C++ Primer Plus

Namespaces

If you use iostream instead of iostream.h, you should use the following namespace directive to make the definitions in iostream available to your program:

using namespace std;

This is called a using directive. The simplest thing to do is to accept this for now and worry about it later (for example, in Chapter 9, “Memory Models and Namespaces”). But so you won’t be left completely in the dark, here’s an overview of what’s happening.

Namespace support is a C++ feature designed to simplify the writing of large programs and of programs that combine pre-existing code from several vendors and to help organize programs. One potential problem is that you might use two prepackaged products that both have, say, a function called wanda(). If ...