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8239 :: reverse cipher

• deoxyt2 (orginal) [2021-07-17T20:08:48+02:00] view original

  I'm new to NIm and I'm doing my first program, but I have a syntax problem that I can't discover and tried several alternatives but they don't work for me What's the problem with line 11?

  #reverse cipher

  var message: string = "mensaje secreto"

  var translated: string = ""

  var i: int

  i = ((message.len) - 1)

  while i >= 0:

  translated = translated.add(message[i]) echo (message[i])

  i = i - 1

  echo (translated)

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• miran (orginal) [2021-07-18T08:33:41+02:00] view original

  > translated = translated.add(message[i]) echo (message[i])

  1. add doesn't return a new string
  2. no need for parentheses in echo

  translated.add(message[i])
  echo message[i]
  Run

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• Stefan_Salewski (orginal) [2021-07-18T09:10:38+02:00] view original

  And a modified faster variant:

  #reverse cipher
  var
    message = "mensaje secreto"
    i = message.high
    translated: string = newString(i + 1)
  
  for j, c in message:
    translated[i - j] = c
  
  echo translated
  Run

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• cblake (orginal) [2021-07-18T15:16:03+02:00] view original

  If you really are only reversing, that is an included battery:

  import algorithm
  var message = "mensaje secreto"
  message.reverse
  echo message
  # Another way...
  let translated = "mensaje secreto".reversed
  echo cast[string](translated)
  Run

  (The cast is only need to format like a string not a seq[char].)

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• ynfle (orginal) [2021-07-18T18:32:30+02:00] view original

  Why would you cast and not join()

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• cblake (orginal) [2021-07-18T19:29:12+02:00] view original

  No great reason. I was probably too suggestible Re performance concerns which likely don't matter (yet!). I almost said "there are several ways to do this". That'll teach me to be brief! Lol. So, here, @deoxyt2...

  import strutils; echo translated.join # A 3rd way
  Run

  It actually might be a 5th way if you count the @miran and @Stefan_Salewski answers. And, yes, there are probably also several more, just within the stdlib. Might help newcomers to see various approaches. (I've often thought that RosettaCode could benefit from more attempts at "several answers" for each problem.)

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• deoxyt2 (orginal) [2021-07-21T06:26:20+02:00] view original

  well, thank you all, for what I see and as always, the magic is in the libraries, I'll take a tour of that documentation, again, thank you very much.

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