In Windows Vista and later versions of Windows, the DEVPROP_TYPE_NULL identifier represents a special base-data-type identifier that indicates that a device property exists. However, that the property has no value that is associated with the property.
Use this base-property-type identifier with the device property functions to delete the value that is associated with a device property.
If a device property function returns this base data type, the property exists, but the property has no value that is associated with it.
Setting a Property of this Type
To set a property whose data type is DEVPROP_TYPE_NULL, call the corresponding SetupDiSet*Xxx* property function and set the function parameters as follows:
Set the PropertyType parameter to DEVPROP_TYPE_NULL, the PropertyBuffer parameter to NULL, and the PropertyBufferSize parameter to zero.
Set the other function input parameters as appropriate to set the property.
Retrieving a Property of this Type
A call to a SetupDiGet*Xxx* property function that attempts to retrieve a device property that has no value will succeed and set the *PropertyType parameter to DEVPROP_TYPE_NULL.
|Devpropdef.h (include Devpropdef.h)|