*>(il.end())

4) c.rbegin()

Exceptions

May throw implementation-defined exceptions.

Overloads

Custom overloads of rbegin may be provided for classes and enumerations that do not expose a suitable rbegin() member function, yet can be iterated.

Overloads of rbegin found by argument-dependent lookup can be used to customize the behavior of std::ranges::rbegin and std::ranges::crbegin.

(since C++20)

Notes

The overload for std::initializer_list is necessary because it does not have a member function rbegin.

Example

Run this code

#include <iostream>
#include <vector>
#include <iterator>
 
int main() 
{
    std::vector<int> v = { 3, 1, 4 };
    auto vi = std::rbegin(v); // the type of `vi` is std::vector<int>::reverse_iterator
    std::cout << "*vi = " << *vi << '\n';
 
    *std::rbegin(v) = 42; // OK: after assignment v[2] == 42
//  *std::crbegin(v) = 13; // error: the location is read-only
 
    int a[] = { -5, 10, 15 };
    auto ai = std::rbegin(a); // the type of `ai` is std::reverse_iterator<int*>
    std::cout << "*ai = " << *ai << '\n';
 
    auto il = { 3, 1, 4 };
    // the type of `it` below is std::reverse_iterator<int const*>:
    for (auto it = std::rbegin(il); it != std::rend(il); ++it)
        std::cout << *it << ' '; 
}

Output:

*vi = 4
*ai = 15
4 1 3

See also

begincbegin (C++11)(C++14)	returns an iterator to the beginning of a container or array (function template)
endcend (C++11)(C++14)	returns an iterator to the end of a container or array (function template)
rendcrend (C++14)	returns a reverse end iterator for a container or array (function template)
ranges::rbegin (C++20)	returns a reverse iterator to a range (customization point object)
ranges::crbegin (C++20)	returns a reverse iterator to a read-only range (customization point object)