[编程交流] 检查是否存在对象或形状

(defun c:tinklolinija (/ test pradzios_taskas)
 (vl-load-com)
(while
(if (tblsearch "block" "Piketas")
(princ "\nBlock Piketas not found.")
)
)
 (princ)
)

(setq ss (ssget "X" (list (cons 0 "Insert")(cons 2 "Picket"))))

(defun c:bcount ( / p1 b a n obj name)
(setq p1 (getstring "\Name of Block : "))
;get the name of the block
(setq b (cons 2 p1))
;construct a dotted pair - code 2 is for blocks
(setq a (ssget "x" (list b)))
;filter for the block name
     (progn
    )
(if (/= a nil)
;check if there are any blocks of that name
   (progn
   ;if there is…
        (setq n (sslength a))
    (setq ent (entlast a))
        ;count the number of blocks
        (alert (strcat "\nThere are " (itoa n)  " in the DataBase. Enity: " (itoa ent) ))
    
        ;display the result
   );progn
   ;if there are no blocks
        (alert "\nThere are none in the DataBase")
        ;inform the user
);if
  (princ)
)

(vl-load-com)
(setq entity
      (car
    (entsel "\nSelect Item: ")    ; select item
      )
)
(if entity                ; check if something selected
 (progn                ; if so, do some stuff
   (princ (strcat "\nEntity is a: "    ; combine some strings
          (vl-princ-to-string (type entity))
                   ; convert type-output to string
      )
   )
   (princ (strcat "\nThe entity name is: "
          (vl-princ-to-string entity)
      )
   )
 )
)
(princ "\nAnd now VLA-data:")
(setq a-vla-object
      (vlax-ename->vla-object entity)    ; convert a ename to a vla-object
)
(princ
 (strcat "\nVLA-Entity: " (vl-princ-to-string a-vla-object))
)