About <b>FindFirstChangeNotification</b> and <b>ReadDirectoryChangeW</b>

[a_du]

hi, i am developing a folder watching application. i want to use the fuction FindFirstChangeNotification and ReadDirectoryChangeW. The problem here is when i create a MFC project using Dialog approach i inlcude the sample code MSDN provide in a button handler function, and if i run it, the application will hung and i have to use task manager to close it. the same thing happen if i use ReadDirectoryChangeW. however if i put the same code in a win32 application project( using MFC shared .dll ), it can works well. Pls help, thanks, the msdn sample code is below: DWORD dwWaitStatus; HANDLE dwChangeHandles[2]; // Watch the C:\WINDOWS directory for file creation and // deletion. dwChangeHandles[0] = FindFirstChangeNotification( "C:\\WINDOWS", // directory to watch FALSE, // do not watch the subtree FILE_NOTIFY_CHANGE_FILE_NAME); // watch file name changes if (dwChangeHandles[0] == INVALID_HANDLE_VALUE) ExitProcess(GetLastError()); // Watch the C:\ subtree for directory creation and // deletion. dwChangeHandles[1] = FindFirstChangeNotification( "C:\\", // directory to watch TRUE, // watch the subtree FILE_NOTIFY_CHANGE_DIR_NAME); // watch dir. name changes if (dwChangeHandles[1] == INVALID_HANDLE_VALUE) ExitProcess(GetLastError()); // Change notification is set. Now wait on both notification // handles and refresh accordingly. while (TRUE) { // Wait for notification. dwWaitStatus = WaitForMultipleObjects(2, dwChangeHandles, FALSE, INFINITE); switch (dwWaitStatus) { case WAIT_OBJECT_0: // A file was created or deleted in C:\WINDOWS. // Refresh this directory and restart the // change notification. RefreshDirectory is an // application-defined function. RefreshDirectory("C:\\WINDOWS") if ( FindNextChangeNotification( dwChangeHandles[0]) == FALSE ) ExitProcess(GetLastError()); break; case WAIT_OBJECT_0 + 1: // A directory was created or deleted in C:\. // Refresh the directory tree and restart the // change notification. RefreshTree is an // application-defined function. RefreshTree("C:\\"); if (FindNextChangeNotification( dwChangeHandles[1]) == F

[ThatsAlok]

a_du wrote: dwWaitStatus = WaitForMultipleObjects(2, dwChangeHandles, FALSE, INFINITE); Actaully this is BLOCKING CALL,this will block all Message Coming to your Dialog Box. Only Solution to above problem is to create multithread Program!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta

[a_du]

Thanx alot. I have solved that problem by using multithread. BTW, can some one tell me the differences between these two functions and whether it is possible to retrieve file name informations from the FindFirstChangeNotification approach.

[S Senthil Kumar]

As Alok said, you're blocking the UI thread and waiting for directory changes. You need to move that code to a separate worker thread and inform the UI when you get modifications. Regards Senthil _____________________________ My Blog | My Articles | WinMacro

[ThatsAlok]

a_du wrote: it is possible to retrieve file name informations from the FindFirstChangeNotification approach. Nope, It not Possible to Retrieve File Information using FindFirstChangeNotification approach!, only ReadDirectoryChangeW will help in this regard!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta

[ThatsAlok]

S. Senthil Kumar wrote: and inform the UI when you get modifications. Oops, I forget to mention that, Thanks for correcting me! :)

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta