Re: PInvoke Marshalling....
- From: "Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 23 Oct 2007 10:34:41 -0400
Daniel,
Yes, if the API function is going to write to the buffer, then passing a
StringBuilder will cause the data to be marshaled back to you correctly.
--
- Nicholas Paldino [.NET/C# MVP]
- mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
"Daniel Bass" <danREMOVEbass@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:%23EkQlBYFIHA.1212@xxxxxxxxxxxxxxxxxxxxxxx
Nicholas,
Excellent, thanks for the prompt reply!
pData is a buffer that I create, then pass into the function to populate.
Does the parameter as a StringBuilder marshall this data correctly?
Thanks.
Dan.
"Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote
in message news:ecx5T6XFIHA.280@xxxxxxxxxxxxxxxxxxxxxxx
Daniel,
Actually, it's not pretty obvious. In C++, long corresponds to a
32-bit integer, which in C#, is an int. Also, you should declare how
your strings are marshaled in the DllImport attribute. All-in-all, your
declaration should look like this:
[DllImport("Dependencies\\SNAPI.DLL", CharSet=CharSet.Ansi)]
public static extern int SNAPI_SetVersionBuffer(IntPtr DeviceHandle,
StringBuilder pData, int max_length);
Also, if the pData parameter is not going to be written to by the API
function, you can pass it as a string.
--
- Nicholas Paldino [.NET/C# MVP]
- mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
"Daniel Bass" <danREMOVEbass@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:u83rn0XFIHA.1056@xxxxxxxxxxxxxxxxxxxxxxx
Greetings!
I'm trying to call this method in a c# app...
SNAPIDLL_API int __stdcall SNAPI_SetCapabilitiesBuffer(HANDLE
DeviceHandle, unsigned char *pData, long max_length);
So far I've got this:
[DllImport("Dependencies\\SNAPI.DLL")]
public static extern int SNAPI_SetVersionBuffer(IntPtr DeviceHandle,
StringBuilder pData, long max_length);
Keep getting a PInvokeStackImbalance error and I think it's the 2nd
paramter pData because I've referenced the device handler and the long
typedef is pretty obvious.
For the 2nd paramter I've tried the following without success:
byte[]
char[]
string
StringBuilder
[MarshalAs(UnmanagedType.AnsiBStr)] string
HELP!
Thanks.
Dan.
.
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