Microsoft WSH and VBScript Programming for the Absolute Beginner Part 20 doc

Using these statements, you can establish loops within your scripts to let the user iteratively enter as much data as needed, to process the contents of array, to read the content’s file

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“**” & space(46) & “*” & vbCrLf & “ ******************” & _

space(20) & “*************************” & vbCrLf & space(31) & _

“******” & space(26) & “***” & vbCrLf & _

space(34) & “******” & space(22) & “***” & vbCrLf & _

space(37) & “******” & space(17) & “***” & vbCrLf & _

space(26) & “ ****************************” & vbCrLf & _

space(26) & “*******************************” & vbCrLf & _

space(26) & “******************************” & vbCrLf & _

space(26) & “ ****************************” & vbCrLf & vbCrLf & vbCrLf &_ space(10) & “Would you like to boldly go where no one has gone before?”

intPlayGame = MsgBox(strSplashImage, 36, cTitlebarMsg)

If intPlayGame = 6 Then ‘User elected to play the game

strAnswerOne = InputBox(“What was the Science Officer’s name in the “ & _

“original Star Trek series?”, cTitlebarMsg)

If LCase(strAnswerOne) = “spock” Then

intNumberCorrect = intNumberCorrect + 1

End If

Else ‘User doesn’t want to play

MsgBox “Thank you for taking the Star Trek Quiz © Jerry Ford 2002.” & _ vbCrLf & vbCrLf & “Live long and prosper!”, , cTitlebarMsg

WScript.Quit()

End If

strAnswerTwo = InputBox(“What Star Trek villain appeared in both the “ & _

“original series and a Star Trek movie?”, cTitlebarMsg)

If LCase(strAnswerTwo) = “khan” Then

End If

Microsoft WSH and VBScript Programming for the Absolute Beginner, Second Edition

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strAnswerThree = InputBox(“What was the numeric designation of “ & _

“Voyager’s on-board Borg?”, cTitlebarMsg)

If CStr(strAnswerThree) = “7” Then

ElseIf CStr(strAnswerThree) = “7 of 9” Then

End If

strAnswerFour = InputBox(“Name the only Star Trek character to “ & _

“regularly appear on two series and at least two Star Trek “ & _

“movies?”, cTitlebarMsg)

If LCase(strAnswerFour) = “worf” Then

End If

strAnswerFive = InputBox(“What is the last name of your favorite “ & _

“Captain?”, cTitlebarMsg)

If Len(strAnswerFive) > 3 Then

If Instr(1, “kirkpicardsiscojanewayarcher”, LCase(strAnswerFive), 1) _

<> 0 Then

End If

Select Case intNumberCorrect

Case 5 ‘User got all five answers right

strFederationRank = “Admiral”

Case 4 ‘User got 4 of 5 answers right

strFederationRank = “Captain”

strFederationRank = “Commander”

strFederationRank = “Lieutenant-Commander”

strFederationRank = “Lieutenant”

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Case 0 ‘User did not get any answers right

strFederationRank = “Ensign”

End Select

MsgBox “You answered “ & intNumberCorrect & “ out of 5 correct.” & _

vbCrLf & vbCrLf & “Your Star Fleet rank is : “ & _

strFederationRank, , cTitlebarMsg

Summary

This chapter covered a lot of ground You learned how to use the Ifand Case Select state-ments in a number of different ways Using this new information, you updated the Rock,

Paper, and Scissors game and created the Star Trek Quiz game In addition, you learned how

to create VBScripts that could generate reports and log files

CH A L L E N G E S

1 Modify the Star Trek Quiz game so that it asks players for their names and then

use the players’ names at the end of the game to address them according to their ranks

2 Modify the Star Trek Quiz so that it displays the correct answer for any question

that the player misses.

