std:: rbegin, std:: crbegin

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(C++11) (C++14)
rbegin crbegin
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
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 <inplace_vector>
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 >
auto rbegin ( C & c ) - > decltype ( c. rbegin ( ) ) ;
(1) (since C++14)
(constexpr since C++17)
template < class C >
auto rbegin ( const C & c ) - > decltype ( c. rbegin ( ) ) ;
(2) (since C++14)
(constexpr since C++17)
template < class T, std:: size_t N >
std:: reverse_iterator < T * > rbegin ( T ( & array ) [ N ] ) ;
(3) (since C++14)
(constexpr since C++17)
template < class T >
std:: reverse_iterator < const T * > rbegin ( std:: initializer_list < T > il ) ;
(4) (since C++14)
(constexpr since C++17)
template < class C >
auto crbegin ( const C & c ) - > decltype ( std :: rbegin ( c ) ) ;
(5) (since C++14)
(constexpr since C++17)

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

1,2) Returns c. rbegin ( ) , which is typically an iterator to the reverse-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 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 <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

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