Hands-On Design Patterns with C++

Non-member swap

The standard also provides a template std::swap() function. Prior to C++11, it was declared in the <algorithm> header; in C++11, it was moved to <utility>. The declaration of the function is as follows:

template <typename T>    void swap (T& a, T& b); template <typename T, size_t N>    void swap(T (&a)[N], T (&b)[N]);    // Since C++11

The overload for arrays was added in C++11. In C++20, both versions are additionally declared constexpr. For STL containers, std::swap() calls the member function swap(). As we will see in the following section, the behavior of swap() can be customized for other types as well, but without any special efforts, the default implementation is used. This implementation does a swap using a temporary object. ...