Consult everybody a great god why OnDeviceChange always received 7? Equipment has been registered, no prompt registration failed, why only received 7?

//registered part 
UID guid; 
Retrieves the hr=CoCreateGuid (& amp; Guid); 

//in the notification message dialog initialization process equipment register to the winproc 
//Register to receive notification when a USB device is plugged in. 
HDEVNOTIFY gNotifyDevHandle; 
DEV_BROADCAST_DEVICEINTERFACE broadcastInterface; 
BroadcastInterface. Dbcc_size=sizeof (DEV_BROADCAST_DEVICEINTERFACE); 
BroadcastInterface. Dbcc_devicetype=DBT_DEVTYP_DEVICEINTERFACE; 

Memcpy (& amp; (broadcastInterface. Dbcc_classguid), & amp; (guid), sizeof (struct _GUID)); 

GNotifyDevHandle=RegisterDeviceNotification (this - & gt; GetSafeHwnd (), 
& BroadcastInterface, 
DEVICE_NOTIFY_WINDOW_HANDLE); 
//-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
Afx_msg BOOL OnDeviceChange (UINT nEventType, dwords dwData); 
//-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
BEGIN_MESSAGE_MAP (CRFIDInputToolDlg CDialog) 
ON_WM_DEVICECHANGE () 
. 
END_MESSAGE_MAP () 
//-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
BOOL CRFIDInputToolDlg: : OnDeviceChange (UINT nEventType, dwords dwData) 
{
DwData DEV_BROADCAST_DEVICEINTERFACE * DBD=(DEV_BROADCAST_DEVICEINTERFACE *); 

The switch (nEventType) 
{
Case DBT_DEVICEREMOVECOMPLETE: 
AfxMessageBox (_T (" equipment to remove ")); 
break; 
Case DBT_DEVICEARRIVAL: 
AfxMessageBox (_T (" equipment access ")); 
break; 
Default: 
break; 
} 
} 

Everybody to help me have a look at where is wrong, thank you

CodePudding user response:

DBT_DEVNODES_CHANGED=0 x0007;

CodePudding user response:

Different equipment & amp; Driver may send message is not the same, can be to enumerate the WM_DEVICECHANGE device to determine changes in