NAME¶

std::rbegin,std::crbegin - std::rbegin,std::crbegin

Synopsis¶

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

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

1,2) Returns c.begin(), which is typically an iterator to the beginning of the
sequence represented by c.
1) If C is a standard Container, returns a C::reverse_iterator object.
2) If C is a standard Container, returns a C::const_reverse_iterator object.
3) Returns a std::reverse_iterator<T*> object to the reverse-beginning of array.
4) Returns a std::reverse_iterator<const T*> object to the reverse-beginning of il.
5) Returns std::rbegin(c), with c always treated as const-qualified.
If C is a standard Container, returns a C::const_reverse_iterator object.

range-rbegin-rend.svg

Parameters¶

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

Return value¶

1,2) c.rbegin()
3) std::reverse_iterator<T*>(array + N)
4) std::reverse_iterator<const T*>(il.end())
5) 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 (since C++20)
std::ranges::crbegin.

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 <iterator>
#include <vector>

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 << ' ';
std::cout << '\n';
}

Output:¶

*vi = 4
*ai = 15
4 1 3

See also¶

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