NAME¶

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

Synopsis¶

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>
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( C++14)
T (&array)[N] ); (until
C++17)
template< class T, std::size_t N > (1)
constexpr (since
std::reverse_iterator<T*> rbegin( C++17)
T (&array)[N] );
template< class T > (1) (since
std::reverse_iterator<const T*> C++14)
rbegin( std::initializer_list<T> (until
il ); (2) C++17)
template< class T >
constexpr (since
std::reverse_iterator<const T*> C++17)
rbegin(std::initializer_list<T> (3)
il);
template< class C > (since
auto crbegin( const C& c ) -> C++14)
decltype(std::rbegin(c)); (until
(4) 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) 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.

range-rbegin-rend.svg

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 (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 <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¶

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)