3 Expand the Star Trek Quiz game by adding more questions Store a list of

ques-tions in an array and then use a For Each Next loop to display and process both the questions and the player’s answers

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Processing Collections of Data

6

In this chapter, you’ll learn how to use a number of VBScript statements

that can help you develop scripts capable of processing extremely large amounts of information—in most cases with only a handful of script statements Using these statements, you can establish loops within your scripts

to let the user iteratively enter as much data as needed, to process the contents

of array, to read the content’s files, and to control the execution of VBScript games I’ll also show you how to create shortcuts for your scripts, as well as how

to place them on the Windows desktop, Start Menu, and Quick Launch toolbar Specifically, you will learn how to

• Work with five different types of VBScript loops

• Use loops to control the execution of your scripts (and games)

• Programmatically create Windows shortcuts and use them to configure Windows resources such as the desktop and Start Menu

Project Preview: The Guess a Number Game

In this chapter’s project, you’ll create a script that plays a number guessing game The game generates a random number between 1 and 100, then instructs the player to try to guess it As the player enters guesses, the game provides the player with hints to help him figure out the number If the player types an invalid guess, the game will let him know that only numeric input is accepted

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The player may quit at any time by simply clicking on the Cancel button, or by failing to type

a guess before clicking on OK Once the player guesses the correct answer, the game displays the number of guesses it took him to find the correct answer Figures 6.1 through 6.6 provide

a sneak peek of the game’s interaction

The game uses a VBScript loop to continue executing until either the player guesses the correct answer or quits By developing and working with this game, you will solidify your understand-ing of iterative programmunderstand-ing while also learnunderstand-ing specifically how to apply a loop usunderstand-ing VBScript

Figure 6.1

The Guess a

Number game

begins by

prompting the

player to type a

number between

1 and 100.

Figure 6.2

The game tells

the player to try

again if his or her

guess is too low.

Figure 6.3

The game tells

the player to try

again if his or her

guess is too high.

Figure 6.4

The game

instructs the

player to provide

only numeric

input.

Figure 6.5

The game ends

if the player

clicks on Cancel

or fails to provide

a guess.

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Adding Looping Logic to Scripts

One of VBScript’s best programming features is its strong

support for looping or iterative statements VBScript

provides five different statements that can create

loops Loops provide your scripts with the capability to

process large collections of data using a minimal

num-ber of programming statements that are repeatedly

executed, either for each member of the collection or

for a specified number of times

The following list provides a high-level description of each of VBScript’s looping statements:

• For Next Establishes a loop that iterates for a specified number of times

• For Each Next Establishes a loop that iterates through all the properties associated

with an object

• Do While Establishes a loop that iterates for as long as a stated condition continues

to be true

• Do Until Establishes a loop that iterates until a stated condition finally becomes true.

• While Wend Establishes a loop that iterates for as long as a condition continues

to be true

The For…Next Statement

The For Nextstatement is used to create loops that execute a specific number of times For example, if you’re creating a game requiring the player to enter five guesses, you could use

a For Nextloop to control the logic that supports the data collection portion of the script The syntax for the For Nextstatement is as follows:

For counter = begin To end [Step StepValue]

statements

Once the player

has correctly

guessed the

game’s number,

the player is

congratulated.

Definition

A loop is a collection of statements

repeatedly executed to facilitate the processing of large amounts of data.

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counteris a variable used to control the execution of the loop begin is a numeric value that specifies the starting value of the counter variable end specifies the ending value for the counter variable (that is, the value that, when reached, terminates the loop’s execution)

StepValueis an optional setting that specifies the increment that the For Nextstatement uses when incrementing the value of counter(that is, the value added to counterat the end

of each iteration) If omitted, the value assigned to StepValueis always 1

To better understand the operation of a For Nextloop, look at one example that collects data without using a loop and one that collects the same data using a For Nextloop In the following example, let’s assume that you’re creating a game in which the player is expected to enter the name of his or her five favorite foods You could always handle this type of situation as follows:

Dim strFoodList

strFoodList = “ “

strFoodList = strFoodList & “ “ & InputBox(“Type the name of a food “ & _

“that you really like.”)

