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'System & API - How to Toggle Num Lock (in two ways)

'Method 1:

Option Explicit
 
Private Const VER_PLATFORM_WIN32_NT = 2
Private Const VER_PLATFORM_WIN32_WINDOWS = 1
Private Const VK_NUMLOCK = &H90
Private Const KEYEVENTF_EXTENDEDKEY = &H1
Private Const KEYEVENTF_KEYUP = &H2
 
Private Type OSVERSIONINFO
    dwOSVersionInfoSize As Long
    dwMajorVersion As Long
    dwMinorVersion As Long
    dwBuildNumber As Long
    dwPlatformId As Long
    szCSDVersion As String * 128
End Type
 
Private Declare Function GetVersionEx Lib "kernel32" Alias "GetVersionExA" _
    (lpVersionInformation As OSVERSIONINFO) As Long
Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, _
    ByVal dwFlags As Long, ByVal dwExtraInfo As Long)
Private Declare Function GetKeyboardState Lib "user32" (pbKeyState As Byte) As Long
Private Declare Function SetKeyboardState Lib "user32" (lppbKeyState As Byte) As Long
Private Declare Function GetKeyState Lib "user32" (ByVal nVirtKey As Long) As Integer
 
Public Function NumLockOn() As Boolean
    'This function will tell us whether the capslock is on or off
    Dim iKeyState As Integer
    iKeyState = GetKeyState(vbKeyNumlock)
    NumLockOn = (iKeyState = 1 Or iKeyState = -127)
End Function
 
Public Sub ToggleNumlock(ByVal bTurnOn As Boolean)
    'To turn Numlock on, set bTurnOn to true
    'To turn Numlock off, set bTurnOn to false
    Dim bytKeys(255) As Byte
    Dim bCapsLockOn As Boolean
    'Get status of the 256 virtual keys
    GetKeyboardState bytKeys(0)
    bCapsLockOn = bytKeys(VK_NUMLOCK)
    Dim typOS As OSVERSIONINFO
    If bCapsLockOn <> bTurnOn Then
        If typOS.dwPlatformId = VER_PLATFORM_WIN32_WINDOWS Then  'Win9x
            bytKeys(VK_NUMLOCK) = 1
            SetKeyboardState bytKeys(0)
        Else    'WinNT/2000
            'Simulate Key Press
            keybd_event VK_NUMLOCK, &H45, KEYEVENTF_EXTENDEDKEY Or 0, 0
            'Simulate Key Release
            keybd_event VK_NUMLOCK, &H45, KEYEVENTF_EXTENDEDKEY Or KEYEVENTF_KEYUP, 0
        End If
    End If
End Sub
 
Private Sub Main()
    If Not NumLockOn Then
        If MsgBox("NumLock is OFF. Would you like to turn it on?", vbYesNo + vbQuestion, "NumLock") = vbYes Then
            Call ToggleNumlock(True)
        End If
    Else
        If MsgBox("NumLock is ON. Would you like to turn it off?", vbYesNo + vbQuestion, "NumLock") = vbYes Then
            Call ToggleNumlock(False)
        End If
    End If
End Sub
 
'Method 2:

'This method will change the state of Num lock internally but will not change status on keyboard

Declare Sub GetKeyboardState Lib "user32" (lpKeyState As Any)
Declare Sub SetKeyboardState Lib "user32" (lpKeyState As Any)
Private Const VK_NUMLOCK = &H90
 
Private Sub Main()
    ReDim KeyboardBuffer(256) As Byte
    GetKeyboardState KeyboardBuffer(0)
    If KeyboardBuffer(VK_NUMLOCK) And 1 Then
        KeyboardBuffer(VK_NUMLOCK) = 0
    Else
        KeyboardBuffer(VK_NUMLOCK) = 1
    End If
    SetKeyboardState KeyboardBuffer(0)
End Sub