String split function

Question

I am just wondering if there is the string split function? Something like:

> (string-split "19 2.14 + 4.5 2 4.3 / - *")
'("19" "2.14" "+" "4.5" "2" "4.3" "/" "-" "*")

I haven't found it and created my own. I use Scheme from time to time so I'll be thankful if you fix it and suggest the better solution:

#lang racket

(define expression "19 2.14 + 4.5 2 4.3 / - *")

(define (string-split str)

  (define (char->string c)
    (make-string 1 c))

  (define (string-first-char str)
    (string-ref str 0))

  (define (string-first str)
    (char->string (string-ref str 0)))

  (define (string-rest str)
    (substring str 1 (string-length str)))

  (define (string-split-helper str chunk lst)
  (cond 
    [(string=? str "") (reverse (cons chunk lst))]
    [else
     (cond
       [(char=? (string-first-char str) #\space) (string-split-helper (string-rest str) "" (cons chunk lst))]
       [else
        (string-split-helper (string-rest str) (string-append chunk (string-first str)) lst)]
       )
     ]
    )
  )

  (string-split-helper str "" empty)
  )

(string-split expression)

You should put your closing parens on the same line as the last expression. This isn't C :) — erjiang, Oct 10 '11 at 02:28

score 13 · Accepted Answer · answered Oct 07 '11 at 19:26

13

Oh my! That's a lot of work. If I understand your problem correctly, I would use regexp-split for this:

#lang racket
(regexp-split #px" " "bc thtn odnth")

=>

Language: racket; memory limit: 256 MB.
'("bc" "thtn" "odnth")

answered Oct 07 '11 at 19:26

John Clements

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Usually something like `#px" +"` or `#px"[[:space:]]"` is more appropriate. (In case that was the intention.) – Eli Barzilay Oct 08 '11 at 01:37

score 9 · Answer 2 · answered May 17 '15 at 07:32

Well, you can use plain old string-split

> (string-split "19 2.14 + 4.5 2 4.3 / - *")
'("19" "2.14" "+" "4.5" "2" "4.3" "/" "-" "*")

It is part of racket http://docs.racket-lang.org/reference/strings.html#%28def._%28%28lib._racket%2Fstring..rkt%29._string-split%29%29

erjiang · Answer 3 · 2011-10-10T23:19:34.197

7

Just as a reference for other Schemers, I did this in Chicken Scheme using the irregex egg:

(use irregex)

(define split-regex
  (irregex '(+ whitespace)))

(define (split-line line)
  (irregex-split split-regex line))

(split-line "19 2.14 + 4.5 2 4.3 / - *") =>
("19" "2.14" "+" "4.5" "2" "4.3" "/" "-" "*")

edited Oct 10 '11 at 23:19

answered Oct 10 '11 at 02:32

erjiang

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If you don't want to copy that definition every time, `(string-split)` is also a part of the `coops` egg, which has some other nice string stuff. Unfortunately it's not documented on its doc page. – user1610406 May 15 '16 at 21:19

String split function

3 Answers3