Calling C++ method in C#

Question

I need to call a c++ function from c#.

c++ function is

BOOL Usb_GetDevicesList(int &iNbDevices, char aszDeviceName[][128]);

I tried

  [DllImport("UsbComm.dll", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.Cdecl)]
        public static extern int Usb_GetDevicesList(int iNbDevices, out byte[][] aszDeviceName);

I got error

Cannot marshal 'parameter #2': There is no marshaling support for nested arrays.

Please help me in converting this c++ function to C#.

See this link http://stackoverflow.com/questions/991383/call-a-c-function-from-c-sharp — husnain_sys, Feb 03 '15 at 06:57
Presumably `iNbDevices` contains the length of the supplied array `aszDeviceName` on entry, and the number of items written to the array on exit? With `FALSE` returned if the supplied array is not long enough. Unless you also explain the semantics of the function it is hard to help. — David Heffernan, Feb 03 '15 at 12:52

score 1 · Accepted Answer · edited May 23 '17 at 12:28

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You can just flatten the 2D array to a single dimensional one and then pass it.

 flattened_array[(y * width) + x] = source[x][y];

Refer to this answer

edited May 23 '17 at 12:28

Community

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answered Feb 03 '15 at 07:00

a_pradhan

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You would need to change the C++ function as well to accept a flattened 2D array. – a_pradhan Feb 03 '15 at 07:06
We cannot change in C++ function – Jayaraj.K Feb 03 '15 at 07:06
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Look into this in that case : http://stackoverflow.com/questions/18705857/marshal-a-c-char-array-to-c-sharp – a_pradhan Feb 03 '15 at 07:10
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@AkashPradhan The C++ function doesn't need to be changed. – David Heffernan Feb 03 '15 at 12:50
^Yes I posted the link where no change in C++ is required. – a_pradhan Feb 03 '15 at 12:59
@Akash Then what is the rest of your answer for? – David Heffernan Feb 03 '15 at 13:38

Calling C++ method in C#

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