RegisterDeviceNotification Question

AnthonyDalton

Hey, im trying to write some C++ code that will monitor when a certain usb device is plugged in/ plugged out. I've been on the MSDN website and good idea of what i need to do. However, I'm having trouble with RegisterDeviceNotification. The RegisterDeviceNotification is always returning NULL. I would very much appreciate if someone could point out where ive gone wrong with this code:


Code:
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <dbt.h>
#include <setupapi.h>

int main()
{
bool result;
HWND hWnd;
char szMsg[80];
GUID InterFaceClassGuid;
void **hDevNotify=NULL;

//CLASSGUID FOR USB DEVICE
InterFaceClassGuid.Data1 = 0x8D948EE9;
InterFaceClassGuid.Data2 = 0xD0AA;
InterFaceClassGuid.Data3 = 0x4A12;
InterFaceClassGuid.Data4[0] = 0x9D;
InterFaceClassGuid.Data4[1] = 0x9A;
InterFaceClassGuid.Data4[2] = 0x9C;
InterFaceClassGuid.Data4[3] = 0xC5;
InterFaceClassGuid.Data4[4] = 0xDE;
InterFaceClassGuid.Data4[5] = 0x36;
InterFaceClassGuid.Data4[6] = 0x19;
InterFaceClassGuid.Data4[7] = 0x9B;

DEV_BROADCAST_DEVICEINTERFACE NotificationFilter;

ZeroMemory( &NotificationFilter, sizeof(NotificationFilter) );
NotificationFilter.dbcc_devicetype= DBT_DEVTYP_DEVICEINTERFACE;
NotificationFilter.dbcc_classguid = InterFaceClassGuid;
hDevNotify=(void**)RegisterDeviceNotification(hWnd,&NotificationFilter, DEVICE_NOTIFY_WINDOW_HANDLE);

if (!hDevNotify)
{
printf("RegisterDeviceNotification failure: %d\n", GetLastError() );
MessageBox(hWnd, szMsg, "ResisterDeviceNotification", MB_OK);

result= false;
}
result= true;


return 0;
}

Thanks

tendofan

Maybe you've left it out of the code you posted, but hWnd doesn't appear to be set to a valid window handle.

Tendofan.

fatherdougalmag

What does GetLastError say? For a start, you'll need to initialise all of the 'size' members of the structures you're using. Although you're using the MSDN example code, it's something to be wary of. Also have a look here for an example of RegisterDeviceNotification.