Datasheet

Chapter 1: A Quick Introduction to Programming

3. What happens if the user does (as you expect) type something into the input box? Well, this is

where the next line comes in.

Else

You can actually begin to read the code and in fact doing this helps it to make sense. What the

whole loop actually means is that if the value of variable

YourName is a zero-length string, then

assign the variable

Greeting with one value; however, if it contains something else, do some-

thing else (assign

Greeting a different value). This doesn’t protect your script from users enter-

ing data like numbers of non-alphabet characters into the test box, although you could code for

all these conditions if you wanted to.

4. The final line of the code uses the MsgBox function to display the value of the variable

Greeting . Notice that both lines of code assign a value to the Greeting variable. However,

only one of these lines will actually execute in any one running of the script. This is because the

If...Else...End If block makes an either/or decision. Either a given condition is True , or

it is

False . There’s no way it can be neither (not a string that contains text nor a zero-length

string) or both (a zero-length string that contains text). If it is

True , then the script engine will

execute the code between the

If and Else statements. If it is False , then it will execute the code

between the

Else and End If statements.

So, what the complete script does is test the input, and then executes different code, depending on the

result of that test, and hence the term branching. Using this technique allows your script to adapt to the

unpredictable nature of the input. Compare the intelligent script to the following one, which looks pretty

lame.

Dim YourName

Dim Greeting

YourName = InputBox(“Hello! What is your name?”)

Greeting = “Hello, “& YourName & “, great to meet you.”

MsgBox Greeting

This script is just plain dumb because it does not contain any branching logic to test the input; so when

the user does something unpredictable, such as clicking the

Cancel button, or not entering any name at

all, the script does not have the ability to adapt. Compare this to your intelligent script, which is capable

of adapting to the unpredictability of input by testing it with

If...Else...End If branching.

Figure 1-6

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