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std::rend, std::crend

Defined in header `<iterator>`
	(1)
template< class C > auto rend( C& c ) -> decltype(c.rend());		(since C++14) (until C++17)
template< class C > constexpr auto rend( C& c ) -> decltype(c.rend());		(since C++17)
	(1)
template< class C > auto rend( const C& c ) -> decltype(c.rend());		(since C++14) (until C++17)
template< class C > constexpr auto rend( const C& c ) -> decltype(c.rend());		(since C++17)
	(2)
template< class T, size_t N > reverse_iterator<T*> rend( T (&array)[N] );		(since C++14) (until C++17)
template< class T, size_t N > constexpr reverse_iterator<T*> rend( T (&array)[N] );		(since C++17)
	(3)
template< class C > auto crend( const C& c ) -> decltype(std::rend(c));		(since C++14) (until C++17)
template< class C > constexpr auto crend( const C& c ) -> decltype(std::rend(c));		(since C++17)

Returns an iterator to the reverse-end of the given container c or array array.

1) Returns a possibly const-qualified iterator to the reverse-end of the container c.

2) Returns std::reverse_iterator<T*> to the reverse-end of the array array.

3) Returns a const-qualified iterator to the reverse-end of the container c.

Parameters

c	-	a container with a `rend` method
array	-	an array of arbitrary type

Return value

An iterator to the reverse-end of c or array.

Notes

In addition to being included in <iterator>, std::rend and std::crend 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 rend may be provided for classes that do not expose a suitable rend() member function, yet can be iterated. The following overload is already provided by the standard library:

rend(std::initializer_list)

(C++14)

specializes std::rend
(function)

Example

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
 
int main()
{
    int a[] = {4, 6, -3, 9, 10};
    std::cout << "Array backwards: ";
    std::copy(std::rbegin(a), std::rend(a), std::ostream_iterator<int>(std::cout, " "));
 
    std::cout << "\nVector backwards: ";
    std::vector<int> v = {4, 6, -3, 9, 10};
    std::copy(std::rbegin(v), std::rend(v), std::ostream_iterator<int>(std::cout, " "));
}

Output:

Array backwards: 10 9 -3 6 4 
Vector backwards: 10 9 -3 6 4