在MSDN Library中有完整的帮助资料。
江海问：
首先感谢你上次给我的帮助，现在问题已经解决了。
最近我正在编写WDM驱动程序，在编程过程中我发现Visual C++ 6的SetupApi.h中声明的函数SetupDiGetClassDevs在MSDN和98DDK帮助文件中都没有使用介绍。希望你在这方面能够给予帮助。
答：我使用的MSDN Library是2000年7月版本，不是VC++ 6.0带的那个版本。在2000年7月版本中有这个函数的详细说明（见后面）。MSDN Library每个季度更新一次，有条件的单位可以向微软的代理商购买（如果通过了MCSD考试，免费赠送一年）。你也可以在微软的站点上搜索一下这个函数，一般都可以找到。
SetupDiGetClassDevs
The SetupDiGetClassDevs function retrieves a device information set that contains all devices of a specified class.
To retrieve a device information set for devices on a remote computer, call theSetupDiGetClassDevsEx function.
HDEVINFO SetupDiGetClassDevs(
CONST LPGUID ClassGuid,
PCTSTR Enumerator,
HWND hwndParent,
DWORD Flags
);
Parameters
- ClassGuid
- [in] An optional pointer to a class GUID for a setup class or an interface class. If the DIGCF_DEVICEINTERFACE flag is set, ClassGuid represents an interface class; otherwise, ClassGuid represents a setup class.
If the DIGCF_ALLCLASSES flag is set, this parameter is ignored and the resulting list contains devices of all installed classes.
- Enumerator
- [in] An optional pointer to a string that filters the devices that are returned.
If the DIGCF_DEVICEINTERFACE flag is set, this parameter is an optional pointer to a string representing the PnP name of a particular device. This function examines this particular device only to determine whether it exposes any interfaces of the requested interface class.
If the DIGCF_DEVICEINTERFACE flag is not set, this parameter optionally specifies the name of the PnP enumerator for the devices of interest. (The names of system-supplied enumerators appear in the DDK header file Register.h.) This function examines only device instances of this enumerator. If this parameter is NULL, this function retrieves device information for all device instances on the system.
- hwndParent
- [in] Specifies the handle to the top-level window to be used for any user interface relating to the members of this set.
- Flags
- [in] Specifies control options used in building the device information set. This parameter can be one or more of the following values.
| Value |
Meaning |
| DIGCF_ALLCLASSES |
Return a list of installed devices for all classes. If this flag is set, the ClassGuid parameter is ignored. |
| DIGCF_DEVICEINTERFACE |
Return devices that expose interfaces of the interface class specified by ClassGuid. If this flag is not set, ClassGuid specifies a setup class. |
| DIGCF_PRESENT |
Return only devices that are currently present. |
| DIGCF_PROFILE |
Return only devices that are a part of the current hardware profile. |
Return Values
If the function succeeds, the return value is a handle to a device information set containing all installed devices matching the specified parameters.
If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.
Remarks
To destroy the device information set when you have finished, call the SetupDiDestroyDeviceInfoList function.
If DIGCF_DEVICEINTERFACE is set, ClassGuid (if used) must point to a device interface class GUID, and Enumerator (if used) must point to a PnP device name. The device information set returned contains devices that expose interfaces of the requested interface class. Enumerate the interfaces of the devices using the SetupDiEnumDeviceInterfaces function.
If DIGCF_DEVICEINTERFACE is not set, ClassGuid (if used) must point to a setup class GUID, and Enumerator (if used) must specify the name of the PnP enumerator that enumerates the devices of interest.
To retrieve the devices for a class on a remote computer, call the SetupDiGetClassDevsEx function.
Requirements
Windows NT/2000: Requires Windows 2000.
Windows 95/98: Requires Windows 98.
Header: Declared in Setupapi.h.
Library: Use Setupapi.lib.
江海: 
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