std::iter_swap

template <class ForwardIterator1, class ForwardIterator2>  void iter_swap (ForwardIterator1 a, ForwardIterator2 b);

Exchange values of objects pointed to by two iterators

Swaps the elements pointed to by a and b.

The function calls swap (unqualified) to exchange the elements.

The behavior of this function template is equivalent to:

template <class ForwardIterator1, class ForwardIterator2>
  void iter_swap (ForwardIterator1 a, ForwardIterator2 b)
{
  swap (*a, *b);
}

Parameters

a, b: Forward iterators to the objects to swap.
swap shall be defined to exchange values of the type pointed to by the iterators.

Return value

none

Example

// iter_swap example
#include <iostream>     // std::cout
#include <algorithm>    // std::iter_swap
#include <vector>       // std::vector

int main () {

  int myints[]={10,20,30,40,50 };              //   myints:  10  20  30  40  50
  std::vector<int> myvector (4,99);            // myvector:  99  99  99  99

  std::iter_swap(myints,myvector.begin());     //   myints: [99] 20  30  40  50
                                               // myvector: [10] 99  99  99

  std::iter_swap(myints+3,myvector.begin()+2); //   myints:  99  20  30 [99] 50
                                               // myvector:  10  99 [40] 99

  std::cout << "myvector contains:";
  for (std::vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}

Output:

myvector contains: 10 99 40 99

Complexity

Constant: Calls swap once.

Data races

The objects pointed to by both iterators are modified.

Exceptions

Throws if the call to swap throws.
Note that invalid arguments cause undefined behavior.