访问结构变量双指针 [英] Accessing a structure variable double pointer

问题描述

一些代码:

typedef struct _WDF_USB_DEVICE_SELECT_CONFIG_PARAMS { 
ULONG Size;
WdfUsbTargetDeviceSelectConfigType Type;
union {   
     struct {
     PUSB_CONFIGURATION_DESCRIPTOR  ConfigurationDescriptor;
     PUSB_INTERFACE_DESCRIPTOR*  InterfaceDescriptors;
     ULONG NumInterfaceDescriptors;
     } Descriptor;

     struct {
     PURB  Urb;
     } Urb;
   } Types;

} WDF_USB_DEVICE_SELECT_CONFIG_PARAMS,*PWDF_USB_DEVICE_SELECT_CONFIG_PARAMS;WDF_USB_DEVICE_SELECT_CONFIG_PARAMS 参数；

} WDF_USB_DEVICE_SELECT_CONFIG_PARAMS,*PWDF_USB_DEVICE_SELECT_CONFIG_PARAMS; WDF_USB_DEVICE_SELECT_CONFIG_PARAMS params;

typedef struct _USB_INTERFACE_DESCRIPTOR {
UCHAR bLength ;
UCHAR bInterfaceClass ;
UCHAR bInterfaceSubClass ;
} USB_INTERFACE_DESCRIPTOR, *PUSB_INTERFACE_DESCRIPTOR ;

能够通过 -> params.Types.Descriptor.NumInterfaceDescriptors 访问 NumInterfaceDescriptors

Able to acess NumInterfaceDescriptors via -> params.Types.Descriptor.NumInterfaceDescriptors

我想通过 WDF_USB_DEVICE_SELECT_CONFIG_PARAMS 访问 bInterfaceClass.请注意，此结构由库填充，我必须访问它

I want to acess bInterfaceClass via WDF_USB_DEVICE_SELECT_CONFIG_PARAMS . Please note that this structure is filled by the library I have to just access it

推荐答案

看起来你想要的是:

ULONG iface;

for (iface = 0; iface < params.Types.Descriptor.NumInterfaceDescriptors; iface++)
{
    do_something_with(params.Types.Descriptor.InterfaceDescriptors[iface]);
}

..但是你真的应该多花点时间把你的问题说清楚，这样人们就不必猜测你的意思了.

..but you should really put some more time into making your questions clear so that people don't have to guess what you mean.

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