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[Page 8 (continued)]

1.9. C++ Standard Library

C++ programs consist of pieces called classes and functions. You can program each piece that you may need to form a C++ program. However, most C++ programmers take advantage of the rich collections of existing classes and functions in the C++ Standard Library. Thus, there are really two parts to learning the C++ "world." The first is learning the C++ language itself; the second is learning how to use the classes and functions in the C++ Standard Library. Throughout the book, we discuss many of these classes and functions. P J. Plauger's book, The Standard C Library (Upper Saddle River, NJ: Prentice Hall PTR, 1992), is a must read for programmers who need a deep understanding of the ANSI C library functions that are included in C++, how to implement them and how to use them to write portable code. The standard class libraries generally are provided by compiler vendors. Many special-purpose class libraries are supplied by independent software vendors.

[Page 9]

Software Engineering Observation 1.1

Use a "building-block" approach to create programs. Avoid reinventing the wheel. Use existing pieces wherever possible. Called software reuse, this practice is central to object-oriented programming.

Software Engineering Observation 1.2

When programming in C++, you typically will use the following building blocks: Classes and functions from the C++ Standard Library, classes and functions you and your colleagues create and classes and functions from various popular third-party libraries.

We include many Software Engineering Observations throughout the book to explain concepts that affect and improve the overall architecture and quality of software systems. We also highlight other kinds of tips, including Good Programming Practices (to help you write programs that are clearer, more understandable, more maintainable and easier to test and debugor remove programming errors), Common Programming Errors (problems to watch out for and avoid), Performance Tips (techniques for writing programs that run faster and use less memory), Portability Tips (techniques to help you write programs that can run, with little or no modification, on a variety of computersthese tips also include general observations about how C++ achieves its high degree of portability) and Error-Prevention Tips (techniques for removing bugs from your programs and, more important, techniques for writing bug-free programs in the first place). Many of these are only guidelines. You will, no doubt, develop your own preferred programming style.

The advantage of creating your own functions and classes is that you will know exactly how they work. You will be able to examine the C++ code. The disadvantage is the time-consuming and complex effort that goes into designing, developing and maintaining new functions and classes that are correct and that operate efficiently.

Performance Tip 1.1

Using C++ Standard Library functions and classes instead of writing your own versions can improve program performance, because they are written carefully to perform efficiently. This technique also shortens program development time.

Portability Tip 1.2

Using C++ Standard Library functions and classes instead of writing your own improves program portability, because they are included in every C++ implementation.

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