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Yet another fun C-puzzle

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  • D David Stone

    Very nice. :) I hadn't even considered using function pointers. I was talking to Nish and suggested one printf with 100 digits and 100 linebreaks. ;)


    [Cheshire] I can't afford those plastic things to cover the electric sockets so I just draw bunny faces on the electric outlets to scare the kids away from them... [RLtim] Newsflash! Kids aren't afraid of bunnies. [Cheshire] Oh they will be... -Bash.org

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    Nish Nishant
    wrote on last edited by
    #12

    David Stone wrote: I was talking to Nish and suggested one printf with 100 digits and 100 linebreaks. Guys, it's okay, David is from Southern California - so as I said, it's quite okay :rolleyes:

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    • R Russell Morris

      Hmm...

      static int i=1;
      typedef void (*fn) ();
      fn pfn[2];

      void print_i(void)
      {
      printf("%d\n",i);
      // Not a conditional! :)
      // i++ / 100 will evaluate to 0 until i has reached 100
      (pfn[i++ / 100])();
      }

      void go_bye_bye()
      {
      exit(0);
      }

      void main(void)
      {
      pfn[0] = &print_i;
      pfn[1] = &go_bye_bye;

      (pfn\[0\])();
      

      }

      -- Russell Morris "So, broccoli, mother says you're good for me... but I'm afraid I'm no good for you!" - Stewy

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      Ryan Binns
      wrote on last edited by
      #13

      Mine was pretty similar except it doesn't use globals and uses a double-not rather than / 100 :)

      #include <stdlib.h>
      #include <stdio.h>

      typedef void (*funcptr)(int);

      funcptr buf[2];

      void count(int num)
      {
      printf("%d\n", 100-num);
      (*buf[!!num])(num-1);
      }

      int main()
      {
      buf[0] = exit;
      buf[1] = count;
      count(99);
      }

      Ryan

      "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

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      • C Chris Maunder

        Can we print more than 100? Does the program have to terminate elegantly? I came up with a quick solution but it ain't exactly pretty :D cheers, Chris Maunder

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        Nish Nishant
        wrote on last edited by
        #14

        Chris Maunder wrote: Can we print more than 100? Does the program have to terminate elegantly? I came up with a quick solution but it ain't exactly pretty :-D

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        • R Ryan Binns

          Mine was pretty similar except it doesn't use globals and uses a double-not rather than / 100 :)

          #include <stdlib.h>
          #include <stdio.h>

          typedef void (*funcptr)(int);

          funcptr buf[2];

          void count(int num)
          {
          printf("%d\n", 100-num);
          (*buf[!!num])(num-1);
          }

          int main()
          {
          buf[0] = exit;
          buf[1] = count;
          count(99);
          }

          Ryan

          "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

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          Nish Nishant
          wrote on last edited by
          #15

          *Applause* The double not was pretty cool - more elegant than Russel's division - and a lot more neater than my comparision operator :-) Nish

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          • N Nish Nishant

            *Applause* The double not was pretty cool - more elegant than Russel's division - and a lot more neater than my comparision operator :-) Nish

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            Nish Nishant
            wrote on last edited by
            #16

            Ryan Russel still wins though - 1) he posted it first 2) he uses division which while inelegant is not a conditional expression, your double not (while elegant) is still a conditional expression (valid as the question only disallows conditional statements and expressions are not statements) Nish

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            • N Nish Nishant

              This question was asked in the Trivandrum Microsoft UG forums :- Using C, print 1-100 without using any loop or conditional statements? An answer was later posted in C++ (and the poster said that it was not possible without C++). Here's his C++ solution :-

              static int i=0;

              class ad
              {
              ad()
              {
              i++;
              cout << i;
              }
              }

              void main()
              {
              ad objad[100];
              }

              I spent a part of my Sunday evening wondering if it was possible in some alternative manner and found a solution. It shouldn't take you more than 15-20 minutes to think of it (assuming you haven't done this before). Let's see who gets there first (remember - no C++, no classes). Nish :-)

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              Vivek Rajan
              wrote on last edited by
              #17

              How about this int main(int ac, char ** av) { static int i=1; printf("%d ",i++); i%101&&main(0,0); }

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              • V Vivek Rajan

                How about this int main(int ac, char ** av) { static int i=1; printf("%d ",i++); i%101&&main(0,0); }

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                Nish Nishant
                wrote on last edited by
                #18

                Cool stuff, Vivek :-) Nish

                N 1 Reply Last reply
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                • N Nish Nishant

                  Cool stuff, Vivek :-) Nish

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                  Nish Nishant
                  wrote on last edited by
                  #19

                  Here's an improvement (LOC reduced anyway)

                  int main(int ac, char ** av)
                  {
                  printf("%d ",101-ac,(ac%100)&&main(ac+1,0));
                  }

                  Run the app without arguments (first time ac will be 1) Nish

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                  • N Nish Nishant

                    BTW 100 printfs don't count :rolleyes:

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                    GizzoF
                    wrote on last edited by
                    #20

                    Nishant S wrote: BTW 100 printfs don't count why not? It is a solution, isn't it?

