Lee McDonnell is back again, this time with a routine that labels AutoCAD entities with their length. This routine works for circles, lines, arcs, and polylines. Start by loading the LISP file and run the command PLL. After you select the objects, an mtext label will be created at the midpoint of each entity, containing a field with the entity length. Circles are labeled at the 180° (or left quadrant) point. Because a field is created, the label will update if the entity's length is changed. Labels are created using the current Units settings for type and precision.
I found this to be a handy tool for visually inspecting the length of several lines at once. I can label them, inspect as needed, then remove the labels using Undo. This is faster and easier than using the List command.