Iterating Backwards in C

4 comments

• kenferry 32 minutes ago
  I know it's "too clever", but if I'm writing code no one else will ever see,

    while (i --> 0) {
        // use array[i]
    }
  

  easy to read (if not understand), and correct!
  [-]
  • viega 17 minutes ago
    I always use unsigned values and do:

      while (i-- != 0) { ... }
    

    It's more clear than the most idiomatic way, which is to drop the explicit comparison:

      while (i--) { ... }
     

    All of it is better than the clunky old for-loop syntax.
  • krackers 25 minutes ago
    Oh I remember this from the classic SO post, but it was just presented as a funny trick. I never realized that it solves the issue mentioned in the article and there is a legitimate use-case for post-decrement in the comparison itself.

    https://stackoverflow.com/questions/1642028/what-is-the-oper...
  • stephencanon 30 minutes ago
    Always.

    (Hi Ken!)
• MaulingMonkey 49 minutes ago
  I prefer:

      const size_t n = 10;
      for (size_t i = n; i --> 0;) {
          std::cout << i << "\n";
      }

  [-]
  • hedgehog 40 minutes ago
    That's a certain kind of taste... I checked out your home page, game dev, check, and this work of art is worth linking (no irony, I love it):

    http://maulingmonkey.com/brainfuck/
  • ranger_danger 40 minutes ago
    Cute but wouldn't work with ssize_t :)

    VHDL's array/vector syntax actually works a similar way:

    -- gives 0, 1, 2, 3:

    for i in 0 to 3 loop

    -- gives 3, 2, 1, 0:

    for i in 3 downto 0 loop

    -- Source - https://stackoverflow.com/a/7642026 -- Posted by Kerrek SB -- Retrieved 2026-10-29, License - CC BY-SA 3.0

    [-]
    • fourthark 13 minutes ago
      Does work with ssize_t, just not necessary.
• abstractspoon 2 days ago
  I've been using this method for more than 30 years!
• rpsworld 53 minutes ago
  [flagged]