Com Interop (Passing array from C#)

Asked Aug 22 '13 at 23:12

Active Aug 22 '13 at 23:12

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I am new to C# and I am trying this COM Interop with out adding a reference. (Interop Assembly)

I have a C++ COM class which calculates an average like this..

CoClass Function

[id(2)] HRESULT Average([in, size_is(count)] LONG* Array, [in] LONG count, [out,retval] LONG* pResult);

C# Code

From C# I am trying to call this function as following, but I am getting an exception when I try to call this like below. Note : All other functions in that CoClass is working fine from C#. Only when array comes its throwing exception.

[Guid("FA282FAC-A5EE-4A43-AF0B-FB150576DF75"), InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]

public interface ICalc
{

    int Average([MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] long[] values, int count);

}

long[] values = { 1, 2, 3, 4, 5 };
long ret1 = refToCalc.Average1(values,5);

Thanks, John

asked Aug 22 '13 at 23:12

DevMonk

You got the return type correct but not the argument. LONG == int. – Hans Passant Aug 22 '13 at 23:35
I tried both int and long, but I am getting exception "DISP_E_TYPEMISMATCH" – DevMonk Aug 23 '13 at 03:23
That's an error you can only get when using late binding. That can never work, the array is not a SAFEARRAY. You'll need to early-bind, don't use the dynamic keyword. – Hans Passant Aug 23 '13 at 03:33
1

SafeArray solved the problem. Thanks ! – DevMonk Aug 23 '13 at 16:04

Com Interop (Passing array from C#)

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