Practical C++ Programming, 2nd Edition

Chapter 23. Modular Programming

Many hands make light work.

—John Heywood

So far, we have been dealing with small programs. As programs grow larger and larger, they should be split into sections, or modules. C++ allows programs to be split into multiple files, compiled separately, and then combined (linked) to form a single program.

In this chapter, we go through a programming example, discussing the C++ techniques needed to create good modules. You also are shown how to use make to put these modules together to form a program.

Modules

A module is a collection of functions or classes that perform related functions. For example, there could be a module to handle database functions such as lookup, enter, and sort. Another module could handle complex numbers, and so on.

Also, as programming problems get big, more and more programmers are needed to finish them. An efficient way of splitting up a large project is to assign each programmer a different module. That way each programmer only has to worry about the internal details of her own code.

In this chapter, we discuss a module to handle infinite arrays. The functions in this package allow the user to store data in an array without worrying about the array’s size. The infinite array grows as needed (limited only by the amount of memory in the computer). The infinite array will be used to store data for a histogram, but it can also be used to store things such as line numbers from a cross-reference program or other types of data.

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