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  4. It's Primes as far as the eye can see!

It's Primes as far as the eye can see!

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  • OriginalGriffO OriginalGriff

    This is the whole of a would-be Tip submitted today:

    public class Class1
    {
    static void Main(string[] args)
    {
    Console.WriteLine("Enter a Number");
    int num = int.Parse(Console.ReadLine());
    for (int i = 1; i <=num ; i++)
    {
    if(i==2)
    Console.WriteLine(2);

                if (i % 2 != 0)
                {
                    Console.WriteLine(i);
                }
            }
    
         }
    }
    

    No text, no explanation - the author (I can only assume he works for Mindfire, it's about their level) clearly felt that it spoke for itself. And boy, does it ever! This, ladies-n-gentlemen, is a Prime Number generator according to the author. So...I tried it... According to this code, the prime numbers under 26 are:

    1
    2
    3
    5
    7
    9
    11
    13
    15
    17
    19
    21
    23
    25

    Now, call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3, and both 15 and 25 were divisible by 5... So which is wrong? The Code? Or the Laws of Mathematics? Only the author can tell... :laugh:

    Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

    P Offline
    P Offline
    PIEBALDconsult
    wrote on last edited by
    #12

    At least he used the % operator rather than implementing his own function.

    OriginalGriffO I 2 Replies Last reply
    0
    • P PIEBALDconsult

      At least he used the % operator rather than implementing his own function.

      OriginalGriffO Offline
      OriginalGriffO Offline
      OriginalGriff
      wrote on last edited by
      #13

      I suspect luck was involved.

      Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

      "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
      "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

      1 Reply Last reply
      0
      • P PIEBALDconsult

        At least he used the % operator rather than implementing his own function.

        I Offline
        I Offline
        Ian Shlasko
        wrote on last edited by
        #14

        Yeah, it could have been worse...

        public static bool SeeIfNumberIsOdd(int i)
        {
        for (int n = i; n > 0; n--)
        {
        if (n==1)
        return true;
        else if (n==2)
        return false;
        }
        return true;
        }

        That felt dirty to write... Ok, I probably could have made it a LITTLE worse... Maybe O(n^2), but that might be gratuitous.

        Proud to have finally moved to the A-Ark. Which one are you in?
        Author of the Guardians Saga (Sci-Fi/Fantasy novels)

        P 1 Reply Last reply
        0
        • I Ian Shlasko

          Yeah, it could have been worse...

          public static bool SeeIfNumberIsOdd(int i)
          {
          for (int n = i; n > 0; n--)
          {
          if (n==1)
          return true;
          else if (n==2)
          return false;
          }
          return true;
          }

          That felt dirty to write... Ok, I probably could have made it a LITTLE worse... Maybe O(n^2), but that might be gratuitous.

          Proud to have finally moved to the A-Ark. Which one are you in?
          Author of the Guardians Saga (Sci-Fi/Fantasy novels)

          P Offline
          P Offline
          PIEBALDconsult
          wrote on last edited by
          #15

          See the mod function in here: http://www.codeproject.com/script/Articles/ArticleVersion.aspx?aid=830657[^]

          I 1 Reply Last reply
          0
          • P PIEBALDconsult

            See the mod function in here: http://www.codeproject.com/script/Articles/ArticleVersion.aspx?aid=830657[^]

            I Offline
            I Offline
            Ian Shlasko
            wrote on last edited by
            #16

            Bah, I can do better than that!

            //TODO: Remove all comments before publishing. Real programmers don't need comments!
            public function SuperMod(int n, int o) // o is a great variable, because it looks like a zero
            {
            int p = o; //Shorter variable names make the code run faster!
            loopy: //Labels make me feel young again!
            while (p < n) p += o;
            if (p < n) goto loopy; //Just in case the compiler makes a mistake
            int answer = p - n;
            return answer;
            }

            Ok, I think that's about as bad as I can make it, and though I didn't test it at all (Honestly, I think the compiler would come to life and slit my throat for even trying to execute this monstrosity), that should technically give the right answer... Unless 'o' is negative or zero, but validating parameters is so 20th century...

