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std::iter_swap

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Defined in header <algorithm>
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template< class ForwardIt1, class ForwardIt2 >
void iter_swap( ForwardIt1 a, ForwardIt2 b );
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Swaps the values of the elements the given iterators are pointing to.

Contents

Parameters

a, b - iterators to the elements to swap
Type requirements
-
ForwardIt1, ForwardIt2 must meet the requirements of ForwardIterator.
-
*a, *b must meet the requirements of Swappable.

Return value

(none)

Complexity

constant

Possible implementation

template<class ForwardIt1, class ForwardIt2>
void iter_swap(ForwardIt1 a, ForwardIt2 b)
{
   using std::swap;
   swap(*a, *b);
}

Example

The following is an implementation of selection sort in C++

#include <random>
#include <vector>
#include <iostream>
#include <algorithm>
#include <functional>
#include <iterator>
 
template<class ForwardIt>
void selection_sort(ForwardIt begin, ForwardIt end)
{
    for (ForwardIt i = begin; i != end; ++i)
        std::iter_swap(i, std::min_element(i, end));
}
 
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<> dist(-10, 10);
    std::vector<int> v;
    generate_n(back_inserter(v), 20, bind(dist, gen));
 
    std::cout << "Before sort: ";
    copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
 
    selection_sort(v.begin(), v.end());
 
    std::cout << "\nAfter sort: ";
    copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << '\n';
}

Output:

Before sort: -7 6 2 4 -1 6 -9 -1 2 -5 10 -9 -5 -3 -5 -3 6 6 1 8
After sort: -9 -9 -7 -5 -5 -5 -3 -3 -1 -1 1 2 2 4 6 6 6 6 8 10

See also

Template:cpp/algorithm/dcl list swapTemplate:cpp/algorithm/dcl list swap ranges