Chapter 13 Message boxes

13.1 Message box parameters

We have seen that much of the format of a message box can be specified by a single numerical parameter. Here we will review the possible values which can make up this parameter, and illustrate them with a few examples.

First we consider the most basic requirement: the number and type of buttons which should appear. The possible combinations and associated values are listed below.

Constant	Value	Description
vbOKOnly	0	OK button only
vbOKCancel	1	OK and Cancel buttons
vbAbortRetryIgnore	2	Abort, Retry, and Ignore buttons
vbYesNoCancel	3	Yes, No, and Cancel buttons
vbYesNo	4	Yes and No buttons
vbRetryCancel	5	Retry and Cancel buttons

Next we consider the possible icons which can precede the prompt.

Constant	Value	Description
vbCritical	16	Display Critical Message icon
vbQuestion	32	Display Warning Query icon
vbExclamation	48	Display Warning Message icon
vbInformation	64	Display Info Message icon

We can also set which button will be the default response (corresponding to pressing Return).

Constant	Value	Description
vbDefaultButton1	0	First button is default
vbDefaultButton2	256	Second button is default
vbDefaultButton3	512	Third button is default

Finally we can control the behaviour of the message box.

Constant	Value	Description
vbApplicationModal	0	The application stops until the user responds
vbSystemModal	4096	The whole system stops until the user responds
vbMsgBoxHelpButton	16384	A Help button is added to the message box
vbMsgBoxSetForeground	65536	The Message Box is put in the foreground
vbMsgBoxRight	524288	The text in the Message Box is right aligned
vbMsgBoxRtlReading	1048576	The text is presented right to left (for Arabic and Hebrew systems)

To create a custom button setting using the above options, at most one should be chosen from each of the 4 tables. Recall the syntax for the MsgBox command:

MsgBox(prompt[, buttons][, title][, helpfile, context])\xcode}

The value of buttons is given by the above four tables of values. There are various ways in which these can be combined. Suppose for example we wish to display the OK and Cancel buttons, with the Critical Message icon, where the second button is the default. In this case the value of buttons in the MsgBox command could be \[1+16+256\quad\text{or}\quad 273\] or

vbOKCancel + vbCritical + vbDefaultButton2

The latter is probably the most informative, but is also the longest. We could chose to use a new variable to store the value; for example if we defined an integer valued variable called DisplayOptions then we could set

DisplayOptions = vbOKCancel + vbCritical + vbDefaultButton2

and then just use DisplayOptions as the value for buttons in our Message Box.

To illustrate the various icons available, as well as the different types of button references described above, we now give a series of examples. In Figure 13.1 we illustrate the Message Box obtained from the command

MsgBox("This is the Critical Message icon", 2+16, "Example 1")

Figure 13.1: The Critical Message Icon

Figure 13.2 illustrates the result of using

MsgBox("This is the Warning Query icon", 37, "Example 2")

Figure 13.2: The Warning Query Icon

Figure 13.3 illustrates the result of using

MsgBox("This is the Warning Message icon", vbOKOnly + vbExclamation, "Example 3")

Figure 13.3: The Warning Message Icon

Figure illustrates the result of using

MsgBox("This is the Info Message icon", DispVar, "Example 4")

where DispVar = vbYesNo + vbInformation + vbDefaultButton1.

Figure 13.4: The Info Message Icon

If no icon value is chosen then no icon is displayed.

Recall from the lectures that the value of the variable assigned to the MsgBox statement depends on the button pressed by the user. This is an integer valued variable; the possible values (and their names as VBA constants) are given below.

Constant	Return Value	Selected button
vbOK	1	OK
vbCancel	2	Cancel
vbAbort	3	Abort
vbRetry	4	Retry
vbIgnore	5	Ignore
vbYes	6	Yes
`vbNo	7	No

We end with a short example to illustrate the use of the return values.

Sub MsgBoxEx()
Dim DispVal As Integer
DispVal = vbCancel
Do While DispVal = vbCancel
    DispVal = MsgBox("Would you like some tea?", vbYesNoCancel)
Loop
If DispVal = vbYes Then
    DispVal = MsgBox("Tea not available!", 48)
Else
    DispVal = MsgBox("Goodbye")
End If
End Sub

The above code gives a simple dialogue. It asks if the user wishes to have tea, and provides three buttons: Yes, No, and Cancel. Different messages are displayed depending on whether they choose Yes or No.

You should always make sure that your code can handle unexpected inputs from the user. For Message Boxes this is easy, as they can only press the buttons, but when we allow general inputs later this will be a more important consideration. Here we would naturally assume that the user will choose Yes or No, but the code is written so that if they choose Cancel then the Message Box will simply reappear.