Chapter 4 made a significant improvement in library use by taking all the scattered components of a typical C library and encapsulating them into a structure (an abstract data type, called a class from now on).This not only provides a single unified point of entry into a library component, but it also hides the names of the functions within the class name. In Chapter 5, access control (implementation hiding) was introduced. This gives the class designer a way to establish clear boundaries for determining what the client programmer is allowed to manipulate and what is off limits. It means the internal mechanisms of a data type’s operation are under the control and discretion of the class designer, and it’s clear to client programmers what members they can and should pay attention to.

C++ is a productivity enhancement tool. Why else would you make the effort (and it is an effort, regardless of how easy we attempt to make the transition) to switch from some language that you already know and are productive with to a new language in which you’re going to be less productive for a while, until you get the hang of it? It’s because you’ve become convinced that you’re going to get big gains by using this new tool.

Productivity, in computer programming terms, means that fewer people can make much more complex and impressive programs in less time. There are certainly other issues when it comes to choosing a language, such as efficiency (does the nature of the language cause slowdown and code bloat?), safety (does the language help you ensure that your program will always do what you plan, and handle errors gracefully?), and maintenance (does the language help you create code that is easy to understand, modify, and extend?). These are certainly important factors that will be examined in this book.

But raw productivity means a program that formerly took three of you a week to write now takes one of you a day or two. This touches several levels of economics. You’re happy because you get the rush of power that comes from building something, your client (or boss) is happy because products are produced faster and with fewer people, and the customers are happy because they get products more cheaply. The only way to get massive increases in productivity is to leverage off other people’s code. That is, to use libraries.

A library is simply a bunch of code that someone else has written and packaged together. Often, the most minimal package is a file with an extension like lib and one or more header files to tell your compiler what’s in the library. The linker knows how to search through the library file and extract the appropriate compiled code. But that’s only one way to deliver a library. On platforms that span many architectures, such as Linux/Unix, often the only sensible way to deliver a library is with source code, so it can be reconfigured and recompiled on the new target.

This section covers all the operators in C and C++.

All operators produce a value from their operands. This value is produced without modifying the operands, except with the assignment, increment, and decrement operators. Modifying an operand is called a side effect. The most common use for operators that modify their operands is to generate the side effect, but you should keep in mind that the value produced is available for your use just as in operators without side effects.

                    If you’ve never seen C before, this chapter will give you a decent background in the style of C used in C++. If you are familiar with the style of C described in the first edition of Kernighan & Ritchie (often called K&R C), you will find some new and different features in C++ as well as in Standard C. If you are familiar with Standard C, you should skim through this chapter looking for features that are particular to C++. Note that there are some fundamental C++ features introduced here, which are basic ideas that are akin to the features in C or often modifications to the way that C does things. The more sophisticated C++ features will not be introduced until later chapters.