            Proud to have finally moved to the A-Ark. Which one are you in?
            Author of the Guardians Saga (Sci-Fi/Fantasy novels)

            P B 2 Replies Last reply
            0
            • I Ian Shlasko

              Bah, I can do better than that!

              //TODO: Remove all comments before publishing. Real programmers don't need comments!
              public function SuperMod(int n, int o) // o is a great variable, because it looks like a zero
              {
              int p = o; //Shorter variable names make the code run faster!
              loopy: //Labels make me feel young again!
              while (p < n) p += o;
              if (p < n) goto loopy; //Just in case the compiler makes a mistake
              int answer = p - n;
              return answer;
              }

              Ok, I think that's about as bad as I can make it, and though I didn't test it at all (Honestly, I think the compiler would come to life and slit my throat for even trying to execute this monstrosity), that should technically give the right answer... Unless 'o' is negative or zero, but validating parameters is so 20th century...

              Proud to have finally moved to the A-Ark. Which one are you in?
              Author of the Guardians Saga (Sci-Fi/Fantasy novels)

              P Offline
              P Offline
              PIEBALDconsult
              wrote on last edited by
              #17

              Ian Shlasko wrote:

              give the right an answer

              FTFY

              I 1 Reply Last reply
              0
              • OriginalGriffO OriginalGriff

                newton.saber wrote:

                it's a puzzle for you.

                Not really: there are an infinite quantity of each. The way we define "more", "less", and "equal" for infinite quantities is as follows. For two collections A and B (say A are the even numbers and B are the odd numbers) we say that If you can associate every item in A with a unique item in B, and vice versa, then A and B are the same size. If you can associate every item in A with a unique item in B, but not vice versa, then B is bigger than A. If you can associate every item in B with a unique item in A, but not vice versa, then A is bigger than B. In this case you can associate every even number n with the odd number n+1, and you can associate every odd number m with the even number m−1 (assuming 0 is even) so therefore there are just as many odd numbers as even numbers.

                Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                N Offline
                N Offline
                newton saber
                wrote on last edited by
                #18

                This is terribly incorrect, because I stopped counting on an odd number, so there are more odd numbers than even. Thank you for your input. :D

                P 1 Reply Last reply
                0
                • P PIEBALDconsult

                  newton.saber wrote:

                  All odd numbers are prime, right?

                  No, primes aren't just any odd number.

                  N Offline
                  N Offline
                  newton saber
                  wrote on last edited by
                  #19

                  PIEBALDconsult wrote:

                  No, primes aren't just any odd number.

                  Of course they are. It's ridiculous to think that they aren't.

                  1 Reply Last reply
                  0
                  • OriginalGriffO OriginalGriff

                    This is the whole of a would-be Tip submitted today:

                    public class Class1
                    {
                    static void Main(string[] args)
                    {
                    Console.WriteLine("Enter a Number");
                    int num = int.Parse(Console.ReadLine());
                    for (int i = 1; i <=num ; i++)
                    {
                    if(i==2)
                    Console.WriteLine(2);

                                if (i % 2 != 0)
                                {
                                    Console.WriteLine(i);
                                }
                            }
                    
                         }
                    }
                    

                    No text, no explanation - the author (I can only assume he works for Mindfire, it's about their level) clearly felt that it spoke for itself. And boy, does it ever! This, ladies-n-gentlemen, is a Prime Number generator according to the author. So...I tried it... According to this code, the prime numbers under 26 are:

                    1
                    2
                    3
                    5
                    7
                    9
                    11
                    13
                    15
                    17
                    19
                    21
                    23
                    25

                    Now, call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3, and both 15 and 25 were divisible by 5... So which is wrong? The Code? Or the Laws of Mathematics? Only the author can tell... :laugh:

                    Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                    P Offline
                    P Offline
                    PhilLenoir
                    wrote on last edited by
                    #20

                    That's odd!

