Cant cast from object to acadarc

[mpropst]

I get the following error

<Unable to cast object of type 'System.Object[]' to type 'Autodesk.AutoCAD.Interop.Common.AcadArc'.>

on these lines

 Dim oArc3 As AcadArc
 Dim oArc4 As AcadArc
        If oArc1.Radius > oArc2.Radius Then
            oArc3 = DirectCast(oArc1.Offset(BASE_SHELL_OFFSET), AcadArc)
            oArc4 = DirectCast(oArc2.Offset(-BASE_SHELL_OFFSET), AcadArc)

        Else
            oArc3 = DirectCast(oArc1.Offset(-BASE_SHELL_OFFSET), AcadArc)
            oArc4 = DirectCast(oArc2.Offset(BASE_SHELL_OFFSET), AcadArc)
        End If

oArc1 and oArc2 are acad arcs(obviously) - but the .Offset method sig returns an object not an arc (how weird is that?)

what's the solution with option strict on?

[mpropst]

ps without trying to cast to arc i get the following error

oArc3 = oArc1.Offset(BASE_SHELL_OFFSET)
oArc4 = oArc2.Offset(-BASE_SHELL_OFFSET)

produces the compile error

option strict on disallows implicit conversion from object to acad arc (or something close to that wording)

[mpropst]

duh! i see it now.

Offset returns array of object, not object

[norman.yuan]

Well, it only goes as weird as your code goes

The Offset() method returns a variant (in VBA)/object (in .NET), which is and ARRAY of entity generated by the method. You cannot cast an array to an AcadArc/AcadEntity, of course. Depending on the original entity type, the generated entity may not be the same type. Here is the quote from VBA document:

<quote>

For many curves, the result of this operation will be a single new curve (which may not be of the same type as the original curve). For example, offsetting an ellipse will result in a spline because the result does not fit the equation of an ellipse. In some cases it may be necessary for the offset result to be several curves.

</quote>

In your case, it is lucky enough, you get a single AcadArc back (i.e. one AcadArc element in the returned array). So, your code should look like this:

oArc3 = DirectCast(oArc1.Offset(BASE_SHELL_OFFSET)(0), AcadArc)

[mpropst]

yes, thanks

I did finally see that array business.

thanks for your response

mark