MFC ColeSafeArray Usage

From:
"Eric Hill" <eric@ijack.net>
Newsgroups:
microsoft.public.vc.mfc
Date:
Wed, 21 Feb 2007 08:59:56 -0600
Message-ID:
<op.tn3s960msqk0wa@wcerich-6223.pioneer.world>
My apologies if this isn't the best place to ask.

I'm writing some VC++ code to control Microsoft MapPoint and =

programmatically import some data. The main "magic function" that makes=
  =

the MapPoint world go around is DisplayDataMap, conveniently documented =
at =

the following URL.

http://msdn2.microsoft.com/en-us/aa562363.aspx

I'm trying to call this function with the geoDataMapTypeMultipleSymbol m=
ap =

type, and that involves passing some additional arrays in the =

"ArrayOfCustomValues" and "ArrayOfPushpinSymbols" values. I have tried =
 =

dozens of variations on the call, but it keeps throwing an OLE error "Th=
e =

parameter is incorrect."

I googled for several hours and came across an article talking about how=
  =

to call the code with C#. The examples given show the parameters being =
 =

passed as "object[]" arrays, not "string[]" arrays. After some testing =
in =

C#, I found that the parameters do indeed need to be passed as "object[]=
" =

arrays, or the C# code will throw the same incorrect parameter error.

My code that converts the vector<wstring> arrays to variant arrays is as=
  =

follows:

VARIANT wsvec_to_varray(std::vector<std::wstring> vec) {
    COleSafeArray varArray;
    DWORD elements[] = { vec.size() };
    varArray.Create(VT_BSTR, 1, elements);
    for (long i = 0; i < vec.size(); i++) {
        CString cs(vec[i].c_str());
        VARIANT v;
        VariantInit(&v);
        V_VT(&v) = VT_BSTR;
        v.bstrVal = cs.AllocSysString();
        varArray.PutElement(&i, v.bstrVal);
        SysFreeString(v.bstrVal);
        VariantClear(&v);
    }
    return varArray.Detach();
}

This code does indeed produce a variant array that the code inspector is=
  =

perfectly happy with, but I believe the VT_BSTR array item type means th=
is =

array is like a "string[]" array, not an "object[]" array. Does anyone =
 =

know the right way to create an "object[]" compatible variant array =

containing a list of strings?

Eric

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