This routine links the total area to a FIELD or RTEXT so that if you stretch a polyline, the total updates automatically (requires advanced Visual LISP using reactors).

If you work in architecture, civil engineering, or interior design, you know the drill: you receive a complex floor plan, a site layout, or a zoning exhibit, and your client asks, "What is the total square footage?" Not the area of one room, not the zoning lot—the grand total. In native AutoCAD, calculating multiple areas and summing them manually is a tedious, error-prone process. You can use the AREA command with the "Add" option, but it is clunky. You can create hatches and check their properties, but that takes too long.

;; Step 2: Exit if nothing is selected (if (null ss) (princ "\nNo valid objects selected.") (progn (setq total 0.0) ; Initialize total to zero (setq i 0) ; Initialize counter