如何用vb取得autoCAD图中的Polyline的周长?

使用length属性取得autoCAD图中的单根Polyline的周长。
Sub GetLengthOfPolyline()
On Error Resume Next

Dim Ent As AcadEntity
Dim Pnt As Variant

Do
ThisDrawing.Utility.GetEntity Ent, Pnt, "选择多段线："
If Err Then Exit Do
If TypeName(Ent) Like "IAcad*Polyline" Then
ThisDrawing.Utility.Prompt vbLf & "多段线长度为："
ThisDrawing.Utility.Prompt vbLf & Ent.Length & vbLf
Exit Do
End If
Loop
End Sub