Beginning Programming All-in-One For Dummies, 2nd Edition

Chapter 4

Making Decisions by Branching

IN THIS CHAPTER

Using the IF-THEN, IF-THEN-ELSE, and IF-THEN-ELSEIF statements

Using multiple Boolean operators

Using the SELECT CASE statement

The simplest program lists commands one after another in a sequence, much like following the steps of a recipe. Follow a recipe step-by-step, and you always create the same dish. If a program lists commands step-by-step, the computer always produces the same result.

In some cases, you may want a program to do the exact same thing over and over again, such as a simple program to display traffic signals. However, for most programs, you want the computer to react to outside data. To make a computer respond in different ways, a program needs to offer two or more choices for the computer to follow.

When you quit a program, the program may ask, “Do you really want to exit?” At this point, the program is giving the computer a choice of two possible actions to take based on your answer.

If you answer Yes, the computer quits the program. If you answer No, the computer keeps running the program.

When a program gives the computer a choice of two or more commands to follow, that's called a branching or decision ...