GUsb.Device.get_custom_index

### Method

# GUsb Deviceget_custom_index

#### Declaration

    guint8
    g_usb_device_get_custom_index (
      GUsbDevice* self,
      guint8 class_id,
      guint8 subclass_id,
      guint8 protocol_id,
      GError** error
    )

#### Description

Gets the string index from the vendor class interface descriptor.

Available since: | 0.2.5

#### Parameters

`class_id` | `guint8`
| A device class, e.g. 0xff for VENDOR.
`subclass_id` | `guint8`
| A device subclass.
`protocol_id` | `guint8`
| A protocol number.
`error` | `GError **`
| The return location for a `GError*`, or `NULL`.

#### Return value

Returns: | `guint8`
| A non-zero index, or 0x00 for failure.