string-index

Description

Returns the position of the first occurance of target in source, or -1 if it does not occur.

Author

Norman Walsh, <ndw@nwalsh.com>

Source Code

(define (string-index source target)
  ;; Finds first occurance of 'target' in 'source'
  (let loop ((str source) (pos 0))
    (if (< (string-length str) (string-length target))
	-1
	(if (string=? (substring str 0 (string-length target)) target)
	    pos
	    (loop (substring str 1 (string-length str))
		  (+ pos 1))))))