Calling Control Panel applets from your programs and scripts

[charleychacko]

Looking for a way to open Control Panel applets from your programs without opening the Control Panel?

Whether you want your users to change the system date/time properties, add a new modem or change joystick settings, there's an easy way to call all such Control Panel applets (icons) without opening the Control Panel folder. The good news is that you can use this method in any Windows programming environment or even in a simple BATch file.

Running the following command from your program will do the trick (CPL being the file name of the Control Panel applet to open. a list of such applets can be found at the bottom of this document):

rundll32.exe shell32.dll,Control_RunDLL CPL

For example, to bring up the "Date/Time Properties" dialog box, run:

rundll32.exe shell32.dll,Control_RunDLL timedate.cpl

To open a Control Panel applet from a Windows BATch file, simply include the above command in a line by itself. Since we're using a regular executable file, rundll32.exe, you can include the above command in any location you can execute a program, such as a shortcut icon, Intranet web page anchor, script, etc.

Although the concept is simple enough, let's look at some code samples on how to ease calling the above command from a C/C++ or Delphi program. Note that you can use any "WinExec()" equivalent function to achieve the same effect.

C Language / C++ / C++Builder code sample

Include the following code in your program and call "RunControlPanelApplet()". Example call: RunControlPanelApplet("timedate.cpl");

#include<stdio.h>
#include<windows.h>

int RunControlPanelApplet(
char*sAppletFileName)
{
char s[1024];

sprintf(s,
  "rundll32.exe shell32.dll,"
  "Control_RunDLL %s",
  sAppletFileName);

return
  WinExec(s, SW_SHOWNORMAL);
}
Listing #1 : C code. Download opencpl2.c (0.31 KB). [ You are not allowed to view links. Register or Login ]

Delphi / C++Builder code sample

Include the following unit into your project and call "RunControlPanelApplet()" with the name of the applet to open. Example: RunControlPanelApplet( 'timedate.cpl' );

unit open_cpl;

interface

function RunControlPanelApplet(
sAppletFileName : string) : integer;

implementation

uses Windows;

function RunControlPanelApplet(
sAppletFileName : string) : integer;
begin
Result :=
WinExec(
  PChar('rundll32.exe shell32.dll,'+
  'Control_RunDLL '+sAppletFileName),
  SW_SHOWNORMAL);
end;

end.
Listing #2 : Delphi code. Download opencpl1.pas (0.33 KB). [ You are not allowed to view links. Register or Login ]

How to find the names of the applet files

Control Panel applet files have the extension CPL. To get a list of applets installed on your system, go to your Windows SYSTEM (Windows 95) or SYSTEM32 (Windows NT) directory and look for files with the CPL extension. Example: DIR C:\WINDOWS\SYSTEM\*.CPL

Following is a list of applets common to Windows 95 and Windows NT:

access.cpl: Accessibility Properties
appwiz.cpl: Add/Remove Programs Properties
desk.cpl: Display Properties
intl.cpl: Regional Settings Properties
joy.cpl: Joystick Properties
main.cpl: Mouse Properties
mmsys.cpl: Multimedia Properties
modem.cpl: Modems Properties
sysdm.cpl: System Properties
timedate.cpl: Time/Date Properties