                    Life is like a s**t sandwich; the more bread you have, the less s**t you eat.

                    1 Reply Last reply
                    0
                    • OriginalGriffO OriginalGriff

                      This is the whole of a would-be Tip submitted today:

                      public class Class1
                      {
                      static void Main(string[] args)
                      {
                      Console.WriteLine("Enter a Number");
                      int num = int.Parse(Console.ReadLine());
                      for (int i = 1; i <=num ; i++)
                      {
                      if(i==2)
                      Console.WriteLine(2);

                                  if (i % 2 != 0)
                                  {
                                      Console.WriteLine(i);
                                  }
                              }
                      
                           }
                      }
                      

                      No text, no explanation - the author (I can only assume he works for Mindfire, it's about their level) clearly felt that it spoke for itself. And boy, does it ever! This, ladies-n-gentlemen, is a Prime Number generator according to the author. So...I tried it... According to this code, the prime numbers under 26 are:

                      1
                      2
                      3
                      5
                      7
                      9
                      11
                      13
                      15
                      17
                      19
                      21
                      23
                      25

                      Now, call me old fashioned, but in my day, 9, 15 and 21 were divisible by 3, and both 15 and 25 were divisible by 5... So which is wrong? The Code? Or the Laws of Mathematics? Only the author can tell... :laugh:

                      Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                      P Offline
                      P Offline
                      PIEBALDconsult
                      wrote on last edited by
                      #21

                      http://www.codeproject.com/Lounge.aspx?msg=85311#xx85311xx[^] http://www.codeproject.com/search.aspx?q=prime+number+error&categoryid=f1_1159_[^]

                      1 Reply Last reply
                      0
                      • D DaveAuld

                        RyanDev wrote:

                        but that's also back when Pluto was a planet

                        There was a thing on the telly recently that stated it had been voted back in as a planet.

                        Dave Find Me On:Web|Facebook|Twitter|LinkedIn Folding Stats: Team CodeProject

                        P Offline
                        P Offline
                        PhilLenoir
                        wrote on last edited by
                        #22

                        That's democracy for you!

                        Life is like a s**t sandwich; the more bread you have, the less s**t you eat.

                        1 Reply Last reply
                        0
                        • P PIEBALDconsult

                          Ian Shlasko wrote:

                          give the right an answer

                          FTFY

                          I Offline
                          I Offline
                          Ian Shlasko
                          wrote on last edited by
                          #23

                          Heh, yeah, you're right... It needs to be n+o-p... But hey, what's the point of testing when you're trying to write the worst code possible? (Still haven't tested... I was going to, but the compiler pulled a knife on me and said some very non-KSS things would happen if I tried)

                          Proud to have finally moved to the A-Ark. Which one are you in?
                          Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                          1 Reply Last reply
                          0
                          • I Ian Shlasko

                            Bah, I can do better than that!

                            //TODO: Remove all comments before publishing. Real programmers don't need comments!
                            public function SuperMod(int n, int o) // o is a great variable, because it looks like a zero
                            {
                            int p = o; //Shorter variable names make the code run faster!
                            loopy: //Labels make me feel young again!
                            while (p < n) p += o;
                            if (p < n) goto loopy; //Just in case the compiler makes a mistake
                            int answer = p - n;
                            return answer;
                            }

                            Ok, I think that's about as bad as I can make it, and though I didn't test it at all (Honestly, I think the compiler would come to life and slit my throat for even trying to execute this monstrosity), that should technically give the right answer... Unless 'o' is negative or zero, but validating parameters is so 20th century...

