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Article ID: 218454 - Last Review: July 1, 2004 - Revision: 4.2
How To Implement Array Arguments in Visual C++ COM Objects for Active Server Pages
This article was previously published under Q218454
This article describes, by example, how to implement arrays to be passed as
parameters from Active Server Pages (ASP) to a Visual C++ COM Object.
It is important to keep in mind that array arguments for methods must be declared as variant data type and must the passed by reference. Declaring an array argument any other way may cause an error, such as the following:
error 'ASP 0115' - A trappable error occured in an external object
-or-
Invalid procedure call or argument
-or-
-or-
Object Does not Support This property or method
Use the following steps to implement arrays to be passed as
parameters from ASP to a Visual C++ COM Object:
- Create an ATL DLL Project called ASPArray."
- Insert an ATL Object named VCArrayObj.
Add a Method with the following information:
Method Name: TestArray<BR/>
Parameters : [in, out] VARIANT* pArray, [out, retval] long* pVal<BR/>
- Implement the Method as follows:
STDMETHODIMP CVCArrayObj::TestArray(VARIANT *pArray, long *pVal)
{
SAFEARRAY *psa;
long lLBound, lUBound, cElements;
if( pArray->vt & VT_BYREF )
psa = *(pArray->pparray);
else
psa = pArray->parray;
//Check the Dimension of the Array
if ( SafeArrayGetDim( psa ) != 1 )
return E_INVALIDARG;
//Get the lower and upper bounds of the array
SafeArrayGetLBound( psa, 1, &lLBound );
SafeArrayGetUBound( psa, 1, &lUBound );
//Compute the Number of Elements
cElements = lUBound - lLBound + 1;
//Access the elements of the array
for ( long cCnt = lLBound; cCnt <= lUBound; cCnt++ )
{
VARIANT vVal;
SafeArrayGetElement( psa, &cCnt, &vVal );
}
*pVal = cElements;
return S_OK;
}
- Create an ASP page with the following code:
<%
Dim oTestObj, vMyArray(2), vRtnValue
vMyArray(0) = "Element 1"
vMyArray(1) = "Element 2"
vMyArray(2) = "Element 3"
Set oTestObj = Server.CreateObject("ASPArray.VCArrayObj")
vRtnValue = oTestObj.TestArray( vMyArray )
Response.Write( "Return Value = " & vRtnValue )
%>
APPLIES TO
- Microsoft Active Server Pages 4.0
- Microsoft Visual C++ 6.0 Enterprise Edition
- Microsoft Visual C++ 6.0 Professional Edition
- Microsoft Visual C++, 32-bit Learning Edition 6.0
- Microsoft Internet Information Server 4.0
- Microsoft Internet Information Services 5.0
| kbaspobj kbcodesnippet kberrmsg kbhowto KB218454 |
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