Re: separating words

Edward Fagan wrote:

         Something like this function will tell you the position of
the last comma in a string.
 
(defun find-last-comma (s)
  (loop for n from 0 below (length s)
      if (char= (aref s n) #\,)
      do
        (if (and (loop for n downfrom (1- (length s)) to 0
                     if (char= (aref n s) #\,)
                     return n
                     finally (return nil))
                 (= n (loop for n downfrom (1- (length s)) to 0
                          if (char= (aref s n) #\,)
                          return n
                          finally (return nil))))
            (return-from find-last-coma n))
      finally (return nil)))

Testing in SBCL:

* (FIND-LAST-COMMA "hi, hi, ho")

debugger invoked on a SIMPLE-TYPE-ERROR in thread
#<THREAD "main thread" RUNNING {23EAC201}>:
  Value of N in (AREF N S) is 9, not a ARRAY.


Gauche Scheme

(string-scan-right "hi, hi, ho" #\,)
  ===>
6

(string-scan-right "hi, hi, ho" #\,  'before)
  ===>
"hi, hi"

(string-scan-right "hi, hi, ho" #\,  'after)
  ===>
" ho"