                            Proud to have finally moved to the A-Ark. Which one are you in?
                            Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                            B Offline
                            B Offline
                            Bert Mitton
                            wrote on last edited by
                            #24

                            Cut and pasted ! :laugh:

                            I 1 Reply Last reply
                            0
                            • B Bert Mitton

                              Cut and pasted ! :laugh:

                              I Offline
                              I Offline
                              Ian Shlasko
                              wrote on last edited by
                              #25

                              Ok, but if you're gonna use that code, make sure to either fix the bug, or... uh... only test with (4,2).

                              Proud to have finally moved to the A-Ark. Which one are you in?
                              Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                              B 1 Reply Last reply
                              0
                              • N newton saber

                                This is terribly incorrect, because I stopped counting on an odd number, so there are more odd numbers than even. Thank you for your input. :D

                                P Offline
                                P Offline
                                PIEBALDconsult
                                wrote on last edited by
                                #26

                                You might get a more accurate result if you start at infinity and count backward.

                                N 1 Reply Last reply
                                0
                                • P PIEBALDconsult

                                  You might get a more accurate result if you start at infinity and count backward.

                                  N Offline
                                  N Offline
                                  newton saber
                                  wrote on last edited by
                                  #27

                                  PIEBALDconsult wrote:

                                  You might get a more accurate result if you start at infinity and count backward

                                  Great idea. I'm working on this now. :D

                                  OriginalGriffO 1 Reply Last reply
                                  0
                                  • D DaveAuld

                                    RyanDev wrote:

                                    but that's also back when Pluto was a planet

                                    There was a thing on the telly recently that stated it had been voted back in as a planet.

                                    Dave Find Me On:Web|Facebook|Twitter|LinkedIn Folding Stats: Team CodeProject

                                    N Offline
                                    N Offline
                                    newton saber
                                    wrote on last edited by
                                    #28

                                    DaveAuld wrote:

                                    it had been voted back in as a planet

                                    That is such a coincidence because I've just been voted in as a planet too. Very cool. I hope to be voted in as a Sun one day so I can go by the name Apollo. It's such a cool name. Plus then all you people will have to rotate around me and I'll be the center of your Universe. Yes, the sun is the center of the Universe. I pre-emptively struck on your future humor that I didn't know that the sun was the center of a solar system. Wham!

                                    D 1 Reply Last reply
                                    0
                                    • I Ian Shlasko

                                      Ok, but if you're gonna use that code, make sure to either fix the bug, or... uh... only test with (4,2).

                                      Proud to have finally moved to the A-Ark. Which one are you in?
                                      Author of the Guardians Saga (Sci-Fi/Fantasy novels)

                                      B Offline
                                      B Offline
                                      Bert Mitton
                                      wrote on last edited by
                                      #29

                                      Testing ? If it fails, that's what Q&A is for. I don't need to test. :-D

                                      1 Reply Last reply
                                      0
                                      • N newton saber

                                        PIEBALDconsult wrote:

                                        You might get a more accurate result if you start at infinity and count backward

                                        Great idea. I'm working on this now. :D

                                        OriginalGriffO Offline
                                        OriginalGriffO Offline
                                        OriginalGriff
                                        wrote on last edited by
                                        #30

                                        Chuck Norris already did it. Twice.

                                        Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                                        "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
                                        "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

                                        N 1 Reply Last reply
                                        0
                                        • N newton saber

                                          DaveAuld wrote:

                                          it had been voted back in as a planet

                                          That is such a coincidence because I've just been voted in as a planet too. Very cool. I hope to be voted in as a Sun one day so I can go by the name Apollo. It's such a cool name. Plus then all you people will have to rotate around me and I'll be the center of your Universe. Yes, the sun is the center of the Universe. I pre-emptively struck on your future humor that I didn't know that the sun was the center of a solar system. Wham!

                                          D Offline
                                          D Offline
                                          DaveAuld
                                          wrote on last edited by
                                          #31

                                          back.....away.....from.....the.....keyboard......:~

                                          Dave Find Me On:Web|Facebook|Twitter|LinkedIn Folding Stats: Team CodeProject

                                          I 1 Reply Last reply
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