MsgBox “You like : “ & strFoodList

As you can see, this example repeats the same statement over and over again to collect user input Then, as proof that it did its job, it displays the data it collected using the MsgBox() function

Collecting five pieces of data like this is a bit of a chore Now imagine a situation in which you want to collect a lot more data Instead of typing the same statement over and over again, as done in the previous example, you can use the For Nextloop

Dim intCounter, strFoodList

For intCounter = 1 To 5

strFoodList = strFoodList & “ “ & InputBox(“Type the name of a “ & _

“food that you really like.”)

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Figure 6.7 demonstrates the output produced by this example

Notice this new script is two lines shorter than the previous example Unlike the previous example, other than the value of the loop’s ending value, this script does not have to be modified to accommodate the collection of additional data For example, to change the For Next loop so that it can accommodate the collection of ten pieces of data, all you’d have to do is modify it like this:

strFoodList = strFoodList & “ “ & InputBox(“Type the name of a “ & _

“food that you really like.”)

Dim intCounter, strFoodList, strNewFood

strNewFood = InputBox(“Type the name of a food that you really like.”)

If strNewFood = “beans” Then

MsgBox “Sorry, but I don’t want to talk to anyone who likes beans!”

Exit For

End If

strFoodList = strFoodList & “ “ & strNewFood

Using a

For Next

loop to collect

and process

user input.

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In this example, the assignment of data has been split into two different statements The first of these statements assigns the name of the food entered by the user to a variable called strNewFood The value of strNewFoodis then added to the list of foods liked by the user only

if it is not “beans,” in which case the script displays a message and then terminates the exe-cution of the For Nextloop As a result, only the foods entered by the user up to the point where beans was typed are displayed

Let’s look at one last example before we examine the other loop statements supported by VBScript In this example, the For Nextstatement’s optional keyword Stephas been added

to change the behavior of the loop

Dim intCounter

For intCounter = 1 To 9 Step 3

WScript.Echo intcounter

In this example, the script will display the value of the counter variable, which is used to control the loop’s execution Instead of counting to 9 by 1s, the script will count by 3s as demonstrated here

C:\>CScript TextScript.vbs

Microsoft (R) Windows Script Host Version 5.1 for Windows

1

4

7

C:\>

The For Each…Next Statement

VBScript’s For Each Nextstatement is a programming tool for working with all the proper-ties associated with objects Every object has a number of properproper-ties associated with it Using the For Each Nextloop, you could write a script to loop through all an object’s properties The syntax of the For Each Nextstatement is as follows:

For Each element In collection

statements

Next [element]

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elementis a variable representing a property associated with the collection(or object) Look

at the following example:

Dim objFsoObject, objFolderName, strMember, strFileList, strTargetFolder

Set objFsoObject = CreateObject(“Scripting.FileSystemObject”)

Set objFolderName = objFsoObject.GetFolder(“C:\Temp”)

For Each strMember in objFolderName.Files

strFileList = strFileList & strMember.name & vbCrLf

This example begins by defining its variables and then establishing an instance of the FileSystemObject It then uses the FileSystemObjectobject’s GetFolder()method to set a ref-erence to a folder Next, using the folder refref-erence, a For Each Nextloop processes all the files (which, in this case, are considered to be properties of the folder) stored within the folder As the For Each Nextloop executes, it builds a list of files stored within the folder and uses the vbCrLfconstant to format the list in an attractive manner The final statement displays the results, as shown in Figure 6.8

For Each Nextloops also are an excellent programming tool for processing the contents

of arrays For example, the following statements are all that are needed to process and dis-play an array called astrGameArray, and to display each of its elements:

For Each intCount In astrGameArray

strMessage = strMessage & intCounter & vbCrLf

To learn more about arrays and see a more complete example of a script that uses the For Each Nextstatement, refer to the Processing Array Contents section in Chapter 4, “Constants, Variables, and Arrays.”

Figure 6.8

Using a For

Each Next

loop to process

the contents of

a folder.

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