各位先進：
小弟初涉USB應用程序，在獲取hub的port口連結信息時遇到麻煩，請各位指教。程序的步驟大致如下：
1.獲取USBHostController的handle
AnsiString strName;
char cstrName[50]={'\0'};
strName=strName.sprintf("\\\\.\\HCD%d",nHC);
strcpy(cstrName,strName.c_str());
CreateFile(cstrName,GENERIC_WRITE,FILE_SHARE_WRITE,NULL,OPEN_EXISTING,0,NULL);
2.獲取roothub的名稱
ULONG nBytes;
USB_ROOT_HUB_NAME hubname ,*phubname;
//First DeviceIoControl is to get root_hub_name 's true length,however ,hubname is only one byte (constrait by USB_ROOT_HUB_NAME type )this time
if(!DeviceIoControlhHostController,IOCTL_USB_GET_ROOT_HUB_NAME,NULL,0,&hubname,sizeof(hubname),&nBytes,NULL))
{
return false;
}
nBytes=hubname.ActualLength;
phubname=(USB_ROOT_HUB_NAME *)malloc(nBytes);
if(!phubname) return false;
//Second DeviceIoControl is to get root_hub_name and put it into memory allocated.
if(DeviceIoControl(hHostController,IOCTL_USB_GET_ROOT_HUB_NAME,NULL,0,phubname,nBytes,&nBytes,NULL))
{
strRH=String(phubname->RootHubName);
free(phubname);
return true;
}
free(phubname);
3.獲取roothub的handle
char cstrHubName[100]={'\0'};
strHubName="\\\\.\\" strHubName;
strcpy(cstrHubName,strHubName.c_str());
CreateFile(cstrHubName,GENERIC_WRITE,FILE_SHARE_WRITE,NULL,OPEN_EXISTING,0,NULL);
4.獲取roothub的port口數
ULONG nBytes;
info->ConnectionIndex=nPort;
DeviceIoControl（hHub,IOCTL_USB_GET_NODE_CONNECTION_INFORMATION,info,nBytes,info,nBytes,&nBytes,NULL);
5.獲取port口的連結信息
ULONG nBytes;
info->ConnectionIndex=nPort;
DeviceIoControl（hHub,IOCTL_USB_GET_NODE_CONNECTION_INFORMATION,info,nBytes,info,nBytes,&nBytes,NULL);


第1-4步都能正確得到結果，但是第五步DeviceIOControl始終返回false，找不到任何連結設備。事實上我的電腦上插著一些USB設備－鍵盤、鼠標、ez usb－fx2開發板等

請各位不吝賜教。

第4與第5是一樣的function? 結果不一樣?

===================引 用 sampuspeng 文 章===================
4.獲取roothub的port口數
ULONG nBytes;
info->ConnectionIndex=nPort;
DeviceIoControl（hHub,IOCTL_USB_GET_NODE_CONNECTION_INFORMATION,info,nBytes,info,nBytes,&nBytes,NULL);
5.獲取port口的連結信息
ULONG nBytes;
info->ConnectionIndex=nPort;
DeviceIoControl（hHub,IOCTL_USB_GET_NODE_CONNECTION_INFORMATION,info,nBytes,info,nBytes,&nBytes,NULL);

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