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Turn off laptop monitor and lock the system

, 25 Jul 2008 CPOL
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simple code to replace the win+L hotkey

Introduction

I use the Thinkpad laptop for my research work. Usually, I keep it working in the night for the simulation work. Therefore, when I wake up at the next morning, I can analyze the results immediately. I need to lock the WinXP system and turn off the monitor when I leave the laptop. Then I write this program to help me. It is more convenient to use than the traditional way (Win+L hotkey to lock the system and turn off monitor through power schemes).

Code explanation

The code is very simple.

First, turn off the monitor by using SendMessage function. You can find more introduction about it from this article.

// Turn off monitor
    
Sleep(500); // Eliminate user's interaction for 500 ms
    
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 2);
        

Second, use LockWorkStation function to lock the system.

LockWorkStation(); 

Third, the LockWorkStation function requires Windows Vista, Windows XP, or Windows 2000 Professional. To compile the program successfully, we need to add the following macro in the StdAfx.h.

#define _WIN32_WINNT 0x0500
This program is very simple yet very useful. It keeps your task running on the laptop while turns off the monitor for saving energy and protects the laptop from unauthorized use.

Reference

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Weiwei.Fang
Beihang University
China China
http://sites.google.com/site/fangvv

Comments and Discussions

 
GeneralYou shouldn't broadcast the monitor power message. [modified] PinmemberLeo Davidson26-Jul-08 22:42 

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