Click Editor on the Editor toolbar and click Start Editing.
You can make calculations without being in an editing session; however, in that case, there is no way to undo the results.
Right-click the shapefile layer you want to edit and click Open Attribute Table.
Right-click the field heading for length and click Calculate Values.
If there is no field for length values, you can add a new field for length by clicking the Options button and selecting Add Field. However, to add a new field, you need to exit the editing session.
Click Calculate Values.
Check Advanced.
Type the following VBA statement in the first text box:
Dim dblLength as double
Dim pCurve as ICurve
Set pCurve = [shape]
dblLength = pCurve.Length
Type the variable dblLength in the text box directly under the length field name.
Click OK.
Tip
The property length returns a field type of double. For best results, your length field should also be a double field type.
