• Buddahriffic@lemmy.world
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    5 months ago

    I have a better odd/even function:

    bool isEven( long long x ) {  
      if ( x < 0 ) x = -x;  
      if ( x == 1 )  
        return false;  
      if ( x == 2 )  
        return true;  
      return isEven( x - 2 );  
    }
    

    This will work for both negative numbers and arbitrarily large integers. I’ve tested it up to 26 but I’m pretty sure it will work up to infinity.

    Though serious question: Why are these forums coded in such a way that they ignore single newlines? How hard is it to replace a newline with a br tag?

    Edit: added two spaces, should look much better.

    Edit2: just looks a bit better lol

    Edit3: better now?

    • oktoberpaard@feddit.nl
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      5 months ago

      It’s Markdown syntax. You can actually format it nicely in a code block:

      bool isEven( long long x ) {
        if ( x < 0 ) x = -x;
        if ( x == 1 )
          return false;
        if ( x == 2 )
          return true;
        return isEven( x - 2 );
      }
      

      You do that by adding ``` above and below it. To force single line breaks, you can terminate your sentences with two spaces, or a backslash.

      • Buddahriffic@lemmy.world
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        5 months ago

        Ah thank you, the editor in connect isn’t great and doesn’t have the markdown guide or buttons for the preformatted block, so I couldn’t find the character combo to use it (and never would have guessed that lol). Also it keeps giving an error when I edit, though the edit is going through.

    • ApexHunter@lemmy.ml
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      5 months ago

      Is this meant to be a joke or is it intended to be a serious solution?

      Asking for someone who lacks a sense of humor.

      Ok, fine, I’m asking for me. That person is me.

      • Buddahriffic@lemmy.world
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        5 months ago

        I want to see how you’d reply if I said it was serious. So let’s go with that. This is the best way to determine if a number is even in c/c++.

        • ApexHunter@lemmy.ml
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          5 months ago

          The reply would have been return x % 2 == 0, or if you wanted it to be less readable return !(x&1).

          But if you were going for a way that is subtly awful or expensive, just do a regex match on “[02468]$”. You don’t get a stack overflow with larger numbers but I struggle to think of a plausible bit of code that consumes more unnnecessary cycles than that…

          • Buddahriffic@lemmy.world
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            5 months ago

            The less readable one is faster, though I’d be surprised if the compiler doesn’t generate the same code for both of those options with optimizations enabled.

            I like the regex one as another unnecessarily complicated way of doing it. It also involves a string conversion.

            The way that was being hinted at before my reply was a large series of if statements: is it 2? 4? 6? 8? And so on. It’s plausible in that I could see a beginner programmer using that method. And honestly, knowing how people can get pigeon holed into looking at a problem from some weird angle but still having the determination to figure it out, most solutions are plausible. Often when they get pointed in a better direction, it’s not so much a case of them learning something new as it is a facepalm kinda moment where they feel embarrassed at not seeing that. I’ve done it myself many times lol.

            It’s always funny seeing someone use the wrong tool for the job but still getting the job done, even when it’s me.

              • Buddahriffic@lemmy.world
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                5 months ago

                Awesome, thank you for that link. I should have guessed this was a thing but it hadn’t even occurred to me.

                And yeah, it is surprising that clang doesn’t treat mod power of 2 as a special case. It looks like I can’t type in code on mobile, does clang handle divide by power of 2 as a idiv or shift?

    • Ephera@lemmy.ml
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      5 months ago

      For large numbers, you might get a stack overflow. Depends on whether the compiler recognizes that it’s a tail recursion and then handles it appropriately.

      As for why Lemmy ignores single newlines, that’s because it uses Markdown for its comment syntax, which happens to handle newlines that way. If you want a single newline to display, you have to add two spaces at the end of the line.

      Here, you really would have wanted to use a code block, though, which you can create with backticks

      ```
      like
      so.
      ```

      Normally, this would display “like so.” in a monospace font and handle newlines as you expected:

      like
      so.
      
      • Buddahriffic@lemmy.world
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        5 months ago

        Just need to add some code that saves the base stack pointer, detects when the stack is about to run out, then saves the current number, resets the stack to the original pointer but now with the current number as x and continues on to fix the stack overflow issue. You don’t even have to restore the stack when it’s all unwinding!

        The integer overflow issue would be more complicated to solve except it isn’t really an issue because chopping off the upper bits doesn’t affect the eveness of a value.

        Oh and I thought of a quick way to verify the result of the algorithm. It should give the same result as this expression that you can use in your test suite:

        !(x & 1)
        

        Edit: um, new formatting problem… And that amp shows up in the edit box so it might even keep expanding.

    • Sotuanduso@lemm.ee
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      5 months ago

      Some quirk of this version of Markdown I think.
      Try putting two spaces at the end of a line before your single newline.

    • 1rre
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      5 months ago

      Markup languages.

      Which were done as such to allow people to write a sentence on each line in their editor, remember notepad etc. doesn’t wrap lines so you’ve got to scroll all the way over to read your lines.
      This became the de-facto way of formatting most things, and it’s easier to do newlines like that than using a br tag (and html tags generally) which are cringe af

      Note you can also do a smaller newline with two spaces at the end of the preceding line

    • 1rre
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      5 months ago

      Markup languages.

      Which were done as such to allow people to write a sentence on each line in their editor, remember notepad etc. doesn’t wrap lines so you’ve got to scroll all the way over to read your lines.
      This became the de-facto way of formatting most things, and it’s easier to do newlines like that than using a br tag (and html tags generally) which are cringe af

      Note you can also do a smaller newline with two spaces at the end of the preceding line

      • Buddahriffic@lemmy.world
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        5 months ago

        Notepad has had View->Word Wrap for a long time if you want soft word wrap instead of having to use a hard one.
        I didn’t know you could add two spaces to get a single newline to work though. Is that part of html or the formatting for this site?

        • 1rre
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          5 months ago

          Formatting for pretty much any forum…

          • Buddahriffic@lemmy.world
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            5 months ago

            The place the question is coming from is that I’ve implemented forum commenting from scratch before and it was trivial to get newlines behaving the same way in the edit box and when they are displayed and I’ve never seen the benefit of leaving it the way it is other than the case where a user uses hard newlines for word wrap instead of the soft wrap built into pretty much every browser’s edit box.

            • 1rre
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              5 months ago

              Yeah, in fact it’s actually easier, but it’s also just not desired behaviour.

              If you want a wysiwyg editor, feel free to implement it as an alternative setting, or it may even already exist, but forums populated by nerds have markdown for a very long time because it works well, is faster and more convenient once you know what you’re doing with it and above all else the nerds (frankly rightly) they get mad when you take it away, see how much hate Confluence gets for example.

              • Buddahriffic@lemmy.world
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                5 months ago

                I’m still mostly just confused as to what the use case is for that newline thing specifically. I get the idea behind a plaintext editor that can handle more complex text formatting (and get frustrated a lot with editors that try to guess what formatting I want as a type), but I don’t get why anyone would champion “I want to be able to hit enter as I’m inputting text without that showing up in the final output”. Is that just the way it behaves because that’s how it behaved in the past and people are used to it or is there a use case (or set of use cases) where this behaviour is desirable?