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605 :: Assign to sequence inside a proc

• jarod (orginal) [2014-10-28T03:52:12+01:00] view original

  I've got a procedure that I want to make assign to a sequence based off of the contents inside a text file:

  proc assign_seq(sequence: seq[string], filename: string) =

  var

  file = readFile(filename)

  i : int = 0

  for word in split(file, {'/'}):

  sequence[i] = word

  i += 1

  However when I call this function inside another e.g.

  assign_seq(names, "names.txt")

  It says not able to assign to sequence[i].

  I checked the documentation and it said to use var in the procedures parameters, however I get an illegal access error whenever I try this. How would I go about making the sequence get assigned in the way I want it to (storing the list of names separated by a '/' inside the sequence?)

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• gradha (orginal) [2014-10-28T10:16:36+01:00] view original

  The illegal access error is because you are likely not reserving memory for your sequence before calling assign_seq(). Example:

  
  names = @[]
  assign_seq(names, filename)
  Run

  But then the code you show will fail with an index out of bounds error…

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• jarod (orginal) [2014-10-28T11:01:12+01:00] view original

  Ah thanks that was a bit obvious, I imagine I could just fix that out of bounds error by using newSeq with the length of the file or something similar. I'll test it out and edit this post if it does work. Thanks for the help.

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• gradha (orginal) [2014-10-28T11:20:05+01:00] view original

  Arrays don't grow, but sequences can change size at runtime. You can preallocate one and add stuff to it later without having to keep track of indices or expected sizes:

  
  
  var a: seq[string] = @[]
  a.add("a")
  a.add("b")
  a.add("c")
  Run

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• jarod (orginal) [2014-10-28T11:25:48+01:00] view original

  Bingo that fixed it! I changed it from sequence[i] = word to sequence.add(word). Thanks gradha.

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