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863 :: Testing a number for being prime (not totally serious)

• OderWat (orginal) [2015-02-13T04:47:23+01:00] view original

  I just read this (old) blog entry which was posted to hackernews and thought: Fair enough. Let's do it with Nim!

  It is 4:41 am and I have a serious flu. Don't ask! :)

  # regular expression to check a number for being prime
  
  import re, strutils
  
  let rprime = re r"^1?$|^(11+?)\1+$"
  
  proc testPrime(n: int): bool =
      not (repeatChar(n, '1') =~ rprime)
  
  for n in 1..10_000:
      echo n, " is", if not testPrime n: " not" else: "", " prime"
  Run

  Source / Gist

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• def (orginal) [2015-02-13T10:39:51+01:00] view original

  A bit easier:

  let rprime = re"^1?$|^(11+?)\1+$"
  Run

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• OderWat (orginal) [2015-02-13T14:48:52+01:00] view original

  @def .. that should be "\\1" normally. But right: "Constructor of regular expressions. Note that Nim's extended raw string literals support this syntax re"[abc]" as a short form for re(r"[abc]")."

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