Re: SetupDiGetClassDevs and DIGCF_PRESENT

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#268

From: Bob Gonder
Date: Thu, 15 May 2008 16:50

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JohnG wrote:

>In sample code below SetupDiGetClassDevs always returns 
>INVALID_HANDLE_VALUE. GetLastError() returns 87, which I 
>believe is incorrect parameter. If I replace DIGCF_PRESENT  
>with DIGCF_PRESENT | DIGCF_ALLCLASSES, the code works however 
>when I enumerate the hardware I get much more then just the 
>hardware that is currently in the system. Any ideas why I cant 
>use only the DIGCF_PRESENT flag? I am trying to query only the 
>hardware that is in the system.

Read the comment section in the docs here:
http://msdn.microsoft.com/en-us/library/ms792959.aspx

You must either specify a device guid in ClassGuid,
or use DIGCF_ALLCLASSES. So, your use of NULL for
ClassGuid was in fact an incorrect parameter.

See also example code here
http://support.microsoft.com/kb/259695

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Subject: Re: SetupDiGetClassDevs and DIGCF_PRESENT
Date: Thu, 15 May 2008 09:50:12 -0700
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