# iter_swap(std::counted_iterator)

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< cpp‎ | iterator‎ | counted iterator

template< std::indirectly_swappable <I> I2 > friend constexpr void iter_swap( const counted_iterator& x, const std::counted_iterator <I2>& y ) noexcept(noexcept( ranges::iter_swap (x.base(), y.base()))); |  | (since C++20)

Swaps the objects pointed to by two underlying iterators. The behavior is undefined if either x.count() or y.count() is equal to ​0​.

The function body is equivalent to: ranges::iter_swap (x.base(), y.base());.

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

### Parameters

x, y | - | iterator adaptors to the elements to swap

### Return value

(none)

### Complexity

Constant.

### Example

Run this code

    #include <iostream>
    #include <iterator>
    #include <list>
    #include <vector>

    int main()
    {
        std::vector p{1, 2, 3, 4},
                    q{5, 6, 7, 8};

        std::counted_iterator<std::vector<int>::iterator> ip{p.begin(), 2};
        std::counted_iterator<std::vector<int>::iterator> iq{q.begin(), 3};

        std::cout << *ip << ' ' << *iq << '\n';
        iter_swap(ip, iq); // ADL
        std::cout << *ip << ' ' << *iq << '\n';

        std::list x{0, 1, 3};
        std::counted_iterator<std::list<int>::iterator> ix{x.begin(), 2};
    //  iter_swap(ip, ix); // error: not indirectly swappable
    }

Output:

    1 5
    5 1

### See also

swap | swaps the values of two objects (function template)
swap_ranges | swaps two ranges of elements (function template)
iter_swap | swaps the elements pointed to by two iterators (function template)
iter_swap (C++20) | swaps the values referenced by two dereferenceable objects (customization point object)
iter_move (C++20) | casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function)

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