std::rbegin, std::crbegin

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
Stream iterators
istream_iterator
ostream_iterator
istreambuf_iterator
ostreambuf_iterator
Iterator operations
advance
distance
prev (C++11)
next (C++11)
Range access
begincbegin (C++11)(C++14)
endcend (C++11)(C++14)
rbegincrbegin (C++14)(C++14)
rendcrend (C++14)(C++14)
Container access
sizessize (C++17)(C++20)
empty (C++17)
data (C++17)

 

Defined in header <iterator>
	(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, size_t N > reverse_iterator<T*> rbegin( T (&array)[N] );					(since C++14) (until C++17)
template< class T, size_t N > constexpr reverse_iterator<T*> rbegin( T (&array)[N] );					(since C++17)
				(3)
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 container c or array array.

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

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

3) Returns a const-qualified iterator to the reverse-beginning of the container c.

Parameters

c	-	a container with a rbegin method
array	-	an array of arbitrary type

Return value

An iterator to the reverse-beginning of c or array

Notes

In addition to being included in <iterator>, std::rbegin and std::crbegin are guaranteed to become available if any of the following headers are included: <array>, <deque>, <forward_list>, <list>, <map>, <regex>, <set>, <span> (since C++20), <string>, <string_view> (since C++17), <unordered_map>, <unordered_set>, and <vector>.

Overloads

Custom overloads of rbegin may be provided for classes that do not expose a suitable rbegin() member function, yet can be iterated. The following overload is already provided by the standard library:

rbegin(std::initializer_list) (C++14)

specializes std::rbegin (function)

Example

Run this code

#include <iostream>
#include <vector>
#include <iterator>
 
int main() 
{
    std::vector<int> v = { 3, 1, 4 };
    auto vi = std::rbegin(v);
    std::cout << *vi << '\n'; 
 
    int a[] = { -5, 10, 15 };
    auto ai = std::rbegin(a);
    std::cout << *ai << '\n';
}

Output:

4
15

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)