std::rbegin, std::crbegin - cppreference.com

template< class C >
auto rbegin( C& c ) noexcept(noexcept(c.rbegin()))
    -> decltype(c.rbegin());

template< class C >
auto rbegin( const C& c ) noexcept(noexcept(c.rbegin()))
    -> decltype(c.rbegin());

template< class T, std::size_t N >
std::reverse_iterator<T*> rbegin( T (&array)[N] ) noexcept;

template< class T >
std::reverse_iterator<const T*> rbegin( std::initializer_list<T> il ) noexcept;

template< class C >
auto crbegin( const C& c ) noexcept(noexcept(std::rbegin(c)))
    -> decltype(std::rbegin(c));

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.

Parameters

Return value

1,2) c.rbegin()

3) std::reverse_iterator<T*>(array + N)

4) std::reverse_iterator<const T*>(il.end())

5) std::rbegin(c)

Exceptions

1,2) What and when underlying c.rbegin() call throws.

5) What and when underlying std::rbegin(c) call throws.

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.

Notes

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

Example

#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';
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also