下面的程式片段會切換 CapsLock, NumLock 及 ScrollLock 的鍵盤狀態

BCB

  // KeyState 是一個 256 bytes 的鍵盤狀態陣列, 每個元素其值為 0 或 1        
  PBYTE KeyState = new BYTE [256];

  GetKeyboardState(KeyState);
  KeyState[VK_CAPITAL] = !KeyState[VK_CAPITAL];
  KeyState[VK_NUMLOCK] = !KeyState[VK_NUMLOCK];
  KeyState[VK_SCROLL] = !KeyState[VK_SCROLL];
  SetKeyboardState(KeyState);

DELPHI

//設定鍵盤燈號並傳回上次的值
function KeyLockOn(nVirtKey: Integer; 
                    bLockIt: Boolean): Boolean;
var
  KeyState: TKeyboardState;
begin
  if not GetKeyboardState(KeyState) then
    exit;
  Result := (KeyState[nVirtKey] = 1);
  if bLockIt then
    KeyState[nVirtKey] := 1
  else
    KeyState[nVirtKey] := 0;
  SetKeyboardState(KeyState);
end;
 
// 設定 Insert 狀態並傳回上次的設定值
function InsLock(bLockIt: boolean): Boolean;
begin
  Result := KeyLockOn(VK_INSERT, bLockIt);
end;


// 設定 CapsLock 並傳回上次的設定值
function CapsLock(bLockIt: boolean): Boolean;
begin
  Result := KeyLockOn(VK_CAPITAL, bLockIt);
end;

// 設定 NumLock 並傳回上次的設定值
function NumLock(bLockIt: boolean): Boolean;
begin
  Result := KeyLockOn(VK_NUMLOCK, bLockIt);
end;

// 設定 ScrollLock 並傳回上次的設定值
function ScrollLock(bLockIt: boolean): Boolean;
begin
  Result := KeyLockOn(VK_SCROLL, bLockIt);
end;