Question

Edited……..

sorry Sir I was referring this piece of code from Stephen Toub’s article..

    private static IntPtr SetHook(LowLevelKeyboardProc proc)
    {
        using (Process curProcess = Process.GetCurrentProcess())
        using (ProcessModule curModule = curProcess.MainModule)
        {
            return SetWindowsHookEx(WH_KEYBOARD_LL, proc,
                GetModuleHandle(curModule.ModuleName), 0);
        }
    }

Can some one explain this to me in short...??

Answer 1

In short this code initializes a key logger. The passed in parmeter, proc, is a callback function that will be called on every key press.

The using statement just ensures immediate calls to dispose() on the declared variables (curProcess and curModule) when they leave scope, thus properly releasing resources in a expedient manner rather than waiting for the garbage collector to release them which may take a while.

SetWindowsHookEx is a win32 api call that allows you to register a callback to be called when a specific OS level event occurs. In this case the first parameter, WH_KEYBOARD_LL, specifies that you would like to register for low level keyboard events. The second parameter is the callback (a Delegate in .Net) that will be called. The third parameter is a windows handle (a pointer managed by the OS) to the module where the callback is located, in this case the main .exe for the process. Note that a process has multiple modules (exe’s or dll’s) loaded at any given time. The last parameter is the thread id that you would like to monitor; because 0 is passed in, the callback will be called for any key events for any window opened on the OS.

More info here about SetWindowsHookEx