C++ Primer Plus

The C++ Preprocessor and the iostream File

Here’s the short version of what you need to know. If your program is to use the usual C++ input or output facilities, you provide these two lines:

#include <iostream>using namespace std;

There are some alternatives to using the second line, but let’s keep things simple for now. (If your compiler doesn’t like these lines, it’s not C++98 compatible, and it will have many other problems with the examples in this book.) That’s all you really must know to make your programs work, but now let’s take a more in-depth look.

C++, like C, uses a preprocessor. This is a program that processes a source file before the main compilation takes place. (Some C++ implementations, as you might recall from Chapter 1, use ...