Programming Excel with VBA and .NET : Tasks in Visual Basic - Interact with Users

1. Types of Tasks

You can perform several broad categories of tasks with the Visual Basic language. Since we're talking about Visual Basic (not Excel), these tasks tend to be very general. More specific tasks are usually handled through Excel objects.

2. Interact with Users

Visual Basic provides two simple ways to interact with users:

• Use InputBox to get text input.

• Use MsgBox to display short messages and get button-click responses.

I've already used InputBox and MsgBox a number of times in previous examples, but one more sample won't hurt:

    Sub MsgBoxInputBox( )
        Dim str As String, val As VbMsgBoxResult
        ' InputBox gets simple text input.
        str = InputBox("Enter some text.", "Chapter 3", "Some text")
        ' Use If to test if a value was entered.
        If str <> "" Then
            ' You can combine style constants in MsgBox.
            val = MsgBox(str, vbQuestion + vbOKCancel, "Chapter 3")
            ' Return value indicates which button was clicked.
            If val = vbOK Then Debug.Print "OK" Else Debug.Print "Cancel"
        End If
    End Sub

The preceding code displays a simple dialog box to get text, then displays the text in another simple dialog box, as shown in Figure 1.

The MsgBox function can display many different styles and buttons, depending on the Button argument setting. All of the VbMsgBoxStyle settings are listed in Table 2.

Figure 1. InputBox and MsgBox functions display simple dialog boxes

Compatible settings in Table 2 can be combined using addition. For instance, you can combine button, icon, and default settings in a single message box as shown here:

    val = MsgBox("Unable to continue.", _
      vbCritical + vbAbortRetryIgnore + vbDefaultButton2, "Error")

The value returned by MsgBox is a VbMsgBoxResult constant that indicates which button the user clicked. Typically, you compare that result to the button constants listed in Table 2 in an If or Select statement:

    If val = VbMsgBoxResult.vbAbort Then ...

If you are displaying a dialog with only a single OK button, you probably don't care about the value returned by MsgBox. In that case, you can omit the parentheses:

    MsgBox "The answer is " & val, , "Chapter 3"

In addition to Visual Basic's built-in InputBox and MsgBox functions, there are several other ways to display much more complex dialog boxes and data-entry forms from Excel (see Table 3).