Swap and the standard template library

The swap operation is widely used in the C++ standard library. All Standard Template Library (STL) containers provide swap functionality, and there is a non-member function template, std::swap. There are also uses of swap in STL algorithms. The standard library is also a template for implementing custom features that resemble standard ones. Therefore, we'll begin our study of the swap operation with a look at the functionality provided by the standard.

Swap and STL containers

Conceptually, swap is equivalent to the following operation:

template <typename T> void swap(T& x, T& y) { 
    T tmp(x);
    x = y;
    y = tmp;
}

After the swap() is called, the contents of the...