Datasheet

Chapter 1: A Quick Introduction to Programming

All of the examples in this chapter are designed so that you can run them using the Windows Script

Host (WSH). The WSH is a scripting host that allows you to run VBScript programs within Windows.

WSH allows you to try out these example programs for yourself. You may already have WSH installed.

To find out, type the previous example script into a text editor, save the file as

TEST.VBS (it must have

the

.VBS extension, and not a .TXT ), and double-click the file in Windows Explorer. If the script runs,

then you’re all set. If Windows does not recognize the file, then you need to download and install WSH

from

http://msdn2.microsoft.com/en-us/library/ms950396.aspx .

Using Comments

You already know what the first line of code in the previous block does. It declares a variable for use

called

YourName .

The second line in the code is a comment. In VBScript, any text preceded by the single quote character

(

‘ ) is treated as a comment, which means that the VBScript engine completely ignores the text, which

begs the question why bother typing it in at all? It doesn’t contribute to the execution of the script, right?

This is absolutely correct, but don’t forget one of the most important principles of programming: It is not

just computers that may have to read script. It is equally important to write a script with human readers

in mind as it is to write with the computer in mind.

Of course, none of this means you should for one moment forget that when you write scripts, you must

do so with the computer (or, more specifically, the script engine) in mind. If you don’t type the code cor-

rectly (that is, if you don’t use the proper syntax), the script engine won’t be able to execute the script.

However, once you’ve written some useful scripts, you’ll probably need to go back to make some changes

to a script you wrote six months or a year ago. If you didn’t write that code with human readers, as well

as computers, in mind it could be pretty difficult to figure out what you were thinking and how you

decided to solve the problems at the time you wrote the script. Things can get worse. What happens when

you or one of your coworkers has to make some changes to a script you wrote many months ago?

If you did not write that script to be both readable and maintainable, others who use your code will

encounter difficulties deciphering it — no matter how well written the actual computer part of the code is.

Adding comments to your code is just one part of making sure code is clear and readable. There are

many other things that you can do:

❑ Choose clear, meaningful variable names.

❑ Indent code for clarity.

❑ Make effective use of white space.

❑ Organize the code in a logical manner.

All of these aid human-readability and are covered later, but clear, concise comments are by far the most

important. However, too much of a good thing is never good and the same is true for comments. Over-

burdening code with comments doesn’t help. Remember that if you are scripting for the Web that all the

code, including the comments, are downloaded to the browser, so unnecessary comments may adversely

affect download times.

You learn about some good commenting principles later in this chapter, but for now just be aware of the

fact that the comment in line 2 of the script is not really a good comment for everyday use. This is

because, to any semi-experienced programmer, it is all too obvious that what you are doing is declaring

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