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                    • N Nish Nishant

                      This question was asked in the Trivandrum Microsoft UG forums :- Using C, print 1-100 without using any loop or conditional statements? An answer was later posted in C++ (and the poster said that it was not possible without C++). Here's his C++ solution :-

                      static int i=0;

                      class ad
                      {
                      ad()
                      {
                      i++;
                      cout << i;
                      }
                      }

                      void main()
                      {
                      ad objad[100];
                      }

                      I spent a part of my Sunday evening wondering if it was possible in some alternative manner and found a solution. It shouldn't take you more than 15-20 minutes to think of it (assuming you haven't done this before). Let's see who gets there first (remember - no C++, no classes). Nish :-)

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                      Zdeslav Vojkovic
                      wrote on last edited by
                      #21

                      template <long val> void printfn() { std::cout << val << "\n"; printfn<val + 1>(); } template <> void printfn<100L>() { std::cout << "100\n"; } int main(int argc, char* argv[]) { printfn<1L>(); system("PAUSE"); return 0; } this works fine in VS.NET 2003 and gcc, but not with VC++ 6.0 which generates wrong specialization. i suppose that it also faster then previous solutions, since it is resolved in compile time.

                      N 1 Reply Last reply
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                      • Z Zdeslav Vojkovic

                        template <long val> void printfn() { std::cout << val << "\n"; printfn<val + 1>(); } template <> void printfn<100L>() { std::cout << "100\n"; } int main(int argc, char* argv[]) { printfn<1L>(); system("PAUSE"); return 0; } this works fine in VS.NET 2003 and gcc, but not with VC++ 6.0 which generates wrong specialization. i suppose that it also faster then previous solutions, since it is resolved in compile time.

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                        Nish Nishant
                        wrote on last edited by
                        #22

                        Good code, but C does not support templates :-) Nish

                        Z 1 Reply Last reply
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                        • N Nish Nishant

                          Good code, but C does not support templates :-) Nish

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                          Zdeslav Vojkovic
                          wrote on last edited by
                          #23

                          :-O i got carried away by this line from your original post: "An answer was later posted in C++ (and the poster said that it was not possible without C++)."

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                          0
                          • N Nish Nishant

                            This question was asked in the Trivandrum Microsoft UG forums :- Using C, print 1-100 without using any loop or conditional statements? An answer was later posted in C++ (and the poster said that it was not possible without C++). Here's his C++ solution :-

                            static int i=0;

                            class ad
                            {
                            ad()
                            {
                            i++;
                            cout << i;
                            }
                            }

                            void main()
                            {
                            ad objad[100];
                            }

                            I spent a part of my Sunday evening wondering if it was possible in some alternative manner and found a solution. It shouldn't take you more than 15-20 minutes to think of it (assuming you haven't done this before). Let's see who gets there first (remember - no C++, no classes). Nish :-)

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                            U Offline
                            utsav_verma
                            wrote on last edited by
                            #24

                            assuming that if also doesnt matter n yeah also mind that i m writing code directly here, neither compiled nor checked for output - int main(int x) { printf("%d",x); if(x<100) main(++x); } program is expected to run from command prompt as filename 0 what do u think?? UTSAV MCA final yr

                            N 2 Replies Last reply
                            0
                            • N Nish Nishant

                              This question was asked in the Trivandrum Microsoft UG forums :- Using C, print 1-100 without using any loop or conditional statements? An answer was later posted in C++ (and the poster said that it was not possible without C++). Here's his C++ solution :-

                              static int i=0;

                              class ad
                              {
                              ad()
                              {
                              i++;
                              cout << i;
                              }
                              }

                              void main()
                              {
                              ad objad[100];
                              }

                              I spent a part of my Sunday evening wondering if it was possible in some alternative manner and found a solution. It shouldn't take you more than 15-20 minutes to think of it (assuming you haven't done this before). Let's see who gets there first (remember - no C++, no classes). Nish :-)

                              J Offline
                              J Offline
                              Jason Pease
                              wrote on last edited by
                              #25

                              Does this count? void main(){ char buffer[8] strcpy(buffer,"1-100"); cout << buffer << endl; } Jason

                              N 1 Reply Last reply
                              0
                              • U utsav_verma

                                assuming that if also doesnt matter n yeah also mind that i m writing code directly here, neither compiled nor checked for output - int main(int x) { printf("%d",x); if(x<100) main(++x); } program is expected to run from command prompt as filename 0 what do u think?? UTSAV MCA final yr

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                                Nish Nishant
                                wrote on last edited by
                                #26

                                if is a conditional statement - not allowed.

