C# 将对象传递给COM方法

我有一个api用于我正在使用的第三方应用程序。在api中，他们说需要传入“VARIANTARG”类型的输入参数

所以我在网上找到了这个，在C#中使用VARIANTARG：

这是我的问题。此VARIANTARG对象中有两个属性，我不确定如何设置：

public unsafe ushort* bstrVal;
public unsafe ushort** pbstrVal; // Note the double pointer on this one

以下是我尝试过的：

VARIANTARG v = new VARIANTARG();

//---------------------------------
//??? What goes here??? ???
string myString = "aaa";
v.bstrVal = &myString;
//  public unsafe ushort* bstrVal;
//??? and here:
v.pbstrVal = "???";
//  public unsafe ushort** pbstrVal;
//---------------------------------

MyCOMObj_App.SendTag(v);

您能告诉我如何将这两个属性设置为某个字符串值，以及如何将其传递给COM方法吗

仅供参考…以下是VARIANTARG结构定义：

StructLayout(LayoutKind.Explicit, Size=16)]
struct VARIANTARG {
    [FieldOffset(0)]
    public ushort vt;

    [FieldOffset(2)]
    public ushort wReserved1;

    [FieldOffset(4)]
    public ushort wReserved2;

    [FieldOffset(6)]
    public ushort wReserved3;

    [FieldOffset(8)]
    public long llVal;

    [FieldOffset(8)]
    public int lVal;

    [FieldOffset(8)]
    public byte bVal;

    [FieldOffset(8)]
    public short iVal;

    [FieldOffset(8)]
    public float fltVal;

    [FieldOffset(8)]
    public double dblVal;

    [FieldOffset(8)]
    public short boolVal;

    [FieldOffset(8)]
    public int scode;

    //[FieldOffset(8)]
    //public CY cyVal;

    [FieldOffset(8)]
    public double date;

    [FieldOffset(8)]
    public unsafe ushort* bstrVal;

    //[FieldOffset(8)]
    //public unsafe IUnknown* punkVal;

    //[FieldOffset(8)]
    //public unsafe IDispatch* pdispVal;

    //[FieldOffset(8)]
    //public unsafe SAFEARRAY* parray;

    [FieldOffset(8)]
    public unsafe byte* pbVal;

    [FieldOffset(8)]
    public unsafe short* piVal;

    [FieldOffset(8)]
    public unsafe int* plVal;

    [FieldOffset(8)]
    public unsafe long* pllVal;

    [FieldOffset(8)]
    public unsafe float* pfltVal;

    [FieldOffset(8)]
    public unsafe double* pdblVal;

    [FieldOffset(8)]
    public unsafe short* pboolVal;

    [FieldOffset(8)]
    public unsafe int* pscode;

    //[FieldOffset(8)]
    //public unsafe CY* pcyVal;

    [FieldOffset(8)]
    public unsafe double* pdate;

    [FieldOffset(8)]
    public unsafe ushort** pbstrVal;

    //[FieldOffset(8)]
    //public unsafe IUnknown** ppunkVal;

    //[FieldOffset(8)]
    //public unsafe IDispatch** ppdispVal;

    //[FieldOffset(8)]
    //public unsafe SAFEARRAY** pparray;

    [FieldOffset(8)]
    public unsafe VARIANTARG* pvarVal;

    [FieldOffset(8)]
    public unsafe void* byref;

    [FieldOffset(8)]
    public sbyte cVal;

    [FieldOffset(8)]
    public ushort uiVal;

    [FieldOffset(8)]
    public uint ulVal;

    [FieldOffset(8)]
    public ulong ullVal;

    [FieldOffset(8)]
    public int intVal;

    [FieldOffset(8)]
    public uint uintVal;

    //[FieldOffset(8)]
    //public unsafe DECIMAL* pdecVal;

    [FieldOffset(8)]
    public unsafe sbyte* pcVal;

    [FieldOffset(8)]
    public unsafe ushort* puiVal;

    [FieldOffset(8)]
    public unsafe uint* pulVal;

    [FieldOffset(8)]
    public unsafe ulong* pullVal;

    [FieldOffset(8)]
    public unsafe int* pintVal;

    [FieldOffset(8)]
    public unsafe uint* puintVal;

    [FieldOffset(8)]
    public unsafe void* pvRecord;

    //[FieldOffset(12)]
    //public unsafe IRecordInfo* pRecInfo;

    //[FieldOffset(0)]
    //public DECIMAL decVal;
}

---

结构表示一个变体，这里作为C++联盟实现。有许多字段重叠，例如bool、float、long等。您不需要设置所有字段，只需要设置一个字段和类型。 例如，见： 哪一个取决于调用哪个函数；它应该告诉您它需要什么类型的输入