一个用于图块置换的程序，但不知为什么有缺陷？

weixin7944

下面是一个由我自己编的图块置换的程序，但是每次运行程序时，所要置换的图块总是没有完全置换完，要分好几次置换！请指教，谢谢！ (defun c:th (/ database a c d e f g n da)
(setq database (entget (car(entsel "请选择要修改的图块!"))))
(PRINT (STRCAT "当前的图块是:" (cdr (assoc '2 database))))
(setq g (cdr (assoc '2 database))) (setq a (getstring (strcat "\n请输入修改后的图块名：<"(getvar "INSNAME") "> ")))
(COND
((/= A "") (setvar "INSNAME" a))
((= A "") (setq a (getvar "INSNAME")))
)
(setq c (getpoint "the first point:"))
(setq d (getcorner c "the second point:"))
(setq e (ssget "w" c d))
(setq n (sslength e))
(PRINT N) (setq f 0)
(repeat n
(setq da (entget (ssname e f))) (if
(= (cdr (assoc '2 da)) g)
(progn
(setq da (subst (cons 2 a) (assoc '2 da) da))
(entmod da))
(setq f (1+ f))
)
))

meflying

(= (cdr (assoc '2 da)) g)这句不论是真还是假，都必须执行(setq f (1+ f))，所以(setq f (1+ f))必须放到if的外面