1.3 How to Learn C++

The only way to learn how to program is to write programs. You'll learn a lot more by writing and debugging programs than you ever will by reading this book. This book contains many programming exercises, and you should try to do as many of them as possible. When doing the exercises, keep good programming style in mind. Always comment your programs, even if you're doing the exercises only for yourself. Commenting helps you organize your thoughts, and commenting your own programs is good practice for when you go into the "real world."

Don't let yourself be seduced by the idea that, "I'm only writing these programs for myself, so I don't need to comment them." First of all, code that looks obvious to you when you write it can often be confusing and cryptic when you revisit it a week later. Writing comments also helps you organize your ideas. (If you can write out an idea in English, you are halfway to writing it in C++.)

Finally, programs tend to be around far longer than expected. I once wrote a highly system-dependent program that was designed to work only on the computer at Caltech. As I was the only one who would ever use the program, it would print the following message if I got the command line wrong:

?LSTUIT User is a twit

A few years later I was a student at Syracuse University. The chief secretary at the School of Computer Science needed a program similar to my Caltech listing program, so I adapted my program for her use. Unfortunately, I had forgotten about my funny little error message.

Imagine how horrified I was when I came into the Computer Science office and was accosted by the chief secretary. This lady had so much power she could make the dean cringe. She looked at me and said, "User is a twit, huh?" Luckily she had a sense of humor, or I might not be here today.

Sprinkled throughout are not only examples of working programs (to show you how to do things), but also examples of broken programs where we ask you to go through the program and figure out what's wrong. Often the problem is very subtle, such as a misplaced semicolon or use of = instead of ==. These programs let you learn how to spot mistakes in a small program. That way when you make similar mistakes in a big program—and you will make mistakes—you will be trained to spot them.