Re: exporting a struct with an array from a C++ dll to be accessed in C#

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In that case what should my C# definition look like for the
corresponding C++ definition mentioned below?

C++ struct
struct validationResult
{
int micDataValid; //validity of the microphone data
int rWaveValid; //validity of the r Wave
int signalStatusArray[4]; //validity of each of the channel
data
};

Thanks

On Apr 19, 10:31 am, "Ben Voigt" <r...@xxxxxxxxxxxxx> wrote:
"AM" <abhi.me...@xxxxxxxxx> wrote in message

news:1176921541.639424.294870@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I guess i did not copy my code correctly.
Here is what my C# struct looks like

public struct validationResult
{
public int rWaveValid; //validity of the r Wave
public int[] signalStatusArray; //validity of each of the
//channel data
};

Are you suggesting that the the error is caused by my array definition
in C# is dynamic (because of the []), while my C++ array is of size 4?

I am suggesting looking at the documentation for C# fixed-size buffers which
is here:http://msdn2.microsoft.com/en-us/library/zycewsya(VS.80).aspx

A dynamic (.NET) array carries additional stuff with it like length.
Additionally, since .NET arrays are ref class, only a pointer is stored in
the structure. This is totally different from the layout used by the C++
structure definition you gave.



On Apr 18, 2:01 pm, "Ben Voigt" <r...@xxxxxxxxxxxxx> wrote:
"AM" <abhi.me...@xxxxxxxxx> wrote in message

news:1176913299.669034.41320@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hi,
I have a C++ Dll that has a function that is being exported as
shown below

extern "C" __declspec(dllexport) validationResult __stdcall
_validateData(double dataToMat[], int time);

A structure is defined in the header(.h file) as shown below
struct validationResult
{
int rWaveValid; //validity of the WAVE
int signalStatusArray[4]; //validity of each of the channel data -
'causing the problems'
};

I need to call the above method from C# in where i have the following
structure defined
public struct validationResult
{
public int micDataValid; //validity of the microphone data

magically appeared?

public int rWaveValid; //validity of the r Wave
public int[] signalStatusArray; //validity of each of the
channel data

No, that doesn't match. A dynamically resizeable array is not the same
as
an inline array of size 4. Look for the 'fixed' keyword in the C# help.

};

And my function call is as shown
validationResult res = new validationResult();
res.signalStatusArray = new int[4];
res = _validateData(dataToMat, 2);

When the last line is reached i get an exception that says"Method's
type signature is not PInvoke compatible"
What am I doing wrong.

I know the issue is at the array inside the struct, as when I remove
the array from the C++ struct and the C# struct I get the right
response.

Thanks in Advance.
abhi M


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