HOWTO: Implement Array Arguments in Visual Basic COM Objects for Active Server Pages

• Active Server Pages
• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0

SUMMARY

This article describes, by example, how to implement arrays to be passed as parameters from Active Server Pages (ASP) to a Visual Basic 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 as any other type may generate one of the following errors:

error 'ASP 0115' - A trappable error occured in an external object

-or-

Invalid procedure call or argument

-or-

Type Mismatch

-or-

Object Does not Support This property or method

MORE INFORMATION

Use the following steps to implement arrays to be passed as parameters from (ASP) to a Visual Basic COM Object:

1. Create a Visual Basic ActiveX Dll project called ASPArray.



2. Change the name of the class module to clsArray.



3. Implement the following function:
   

   
   Public Function TestArray( ByRef vArray as Variant ) as String
     Dim nCnt as integer
   
     'Check that the argument passed is an array
     If Not IsArray( vArray ) Then
       TestArray = "Parameter is not an Array"
       Exit Function
     End If
   
     For nCnt = LBound(vArray) to UBound(vArray)
         'Traverse Array Element        
     Next nCnt
       
     TestArray = "Parameter is an Array"
   End Function 




4. 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.clsArray")
     vRtnValue = oTestObj.TestArray( vMyArray )
     Response.Write( "Return Value = " & vRtnValue )
   %>   

Additional query words:

Keywords          : kbASP kbCOMt kbVBp600 kbGrpASP 
Version           : WINDOWS:5.0,6.0; winnt:
Platform          : WINDOWS winnt 
Issue type        : kbhowto 

Last Reviewed: May 25, 1999