C++ Algorithm Library - iter_swap() Function

Description

The C++ function std::algorithm::iter_swap() exchange values of objects pointed by two iterators. It uses function swap (unqualified) to exchange the elements.

Declaration

Following is the declaration for std::algorithm::iter_swap() function form std::algorithm header.

C++98

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

Parameters

• a − First forward iterator object.

• b − Second forward iterator object.

Return value

None

Exceptions

Throws exception if swap function throws an exception.

Please note that invalid parameters cause undefined behavior.

Time complexity

Constant.

Example

The following example shows the usage of std::algorithm::iter_swap() function.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(void) {
   vector<int> v1 = {1, 2, 3, 4, 5};
   vector<int> v2 = {10, 20, 30, 40, 50};

   iter_swap(v1.begin(), v2.begin());
   iter_swap(v1.begin() + 1, v2.begin() + 2);

   cout << "Vector v2 contains following elements" << endl;

   for (auto it = v2.begin(); it != v2.end(); ++it)
      cout << *it << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Vector v2 contains following elements
1
20
2
40
50