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std::iter_swap(std::reverse_iterator)

From cppreference.com
 
 
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11)(C++14)
(C++14)(C++14)  
(C++11)(C++14)
(C++14)(C++14)  
(C++17)(C++20)
(C++17)
(C++17)
 
 
template< std::indirectly_swappable<Iter> Iter2 >

    friend constexpr void
        iter_swap( const reverse_iterator& x,

                   const std::reverse_iterator<Iter2>& y ) noexcept(/*see below*/);
(since C++20)

Swaps the objects pointed to by two adjusted underlying iterators. The function body is equivalent to:

auto tmp_x = x.base();
auto tmp_y = y.base();
ranges::iter_swap(--tmp_x, --tmp_y);

This function template is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::reverse_iterator<Iter> is an associated class of the arguments.

Contents

[edit] Parameters

x, y - reverse iterators to the elements to swap

[edit] Return value

(none)

[edit] Complexity

Constant.

[edit] Exceptions

noexcept specification:  
noexcept(

    std::is_nothrow_copy_constructible_v<Iter> &&
    std::is_nothrow_copy_constructible_v<Iter2> &&
    noexcept(ranges::iter_swap(--std::declval<Iter&>(), --std::declval<Iter2&>()))

)

[edit] Example

#include <iostream>
#include <iterator>
#include <list>
#include <vector>
 
int main()
{
    std::vector v{1, 2, 3};
    std::list l{4, 5, 6};
 
    std::reverse_iterator<std::vector<int>::iterator> r1{v.rbegin()};
    std::reverse_iterator<std::list<int>::iterator> r2{l.rbegin()};
 
    std::cout << *r1 << ' ' << *r2 << '\n';
 
    iter_swap(r1, r2); // ADL
 
    std::cout << *r1 << ' ' << *r2 << '\n';
}

Output:

3 6
6 3

[edit] See also

swaps the values of two objects
(function template) [edit]
swaps two ranges of elements
(function template) [edit]
swaps the elements pointed to by two iterators
(function template) [edit]
(C++20)
swaps the values referenced by two dereferenceable objects
(customization point object)[edit]
(C++20)
swaps the objects pointed to by two underlying iterators
(function template) [edit]