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4078 :: String bound check allow to access last null char?

• Ward (orginal) [2018-07-25T06:51:24+02:00] view original

  Consider this code:

  var a = @[1, 2, 3]
  echo a[a.len]
  Run

  Of course we will get an IndexError: "index out of bounds". However, this code will pass.

  var s = "123"
  echo s[s.len]
  Run

  We even can modify the last null char. Is this a bug or a default behavior? Anyway, I think it's not safe.

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• timothee (orginal) [2018-07-25T06:56:50+02:00] view original

  this has been fixed in devel some time ago

  nim --version Nim Compiler Version 0.18.1 [MacOSX: amd64] Compiled at 2018-07-24 Copyright (c) 2006-2018 by Andreas Rumpf

  git hash: d5c9255cab9c111f8fa930e4cd42d6671877bd9d active boot switches: -d:release

  inim INim 0.3.0 Nim Compiler Version 0.18.1 [MacOSX: amd64] at /Users/timothee/.nimble/bin/nim >>> var s = "123" >>> echo s[s.len] inim_1532494547

  /Users/timothee/git_clone/nim/Nim/lib/system.nim(2807) sysFatal

  Error: unhandled exception: index out of bounds [IndexError] Error: execution of an external program failed: '/private/tmp/inim_1532494547 ' >>> echo s[s.len-1] 3

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