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Lock workstation

, 6 Jun 2005
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Lock workstation without downloading the Platform SDK.


The LockWorkStation function submits a request to lock the workstation's display. Locking a workstation protects it from unauthorized use.

Code explanation

The following example locks the workstation using the LockWorkStation function. The function requires version Windows 2000 Professional or later.

This example also illustrates load-time dynamic linking. If the DLL is not available, the application using load-time dynamic linking must simply terminate. The run-time dynamic linking example, however, can respond to the error. This is a good way to prevent forced termination. You can use this technique in the applications which should be runnable at all Windows platforms but with delimited functionality following the currently running version of the system.

#include <windows.h>

#define IsWin2000Plus() ((DWORD)(LOBYTE(LOWORD(GetVersion()))) >= 5)

int (__stdcall * MyLockWorkStation)();

int __stdcall WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
                                     LPSTR lpCmdLine, int nCmdShow)
    HINSTANCE hinstLib;

    if (IsWin2000Plus())
        hinstLib = LoadLibrary("USER32.DLL");

        if (hinstLib)
            MyLockWorkStation = (int (__stdcall *)()) 
                  GetProcAddress(hinstLib, "LockWorkStation");

            if (MyLockWorkStation != NULL)
                (MyLockWorkStation) ();

        MessageBox(NULL, "This application requires" 
           " Windows 2000 Professional or higher!", 
           "Lock Workstation", MB_OK);

    return 0;

This application has the same result as pressing Ctrl+Alt+Del and clicking Lock Workstation.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Dalibor Drzik
Web Developer
Slovakia Slovakia
Wink | ;-)

Comments and Discussions

GeneralLogging in PinmemberJAQ224-Feb-07 6:31 
AnswerRe: Logging in PinmemberDalibor Drzik25-Feb-07 0:57 
Questionwin 2K Pinsusslevsky17-Oct-05 6:16 
AnswerRe: win 2K PinmemberDalibor Drzik17-Oct-05 7:54 
NewsRe: win 2K Pinsusslevsky17-Oct-05 8:14 
GeneralAlso known as.. PinmemberAlexander M.6-Jun-05 11:22 
GeneralRe: Also known as.. PinmemberDalibor Drzik7-Jun-05 3:37 
Yes, of course. There are many possibilities. E.g. WinKey + L in Windows XP.
This article (or code example) is an introduction for my next two articles.

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