Turn screen off using C windows 8

Question

I want to write a very tiny app using C that would turn the screen off or on. mapping keys to call a specific function should not be difficult.

Which are the system commands to turn the screen off or on on windows?

Thanks

Answer 1

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

// Turn on monitor
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) -1);

// Low power monitor
Sleep(500); // Eliminate user's interaction for 500 ms
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 1);

Note that

**1** - the display is going to low power.
**2** - the display is being shut off.
**-1** - the display is being turned on (undocumented value).