please notify me which part is wrong

[sm022453760286]

I want to draw a simple bolt using AutoLISP
I wanted to input the diameter of bolt using getreal and to load the data related to the diameter what I input already.
But Error message occured "stringp nil".
please notify me which part is wrong

(defun bolt()
  (setq fo (open "C:/Bolt.txt" "r"))
  (while (/= bolt_d data_bolt_1)
    (setq bolt_d (getreal "Enter the diameter of bolt"))
    (setq data_bolt (read-line fo))
    (setq data_bolt_1 (atof (substr data_bolt 2 4)))
    )
  
  (setq bolt_l (getreal (princ (substr data_bolt 76 6))))
  (setq bolt_m (atof (substr data_bolt 6 5)))
  (setq bolt_b (atof (substr data_bolt 11 5)))
  (setq bolt_dkmx (atof (substr data_bolt 16 5)))
  (setq bolt_da (atof (substr data_bolt 21 5)))
  (setq bolt_ds (atof (substr data_bolt 26 5)))
  (setq bolt_e (atof (substr data_bolt 31 5)))
  (setq bolt_lf (atof (substr data_bolt 36 5)))
  (setq bolt_k (atof (substr data_bolt 41 5)))
  (setq bolt_r (atof (substr data_bolt 46 5)))
  (setq bolt_s (atof (substr data_bolt 51 5)))
  (setq bolt_t (atof (substr data_bolt 56 5)))
  (setq bolt_v (atof (substr data_bolt 61 5)))
  (setq bolt_dw (atof (substr data_bolt 66 5)))
  (setq bolt_w (atof (substr data_bolt 71 5)))

  (setq pt0 '(0 0))
  (setq pt1 (polar pt0 (/ pi 2) (- (/ bolt_dk 2) (bolt_v))))
  (setq pt2 (polar pt1 (/ pi 4) (/ bolt_v (cos(/ pi 4)))))
  (setq pt3 (polar pt2 0 (- bolt_k bolt_v)))
  (setq pt4 (polar pt3 (/ pi -2) (- (/ bolt_dk 2) (/ bolt_da 2))))
  (setq pt5 (list (+ bolt_lf) (- (- (/ bolt_da 2) (/ bolt_ds 2)))))
  (setq pt6 (polar pt5 0 (- bolt_l (* bolt_P 2))))
  (setq pt7 (polar pt6 (/ pi -4) (/ bolt_v (cos (/ pi 4)))))
  (setq pt8 (polar pt7 (/ pi -2) (- (/ bolt_d 2) (* bolt_P 2))))
  (setq pt9 (polar pt8 (/ pi 2) (/ bolt_dk 2)))

  (command "pline" pt0 pt1 pt2 pt3 pt4 pt5 pt6 pt7 pt8 "C")

  (setq ss1 (ssget "C" pt7 pt8))
  (command "mirror" ss1 "" pt0 pt8 "N")
  )

[rkmcswain]

Did you try editing this in the VLIDE? It will tell you where the error occurs.

I'll look in just a bit. (Oops, can you post the bolt.txt file?)

[sm022453760286]

Okay. I will attach "bolt.txt" thanks

[rkmcswain]

You're never closing the open file.

I would suggest doing this:

1. Open the file
2. Read the entire contents into a list
3. Close the file

This way you don't have the file open any longer than needed, reducing the chance of error.

Now you have the contents of the file in a list, you can iterate this list looking for the match.

(setq fo (open "Bolt.txt" "r"))
  (while (setq a (read-line fo))
    (setq lst (cons a lst))
  )
(close fo)
(reverse lst)

[BIG-AL]

I am going to suggest something bold stop what your doing get a dynamic bolt block, just place click set size and length all done.