Re: [cffi-devel] Passing address of pointer

Hello Frank,

On Thu, Aug 25, 2011 at 6:19 PM, Frank Goenninger frgo@me.com wrote:

In the sample code from Apple the C function is called like this:

typedef struct MyPrivateData {    io_object_t            notification;    IOUSBDeviceInterface   **deviceInterface;    CFStringRef            deviceName;    UInt32                 locationID; } MyPrivateData;

Why is deviceInterface a pointer to a pointer?

IOCFPlugInInterface     **plugInInterface = NULL; SInt32                  score; HRESULT                 res;

res = (*plugInInterface)->QueryInterface( plugInInterface,                                          CFUUIDGetUUIDBytes( kIOUSBDeviceInterfaceID ),                                          (LPVOID*) &privateDataRef->deviceInterface );