Chapter 3. Style

There is no programming language, no matter how structured, that will prevent programmers from writing bad programs.

—L. Flon

It is the nobility of their style which will make our writers of 1840 unreadable forty years from now.

—Stendhal

This chapter discusses how to use good programming style to create a simple, easy-to-read program. It may seem backward to discuss style before you know how to program, but style is the most important part of programming. Style is what separates the gems from the junk. It is what separates the programming artist from the butcher. You must learn good programming style first, before typing in your first line of code, so everything you write will be of the highest quality.

Contrary to popular belief, programmers do not spend most of their time writing programs. Far more time is spent maintaining, upgrading, and debugging existing code than is ever spent on creating new work. The amount of time spent on maintenance is skyrocketing. From 1980 to 1990 the average number of lines in a typical application went from 23,000 to 1.2 million. The average system age has gone from 4.75 to 9.4 years.

Most software is built on existing software. I recently completed coding for 12 new programs. Only one of these was created from scratch; the other 11 are adaptations of existing programs.

Programmers believe that the purpose of a program is only to present the computer with a compact set of instructions. This is not true. Programs written only for the machine have two problems:

• They are difficult to correct because sometimes even the author does not understand them.

• Modifications and upgrades are difficult to make because the maintenance programmer must spend a considerable amount of time figuring out what the program does from its code.