[racket] string-trim : an implementation & a question

You can use an index to the string to find the location of your goal, then return the substring when you are done.

rac

On Apr 2, 2011, at 3:08 PM, Charles Hixson wrote:

> This seems to be what I want the string-trim to do, but it seems that all the string copying would be expensive.  Is there a way to improve it by avoiding the string copying?
> 
> My original inclination was to use a while loop with a test for non-whitespace, but that appears to not be something scheme supports.
> 
> (define (string-trim s)
>    (let ( (l (string-length s) ) )
>      (cond
>        [ (= l 0) #f]
>        [ (char-whitespace? (string-ref s (- l 1) ) )    (string-trim (substring s 0 (- l 1) ) ) ]
>        [else s]) ) )
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