Topic: Determine if string1 is a rotation of string2

[pkohut]

Saw this question in StackOverflow and thought it interesting. How about some Autolisp solutions to the problem.

Given 2 strings s1 and s2 how will you check if s1 is a rotated version of s2?

Example:
if s1 = "stackoverlow" then the following are some of its rotated versions:
"tackoverflows"
"ackoverflowst"
"overflowstack"

where as "stackoverflwo" is not a rotated version.

The solution is at SO also, so don't look just yet 

[VovKa]

Code: [Select]

(defun test (s1 s2) (or (vl-string-search s1 (strcat s2 s2))))


[Kerry]

 

[Kerry]

except for

(test "TIT "TI")

[pkohut]

Code: [Select]

(defun test (s1 s2) (or (vl-string-search s1 (strcat s2 s2))))


Nice. Need to check that length of s1 and s2 are the same, but still nice and compact.

[pkohut]

except for

(test "TIT "TI")

What a boob 

[Lee Mac]

Another two 

Code: [Select]

(defun LM:isStringRotation ( s1 s2 )
  (vl-some
    (function
      (lambda ( s )
        (and (vl-string-search s1 s))
      )
    )
    (
      (lambda ( i )
        (mapcar
          (function
            (lambda ( x )
              (strcat (substr s2 (setq i (1+ i)))
                (substr s2 1 (1- i))
              )
            )
          )
          (vl-string->list s2)
        )
      )
      0
    )
  )
)


Code: [Select]

(defun LM:isStringRotation2 ( s1 s2 / foo )

  (defun foo ( s i )
    (if (< 0 i)
      (if (vl-string-search s1
            (strcat (substr s i) (substr s 1 (1- i)))) t
        (foo s (1- i))
      )
    )
  )

  (foo s2 (strlen s2))
)


[VovKa]

except for

(test "TIT "TI")

yep, my fault
i just can't program and think about tits at the same time

[JohnK]

Okay, just for kicks (I had to chew up the rest of my lunch break some how).

No one suggested this method yet so...

Code: [Select]

(setq s1 "stackoverflow"
      s2 "tackoverflows"
      s3 "ackoverflowst"
      s4 "overflowstack"
      is1 (vl-string->list s1)
      is2 (vl-string->list s2)
      is3 (vl-string->list s3)
      is4 (vl-string->list s4))
(mapcar '(lambda ( x )
   (equal
     (vl-sort is1 '<) (vl-sort (eval x) '<)))
'(is2 is3 is4))

[VovKa]

what about these?

Code: [Select]

(setq s1 "stackoverfloww"
      s2 "ttackoverflows"
      s3 "aackoverflowst"
      s4 "overflowstackk"
)


[JohnK]

hey, thats what you get for 10 minutes worth of programing.