How to insert a character into a string a specific location?

[mid-awe]

Hi all,

I am sure this is an easy task but I am having some trouble remembering how to insert a Letter into a string at a specific location. 

I'm trying to get the (VL-FILENAME-BASE (GETVAR 'DWGNAME)) and insert a (chr 86) after the 8th character, so that the inserted letter becomes the 9th letter/number only if it is not already present.

example:

23-01472r7

becomes:

23-01472Vr7

I hope that this makes sense. Any help is greatly appreciated.

Thank you in advance.

[Kent1Cooper · Accepted solution]

---

@mid-awe wrote:

.... 

I'm trying to .... insert a (chr 86) after the 8th character, so that the inserted letter becomes the 9th letter/number only if it is not already present.

....

---

How about something like:

(if (/= (substr YourString 9 1) "V"); not already present

  (setq YourString (strcat (substr YourString 1 8) "V" (substr YourString 9)))

)

If the original is not at least 9 characters long, it will simply add "V" to the end.

[mid-awe]

Thank you Kent, that did it perfectly.

[Moshe-A · Accepted solution]

hi,

check this:

(defun insert_string (string str p)
 (if (not (vl-string-search string str))
  (if (and (not (minusp p)) (<= p (strlen string)))
   (if (= p 0)
    (strcat str string)
    (strcat (substr string 1 p) str (substr string (1+ p)))
   )
  )
 ) 
)

(insert_string "23-01472r7" "V" 8)
"23-01472Vr7"

Moshe

[mid-awe]

Thank you Mosh for this reusable solution.

[Moshe-A]

thank you very much mid-awe

i forgot to insert p argument in (vl-string-search) this ensures that only if str

does not exist in the position in question the new add string is inserted.

(defun insert_string (string str p)
  (if (not (vl-string-search string str p))
   (if (and (not (minusp p)) (<= p (strlen string)))
    (if (= p 0)
     (strcat str string)
     (strcat (substr string 1 p) str (substr string (1+ p)))
    )
   )
  )  
)

notice that the (insert_string) function let you insert a str in front of string (p=0)

and at the end but it won't let you insert a string if the index p is out of range

moshe

[mid-awe]

Thanks again 🙂