Help with newbie in loops

[Maradona_10]

HI all hope to not bother too much but i got a little problem...

 

What i want to do is to code something that calculates the area of a random close shape. I can ez use the area command BUT my problem that i have to use a loop so that i can keep cliking on points (the corners of the shape). so ill be someting like

 

(while

click on the first point

click on the next point etc....[end? Y/N?] ;;something that tell that this point is the last point

 

)

 

(print "the area is :" area )

[CAB]

Not sure where this code came from but it uses a selection set.

(DEFUN C:TOTAREA (/ tarea ss1 sn sn2 et) 
(setq cmdecho (getvar "cmdecho")) 
(setvar "cmdecho" 0) 
(setq tarea 0) 
(prompt "\nSelect only those entities you want for total area: ") 
(setq ss1 (ssget)) 
(while (> (sslength ss1) 0) 
 (setq sn (ssname ss1 0)) 
 (setq ent (entget sn)) 
 (setq et (cdr (assoc '0 ent))) 
 (command "area" "o" sn) 
 (setq tarea (+ tarea (getvar "area"))) 
 (ssdel sn ss1) 
) 
(setq tarea (/ tarea 144)) 
(alert (strcat "\nThe Total AREA of Selected Polylines is: " (rtos tarea 2 2))) 
(setvar "cmdecho" cmdecho) 
(princ) 
) 

[CAB]

Here is a loop example:

(defun c:test(/ ename pick)
 (setvar "errno" 0)               ; must pre set the errno to 0 
 (while (and (null (setq ename (entsel "\nSelect object.")))
              (= (getvar "errno") 7))
   (if (= (getvar "errno") 52) ; exit if user pressed ENTER
     (exit)
   )
   (prompt "\nMissed, Try again.")
 )
 (if ename  (setq pick  (cadr ename)
                   ename (car ename))
 )
)

[CAB]

A subroutine example:

(defun getEntity (msg enttype / picked ent return)
 ;;  enttype may be nil
 (setvar "ErrNo" 0) ; reset variable
 (while
   (not
     (cond
       ((and (null (setq picked (entsel msg)))
             (/= 52 (getvar "ErrNo")) ; <Enter> was not hit
        )
        (prompt "\nMissed, Try Again.")
       )
       ((null picked) t) ; [ENTER] pressed, exit loop, return nil
       ((progn
          (setq ent (car picked))
          (cond
            ((null enttype) (setq return ent))
            ((= (strcase enttype) (cdr (assoc 0 (entget ent))))
             (setq return ent)
            )
            (t (prompt "\nWrong entity type, Try Again."))
          )
        )
       )
     )
   )
 )
 return
)