std::rbegin, std::crbegin

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

#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

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)