std::rend,std::crend(3)

NAME
std::rend,std::crend - std::rend,std::crend

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 rend( C& c ) -> C++14)
   decltype(c.rend()); (until
                        C++17)
   template< class C > (since
   constexpr auto rend( C& c ) -> C++17)
   decltype(c.rend());
   template< class C > (since
   auto rend( const C& c ) -> C++14)
   decltype(c.rend()); (until
                        C++17)
   template< class C > (since
   constexpr auto rend( const C& c ) -> C++17)
   decltype(c.rend());
   template< class T, std::size_t N > (since
   std::reverse_iterator<T*> rend( T C++14)
   (&array)[N] ); (until
                        (1) C++17)
   template< class T, std::size_t N > (since
   constexpr std::reverse_iterator<T*> C++17)
   rend( T (&array)[N] );
   template< class T > (2) (since
   std::reverse_iterator<const T*> C++14)
   rend( std::initializer_list<T> il ); (until
                        (3) C++17)
   template< class T >
   constexpr (since
   std::reverse_iterator<const T*> C++17)
   rend( std::initializer_list<T> il ); (4)
   template< class C > (since
   auto crend( const C& c ) -> C++14)
   decltype(std::rend(c)); (until
                        (5) C++17)
   template< class C > (since
   constexpr auto crend( const C& c ) C++17)
   -> decltype(std::rend(c));
   Returns an iterator to the reverse-end of the given range.
   1,2) Returns c.rend(), which is typically an iterator one past the reverse-end 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 an std::reverse_iterator<T*> object to the reverse-end of array.
   4) Returns an std::reverse_iterator<const T*> object to the reverse-end of il.
   5) Returns std::end(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 rend member function
   array - an array of arbitrary type
   il - an std::initializer_list

Return value
   1,2) c.rend()
   3) std::reverse_iterator<T*>(array)
   4) std::reverse_iterator<const T*>(il.begin())
   5) c.rend()

Exceptions
   May throw implementation-defined exceptions.
   Overloads
   Custom overloads of rend may be provided for classes and enumerations that do not
   expose a suitable rend() member function, yet can be iterated.
   Overloads of rend found by argument-dependent lookup can be used to (since C++20)
   customize the behavior of std::ranges::rend and std::ranges::crend.

Notes
   The overload for std::initializer_list is necessary because it does not have a
   member function rend.

Example
// Run this code
 #include <algorithm>
 #include <iostream>
 #include <iterator>
 #include <vector>
 int main()
 {
     int a[]{4, 6, -3, 9, 10};
     std::cout << "C-style array `a` backwards: ";
     std::copy(std::rbegin(a), std::rend(a), std::ostream_iterator<int>(std::cout, " "));
     auto il = {3, 1, 4};
     std::cout << "\nstd::initializer_list `il` backwards: ";
     std::copy(std::rbegin(il), std::rend(il), std::ostream_iterator<int>(std::cout, " "));
     std::vector<int> v{4, 6, -3, 9, 10};
     std::cout << "\nstd::vector `v` backwards: ";
     std::copy(std::rbegin(v), std::rend(v), std::ostream_iterator<int>(std::cout, " "));
     std::cout << '\n';
 }

Output:
 C-style array `a` backwards: 10 9 -3 6 4
 std::initializer_list `il` backwards: 4 1 3
 std::vector `v` backwards: 10 9 -3 6 4

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