Guy's Scripting Ezine 46 - MsgBox

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Contents for Guy's Scripting Ezine 46 - MsgBox

• This week's secret
• Example 1 Simple Message Box with one button, OK
• Example 2 Message Box with 3 buttons, Yes, No and Cancel
• Summary

This week’s secret

Early in my scripting career, I thought that MsgBox and WScript.echo were practically one and the same.  Wrong.  Worse still, I used to believe that when it came to generating message boxes, MsgBox was inferior to WScript.echo - wrong again.  Please learn from my mistakes, and open your mind to employing MsgBox, especially in situations where you are dealing with users making choices.

MsgBox

I now realise that in terms of features, MsgBox is superior to WScript.echo.  The first point to note is that unlike WScript.echo,  MsgBox is a function.  The significance is that MsgBox can return a variety of values depending on which dialog button you press.  Therefore, MsgBox opens up exciting possibility for scripting, let us study an example.

Example 1 Simple Message Box with one button, OK.

The purpose of this example is to introduce WMI (Windows Management Interface) which will act as a vehicle for our MsgBox experiments.

Scenario, you want a script to provide information about the operating system.  We can use WMI command to retrieve information about the computer.  For example:
Set objWMIService = GetObject("winmgmts:   While we could write the results to a file, I would prefer to display the WMI information on screen in a message box.

In truth, the MsgBox function is not really needed for our first script.  However, please bear with me, because later examples will be more interesting and complex.  Remember that this example is better than the usual 'Hello World' introductions.

Instructions for MsgBox () Function

1. Copy and paste the script below into notepad.
2. Save the file with .vbs extension e.g. MessageBox.vbs.
3. Double click and examine the message box.

Learning Points

Note 1: There is only a single OK Button!  Later examples will have the additional buttons: 'No' and 'Cancel'.

Note 2:  Numeric 1 is the return value.  So the statement:
If strMbox = 1 Then strMbox = "."  Sets the WMI script to interrogate the local host.  Again this idea of using the return value is to prepare the ground for more complex scripts.

Note 3: The script also employs a loop: For Each .... Next. Collation items such as objItem.Version are properties of the computer, which are extracted by the WMI part of the script.

Example 2 Message Box with 3 buttons, Yes, No and Cancel

Now it's time to build on the first MsgBox example and to dissect the MsgBox() function.

MsgBox(prompt[, buttons][, title])

I will employ the 'Prompt' argument to display text in the Message box.  'Prompt' tells the user what the message box will achieve.

The most interesting MsgBox argument is - 'buttons'.  The default value of 0 (zero) means just displays the OK button.  If we change the value of buttons from 0 to 3 then we get two extra buttons,  'No' and 'Cancel'.

Example A: Buttons is assumed to be 0, the default value.

strMbox = MsgBox("Guy says you must select the LocalHost!")

Example B:  Buttons is explicitly set to 3 (and title is added).

strMbox = MsgBox("Do you want the LocalHost?", 3 ,"Hostname")

When scripting with MsgBox, there are two numbers to be aware of, firstly there is the input or display 'Button' number, which controls the actual Message Box.  Secondly, there is a separate output or return value number which we do not normally see.  However, this return value can be acted upon by subsequent lines of the script.

Naturally, what happens to the output depends on which button you press, this is because unlike WScript.echo,  MsgBox() is a function, and functions return values.  Clicking the Yes button results in a return value of 6.

To give the script some extra beef, I have introduced an Else statement with an Inputbox which fields all return values that are not equal to 6.

Learning Points

Note 1: If strMbox = 6, then WMI processes the LocalHost and returns its operating system data.

Other return values for MsgBox() are 1 = OK,  2 = Cancel,  7 = No.  (And of course, 6 = Yes)

Note 2: If the user clicks NO, or Cancel then strMbox is not 6, so an Inputbox is displayed.

Challenge:  Set the 'Buttons' value to 4.  That should just display Yes and No (Removes the Cancel Button).

Here is the line to edit:
strMbox = MsgBox("Would you like WMI data on LocalHost?",3,"Hostname")

Summary MsgBox

MsgBox is just the ticket for scripts where you need simple user confirmation.  Under the covers, the MsgBox() function supplies a rich set of scripting input and output values.  These return values act as branches for your underlying script.

Guy Thomas recommends Computer Training Software. 

Their topics and material are ideal for getting you started with VBScript.  The videos are easy to follow and you can control the pace.  Try their free demo material and then see if you want to buy the full package. See more about VB Script Training CD.

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