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How can I list the list <int>?

I have a dll in C ++, it returns a list, I want to use it in my C # application as a list

[DllImport("TaskLib.dll", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
public static extern List<int> GetProcessesID();

public static List<int> GetID()
{
    List<int> processes = GetProcessesID();//It is impossible to pack a "return value": The basic types can not be packed
    //...
}
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2 answers

Per Jared Par:

Usually, generators are not supported in any interaction scenario. Both PInvoke and COM Interop will fail if you try to marshal a common type or value. Therefore, I would expect Marshal.SizeOf to be unverified or not supported for this scenario, as this is a specific Marshal function.

See: Routing Common .NET Types

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one of the possible scenarios

C ++ side

    struct ArrayStruct
    {
        int myarray[2048];
        int length;
    };

    extern "C" __declspec(dllexport) void GetArray(ArrayStruct* a)
    {
        a->length = 10;
        for(int i=0; i<a->length; i++)
            a->myarray[i] = i;
    }

C # side

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    public struct ArrayStruct
    {
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2048)]
        public int[] myarray;
        public int length;
    }

    [DllImport("TaskLib.dll", CallingConvention = CallingConvention.Cdecl)]
    public static extern void GetArray(ref ArrayStruct a);

    public void foo()
    {
        ArrayStruct a = new ArrayStruct();
        GetArray(ref a);
    }
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