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std::rend, std::crend

From cppreference.com
< cpp‎ | iterator
 
 
Iterator library
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Iterator operations
(C++11)
(C++11)
Range access
(C++11)(C++14)
(C++11)(C++14)
(C++17)(C++20)
(C++14)(C++14)
rendcrend
(C++14)(C++14)
(C++17)
(C++17)
 
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>
(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, std::size_t N >
std::reverse_iterator<T*> rend( T (&array)[N] );
(since C++14)
(until C++17)
template< class T, std::size_t N >
constexpr std::reverse_iterator<T*> rend( T (&array)[N] );
(since C++17)
(3)
template< class T >
std::reverse_iterator<const T*> rend( std::initializer_list<T> il );
(since C++14)
(until C++17)
template< class T >
constexpr std::reverse_iterator<const T*> rend( std::initializer_list<T> il );
(since C++17)
(4)
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 range.

1) Returns an iterator to the reverse-end of the possibly const-qualified container or view c.
2) Returns std::reverse_iterator<T*> to the reverse-end of the array array.
3) Returns std::reverse_iterator<const T*> to the reverse-end of the std::initializer_list il.
4) Returns an iterator to the reverse-end of the const-qualified container or view c.

range-rbegin-rend.svg

Contents

[edit] Parameters

c - a container or view with a rend member function
array - an array of arbitrary type
il - an initializer_list

[edit] Return value

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

[edit] Exceptions

May throw implementation-defined exceptions.

[edit] 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 customize the behavior of std::ranges::rend and std::ranges::crend.

(since C++20)

[edit] Notes

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

[edit] Example

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
 
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::cout << "\nstd::vector `v` 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:

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

[edit] See also

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