                                1 Reply Last reply
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                                • N Nish Nishant

                                  BTW 100 printfs don't count :rolleyes:

                                  D Offline
                                  D Offline
                                  DavidNohejl
                                  wrote on last edited by
                                  #27

                                  Does one printf with 100 numbers count? :) sorry if this question was already asked, I didn't look at other posts... David Never forget: "Stay kul and happy" (I.A.)
                                  David's thoughts / dnhsoftware.org / MyHTMLTidy

                                  1 Reply Last reply
                                  0
                                  • U utsav_verma

                                    assuming that if also doesnt matter n yeah also mind that i m writing code directly here, neither compiled nor checked for output - int main(int x) { printf("%d",x); if(x<100) main(++x); } program is expected to run from command prompt as filename 0 what do u think?? UTSAV MCA final yr

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                                    N Offline
                                    Nish Nishant
                                    wrote on last edited by
                                    #28

                                    utsav_verma wrote: int main(int x) { printf("%d",x); if(x<100) main(++x); } program is expected to run from command prompt as filename 0 what do u think?? In addition to "if" being conditional (and therefore you break the rules), there are other bugs in your code. The first argument to main is the number of arguments and if you invoke the prog as "filename 0" as you say, this will be equal to 2 (including the file name). Thus your prog starts printing from 2. 2nd issue is that main should ideally take 2 arguments (though most compilers will let your code compile).

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                                    • J Jason Pease

                                      Does this count? void main(){ char buffer[8] strcpy(buffer,"1-100"); cout << buffer << endl; } Jason

                                      N Offline
                                      N Offline
                                      Nish Nishant
                                      wrote on last edited by
                                      #29

                                      Jason Pease wrote: Does this count? void main(){ char buffer[8] strcpy(buffer,"1-100"); cout << buffer << endl; } :rolleyes:

                                      1 Reply Last reply
                                      0
                                      • N Nish Nishant

                                        This question was asked in the Trivandrum Microsoft UG forums :- Using C, print 1-100 without using any loop or conditional statements? An answer was later posted in C++ (and the poster said that it was not possible without C++). Here's his C++ solution :-

                                        static int i=0;

                                        class ad
                                        {
                                        ad()
                                        {
                                        i++;
                                        cout << i;
                                        }
                                        }

                                        void main()
                                        {
                                        ad objad[100];
                                        }

                                        I spent a part of my Sunday evening wondering if it was possible in some alternative manner and found a solution. It shouldn't take you more than 15-20 minutes to think of it (assuming you haven't done this before). Let's see who gets there first (remember - no C++, no classes). Nish :-)

                                        D Offline
                                        D Offline
                                        DavidNohejl
                                        wrote on last edited by
                                        #30

                                        #define max 100 static int i = 1; bool Print() { print(i++); return ((max - i) && Print()) }
                                        Since we cant use iterative approarch (loops) let's make it recursive. We can't use condition statement (if) so let's use short-circuit expression :) yeah quite late but I had to go visit lectures :( I've solved it on the way there :) David Never forget: "Stay kul and happy" (I.A.)
                                        David's thoughts / dnhsoftware.org / MyHTMLTidy

                                        M 1 Reply Last reply
                                        0
                                        • D DavidNohejl

                                          #define max 100 static int i = 1; bool Print() { print(i++); return ((max - i) && Print()) }
                                          Since we cant use iterative approarch (loops) let's make it recursive. We can't use condition statement (if) so let's use short-circuit expression :) yeah quite late but I had to go visit lectures :( I've solved it on the way there :) David Never forget: "Stay kul and happy" (I.A.)
                                          David's thoughts / dnhsoftware.org / MyHTMLTidy

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                                          M Offline
                                          mracoder
                                          wrote on last edited by
                                          #31

                                          Well thank you wery much David for enlightening me with your approach to the problem!!! - Finally I've got it what the last line (like in Vivek Ryan's code, for example) actually does! I persume, now, that C doesn't run/check the second argument of AND(&&) when the first is already evaluated as "bogus". Nice trick, must say! MY GREETINGS TO ALL by mladjan

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