Millistel juhtudel ja milliste objektidega kasutatakse C++-s using direktiivi?

In C++, the using directive is used to simplify access to names from namespaces or to create type aliases.

Main use cases:

1. Including names from a namespace:

using namespace std; // allows using names from std without the std prefix

2. Including a specific name:

using std::cout; // now you can write cout instead of std::cout

3. Creating type aliases:

using IntVector = std::vector<int>; // alias for the type

The using directive makes code reading and writing easier, reducing the need to write long qualified names.