The Boost C++ Libraries

Chapter 71. Boost.Swap

If you use many Boost libraries and also use std::swap() to swap data, consider using boost::swap() as an alternative. boost::swap() is provided by Boost.Swap and is defined in boost/swap.hpp.

Example 71.1. Using boost::swap()
#include <boost/swap.hpp>
#include <boost/array.hpp>
#include <iostream>

int main()
  char c1 = 'a';
  char c2 = 'b';

  boost::swap(c1, c2);

  std::cout << c1 << c2 << '\n';

  boost::array<int, 1> a1{{1}};
  boost::array<int, 1> a2{{2}};

  boost::swap(a1, a2);

  std::cout << a1[0] << a2[0] << '\n';

boost::swap() does nothing different from std::swap(). However, because many Boost libraries offer specializations for swapping data that are defined in the namespace boost, boost::swap() can take advantage of them. In Example 71.1, boost::swap() accesses std::swap() to swap the values of the two char variables and uses the optimized function boost::swap() from Boost.Array to swap data in the arrays.

Example 71.1 writes ba and 21 to the standard output stream.