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iter_swap(std::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.

Equivalent to ranges::iter_swap(x.base(), y.base());.

If x.count > 0 && y.count() > 0 is false, the behavior is undefined.

(until C++26)

If x.count > 0 && y.count() > 0 is false:

  • If the implementation is hardened, a contract violation occurs.
  • If the implementation is not hardened, the behavior is undefined.
(since C++26)

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

Complexity

Constant.

Example

#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 & algorithm function object)
ranges::swap_ranges
(C++20)
iter_swap
swaps the elements pointed to by two iterators
(function template)
ranges::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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Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/cpp/iterator/counted_iterator/iter_swap

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