By reading this chapter first, you’ll get the basic flavor of what it is like to program with objects in C++, and you’ll also discover some of the reasons for the enthusiasm surrounding this language. This should be enough to carry you through Chapter 3, which can be a bit exhausting since it contains most of the details of the C language.

The user-defined data type, or class, is what distinguishes C++ from traditional procedural languages. A class is a new data type that you or someone else creates to solve a particular kind of problem. Once a class is created, anyone can use it without knowing the specifics of how it works, or even how classes are built. This chapter treats classes as if they are just another built-in data type available for use in programs.

Classes that someone else has created are typically packaged into a library. This chapter uses several of the class libraries that come with all C++ implementations. An especially important standard library is iostreams, which (among other things) allow you to read from files and the keyboard, and to write to files and the display. You’ll also see the very handy string class, and the vector container from the Standard C++ Library. By the end of the chapter, you’ll see how easy it is to use a pre-defined library of classes.

In order to create your first program you must understand the tools used to build applications.