How to Determine If a VB App is Running Under Windows NT 3.x

There are some scenarios in which your program should behave differently when running under Windows NT version 3.x instead of under Windows version 3.x. For example, an application based on Windows NT needs to handle networking API calls differently. Therefore it is important to find out whether or not your Visual Basic program is running under Windows NT. This article shows you how.

A call to the Windows API GetWinFlags function returns a 32-bit value representing the current system status. By performing a binary AND on this flag with the hexadecimal value &h4000, you can determine whether the underlying operating system is Windows NT version 3.x or not.

Step-by-Step Example

1. Start a new project in Visual Basic. Form1 is created by default.
2. Place a command button (Command1) on Form1.
3. Add the following code to the general declarations section of Form1:

      Const WF_WINNT = &H4000&
      Declare Function GetWinFlags Lib "KERNEL" () As Long
   
      Function IsWindowsNT() As Integer
         IsWindowsNT = (GetWinFlags() And WF_WINNT)
      End Function
   						

4. Add the following code to the Command1 Click event procedure:

      Sub Command1_Click()
         If IsWindowsNT() Then
            MsgBox "You are running under Windows NT"
         Else
            MsgBox "You are running under Windows version 3.x"
         End If
      End Sub
   						

5. Test the program by running it and clicking the command button.