With Windows 3.1 (win16), the DLL function/procedure names ignore the case.
With Windows 95 (win32), the function/procedure names are case-sensitive.

The SendMessage api definition is shown in various languages/compilers in order to demonstrate the api syntax variations.

In order to improve readability (i.e. to get rid of the horizontal scroll bar), the Declare statements are presented here as folded. Notice that in a program, the entire Declare statement must be on a single line and that Private will be required is some cases. (In VB 6, the line continuation character - space, underscore, return - can be used to fold the Declare statement to multiple lines.)

The Windows API declarations (function prototypes), types, and constants are defined in

  C:\Program Files\Microsoft Visual Studio\Common\
          Tools\Winapi\WIN32API.TXT

Additional help is available in vb4dll.txt (very good). However, I could not find a similar VB 6 file.

Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
    (ByVal hwnd   As Long, ByVal wMsg  As Long, _
     ByVal wParam As Long,      lParam As  Any) As Long

Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
     (ByVal hwnd   As Long, ByVal wMsg  As Long, _
      ByVal wParam As Long,      lParam As Long) As Long

Private Sub Combo1_GotFocus ()
   Const CB_SHOWDROPDOWN = &H14F
   Dim Tmp
   Tmp = SendMessage(Combo1.hWnd, CB_SHOWDROPDOWN, 1, ByVal 0&)
End Sub

Private Declare Function LockWindowUpdate Lib "User32" _
     (ByVal hWnd As Long) As Long

LockWindowUpdate List1.hWnd ' lock the window to prevent redrawing
For x=1 to 500
  List1.AddItem "Item " & CStr(x)
Next x
LockWindowUpdate 0 ' unlock display

You don't have to specify pointers (references), Access automatically converts variables for you. For example, just use String where a null terminated string should be used.

There is no equivalent for the Delphi nil pointer.

There is no mechanism to pass a pointer to a function using MS Access 97. Later versions use the AddressOf operator.

Unfortunately the examples (if you're lucky enough to find them) are in C!

None of the commands appear to be linked to associated examples. However, if you use the navigation buttons, the following clipboard examples (in C) are available.

• Clipboard Viewer
• Pasting Information from the Clipboard
• Copying Information to the Clipboard

Delphi programs access the Windows API by adding either WinTypes and WinProcs or, starting with Delphi 2.0, adding just Windows to the Uses clause.

By default, my Delphi programs have a Uses Windows, therefore I tried (attached to a button)

  OpenClipboard(null);
  CloseClipboard;

The help explicitly says that the OpenClipboard parameter is either a Windows handle or Null. Yea, right. I tried empty parentheses and no parentheses. It wouldn't compile.

However, the following works.

  OpenClipboard(0);     // 0 means no window
  CloseClipboard;

With Delphi 5, from the menu select Help / Window SDK.

  C:\Program Files\Borland\Delphi 2.0\Source\RTL\WIN\Windows.pas

All the parameter types used in the help can be used as is because they are defined in the windows unit.

From Windows.pas

interface
type

  THandle = Integer;  // These types match what is in help
  UINT    = Integer;
  HWND    = Integer;
  WPARAM  = Longint;
  LPARAM  = Longint;
  LRESULT = Longint;

const
  user32   = 'user32.dll';

     // The following was folded to improve readability 
     //   and should work either way
  function SendMessage(hWnd: HWND; Msg: UINT; 
                       wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall; 

implementation
  function SendMessage; external user32 name 'SendMessageA';

LRESULT SendMessage(

    HWND    hwnd,     // handle of destination window
    UINT    uMsg,     // message to send
    WPARAM  wParam,   // first message parameter
    LPARAM  lParam    // second message parameter
   );

I could not find a way to define Windows API calls in a DPR file. Therefore, I defined them in a PAS (unit) file.

Notice that I was searching for the smallest excutable. The programs which used Clipbrd.pas only required me to write one line of code, while the other 3 testcases required 30 lines of code.

Test Case		exe Size		Version		exe Size		Version
Form with Clipbrd.pas		170 K		2.0
Just Clipbrd.pas		165 K		2.0		291 K		5.0
Button on Form		157 K		2.0
Just Windows.pas		14 K		2.0
Just Wins.pas		14 K		2.0		17 K		5.0

  LRESULT SendMessage(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam);

  SendMessage(predoc->hwndRE, EM_SETTARGETDEVICE,
     (WPARAM) predoc->hdcTarget, (LPARAM) xWidth);

URL: http:// cpcug.org / user / clemenzi / technical / Languages / WindowsAPI.htm