Help with a Declare (pointer to a pointer)

[Sean Woods]

I have a function that I am trying to write a Declare for in VB. Any help
on it would be appreciated.

The C function looks like this:
WINCRYPT32API HCERTSTORE WINAPI CertOpenStore(
IN LPCSTR lpszStoreProvider, IN DWORD dwEncodingType,
IN HCRYPTPROV hCryptProv, IN DWORD dwFlags, IN const void *pvPara);

What I have got for the VB delcare is:
Public Declare Function CertOpenStore Lib "crypt32.dll"

ByVal lpszStoreProvider As String, ByVal dwMsgAndCertEncodingType As
Long,
ByVal hCyrptProv As Long, ByVal dwFlags As Long, ByVal pvPara As Long)
As Long

I think this is close but that last parameter maybe wrong because it appears
to be a pointer to a pointer.

The next question... How do I actually use that declare. Again it is the
last parameter that gives me problems? In particular what I need to pass in
is a unicode string, or a reference to one rather, but later it could be
something else later.

Any help would be very much appreciated.

Thanks
Sean Woods

[Mattias Sjögren]

Sean,

>What I have got for the VB delcare is:
>Public Declare Function CertOpenStore Lib "crypt32.dll"
>
> ByVal lpszStoreProvider As String, ByVal dwMsgAndCertEncodingType As
>Long,
> ByVal hCyrptProv As Long, ByVal dwFlags As Long, ByVal pvPara As Long)
>As Long

>I think this is close

It looks like it should work. You could also declare the the last
parameter As Any if you ever need to pass something else to it.


>but that last parameter maybe wrong because it appears
>to be a pointer to a pointer.

No, it's a simple one-level pointer, that can point to anything.


>The next question... How do I actually use that declare. Again it is the
>last parameter that gives me problems? In particular what I need to pass in
>is a unicode string, or a reference to one rather, but later it could be
>something else later.

For Unicode strings, pass it StrPtr(YourString)


Mattias

===
Mattias Sjögren (VB MVP)
mattias @ mvps.org
http://www.msjogren.net/dotnet/

[Mattias Sjögren]

Sean,

>What I have got for the VB delcare is:
>Public Declare Function CertOpenStore Lib "crypt32.dll"
>
> ByVal lpszStoreProvider As String, ByVal dwMsgAndCertEncodingType As
>Long,
> ByVal hCyrptProv As Long, ByVal dwFlags As Long, ByVal pvPara As Long)
>As Long

>I think this is close

It looks like it should work. You could also declare the the last
parameter As Any if you ever need to pass something else to it.


>but that last parameter maybe wrong because it appears
>to be a pointer to a pointer.

No, it's a simple one-level pointer, that can point to anything.


>The next question... How do I actually use that declare. Again it is the
>last parameter that gives me problems? In particular what I need to pass in
>is a unicode string, or a reference to one rather, but later it could be
>something else later.

For Unicode strings, pass it StrPtr(YourString)


Mattias

===
Mattias Sjögren (VB MVP)
mattias @ mvps.org
http://www.msjogren.net/dotnet/

[Sean Woods]

Mattias,

Thanks... that did the trick. I always forget about StrPtr, VarPtr, and
ObjPtr.

Sean


"Mattias Sjögren" <mattias.dont.want.spam@mvps.org> wrote in message
news:3c0fd0da$1@147.208.176.211...
> Sean,
>
> >What I have got for the VB delcare is:
> >Public Declare Function CertOpenStore Lib "crypt32.dll"
> >
> > ByVal lpszStoreProvider As String, ByVal dwMsgAndCertEncodingType As
> >Long,
> > ByVal hCyrptProv As Long, ByVal dwFlags As Long, ByVal pvPara As
Long)
> >As Long
>
> >I think this is close
>
> It looks like it should work. You could also declare the the last
> parameter As Any if you ever need to pass something else to it.
>
>
> >but that last parameter maybe wrong because it appears
> >to be a pointer to a pointer.
>
> No, it's a simple one-level pointer, that can point to anything.
>
>
> >The next question... How do I actually use that declare. Again it is the
> >last parameter that gives me problems? In particular what I need to pass
in
> >is a unicode string, or a reference to one rather, but later it could be
> >something else later.
>
> For Unicode strings, pass it StrPtr(YourString)
>
>
> Mattias
>
> ===
> Mattias Sjögren (VB MVP)
> mattias @ mvps.org
> http://www.msjogren.net/dotnet/

[Sean Woods]

Mattias,

Thanks... that did the trick. I always forget about StrPtr, VarPtr, and
ObjPtr.

Sean


"Mattias Sjögren" <mattias.dont.want.spam@mvps.org> wrote in message
news:3c0fd0da$1@147.208.176.211...
> Sean,
>
> >What I have got for the VB delcare is:
> >Public Declare Function CertOpenStore Lib "crypt32.dll"
> >
> > ByVal lpszStoreProvider As String, ByVal dwMsgAndCertEncodingType As
> >Long,
> > ByVal hCyrptProv As Long, ByVal dwFlags As Long, ByVal pvPara As
Long)
> >As Long
>
> >I think this is close
>
> It looks like it should work. You could also declare the the last
> parameter As Any if you ever need to pass something else to it.
>
>
> >but that last parameter maybe wrong because it appears
> >to be a pointer to a pointer.
>
> No, it's a simple one-level pointer, that can point to anything.
>
>
> >The next question... How do I actually use that declare. Again it is the
> >last parameter that gives me problems? In particular what I need to pass
in
> >is a unicode string, or a reference to one rather, but later it could be
> >something else later.
>
> For Unicode strings, pass it StrPtr(YourString)
>
>
> Mattias
>
> ===
> Mattias Sjögren (VB MVP)
> mattias @ mvps.org
> http://www.msjogren.net/dotnet/