length-string-number-part

Description

Given a length as a string, return the numeric part.

Example

"100pt" returns "100". "30" returns "30". "in" returns "".

Author

Norman Walsh, <ndw@nwalsh.com>

Source Code

(define (length-string-number-part lenstr)
  ;; Returns the numeric part of a length string
  (let ((digits '(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9 #\.)))
    (let loop ((chars (string->list lenstr))
	       (number-part ""))
      (if (or (null? chars) (not (member (car chars) digits)))
	  number-part
	  (loop (cdr chars) (string-append number-part 
					   (string (car chars))))))))