Iterative Fibonacci sequence











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I implemented a function that prints all the numbers from the Fibonacci sequence until max_num. The minimum value allowed is 0 (so, fib(0) prints 1). It works until 92, and I want to know how to improve the code, in general.



void fib(unsigned int max_num)
{
unsigned long fib_num = 1;
unsigned long fib_temp = 0;
size_t count = 0;

if (max_num < 0)
{
fprintf(stderr, "Please, enter a non-negative numbern");
return;
}

for (; count <= max_num; count++)
{
printf("%lun", fib_num);
fib_num += fib_temp;
fib_temp = fib_num - fib_temp;
}
}









share|improve this question


























    up vote
    3
    down vote

    favorite












    I implemented a function that prints all the numbers from the Fibonacci sequence until max_num. The minimum value allowed is 0 (so, fib(0) prints 1). It works until 92, and I want to know how to improve the code, in general.



    void fib(unsigned int max_num)
    {
    unsigned long fib_num = 1;
    unsigned long fib_temp = 0;
    size_t count = 0;

    if (max_num < 0)
    {
    fprintf(stderr, "Please, enter a non-negative numbern");
    return;
    }

    for (; count <= max_num; count++)
    {
    printf("%lun", fib_num);
    fib_num += fib_temp;
    fib_temp = fib_num - fib_temp;
    }
    }









    share|improve this question
























      up vote
      3
      down vote

      favorite









      up vote
      3
      down vote

      favorite











      I implemented a function that prints all the numbers from the Fibonacci sequence until max_num. The minimum value allowed is 0 (so, fib(0) prints 1). It works until 92, and I want to know how to improve the code, in general.



      void fib(unsigned int max_num)
      {
      unsigned long fib_num = 1;
      unsigned long fib_temp = 0;
      size_t count = 0;

      if (max_num < 0)
      {
      fprintf(stderr, "Please, enter a non-negative numbern");
      return;
      }

      for (; count <= max_num; count++)
      {
      printf("%lun", fib_num);
      fib_num += fib_temp;
      fib_temp = fib_num - fib_temp;
      }
      }









      share|improve this question













      I implemented a function that prints all the numbers from the Fibonacci sequence until max_num. The minimum value allowed is 0 (so, fib(0) prints 1). It works until 92, and I want to know how to improve the code, in general.



      void fib(unsigned int max_num)
      {
      unsigned long fib_num = 1;
      unsigned long fib_temp = 0;
      size_t count = 0;

      if (max_num < 0)
      {
      fprintf(stderr, "Please, enter a non-negative numbern");
      return;
      }

      for (; count <= max_num; count++)
      {
      printf("%lun", fib_num);
      fib_num += fib_temp;
      fib_temp = fib_num - fib_temp;
      }
      }






      beginner c fibonacci-sequence






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      share|improve this question




      share|improve this question










      asked Aug 22 '16 at 21:40









      Lúcio Cardoso

      447314




      447314






















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          6
          down vote



          accepted










          Consider documenting this function with something like doxygen. At a quick glance, your function can be interpreted two different ways: Print out fib(0), fib(1), ..., or print out all Fibonacci numbers less than or equal to max_num. Documentation will clarify that.



          max_num will never be negative. It is defined as an unsigned int, which means it can never hold a negative value. So this:



          if (max_num < 0)
          {
          fprintf(stderr, "Please, enter a non-negative numbern");
          return;
          }


          will never happen. (Try calling fib(-2), see what happens)



          (Optional) Put size_t count = 0 inside the loop if you can? (You may have to add -std=c99 or something like that to make it work)



          for (size_t count = 0; count <= max_num; count++)
          {
          printf("%lun", fib_num);
          fib_num += fib_temp;
          fib_temp = fib_num - fib_temp;
          }





          share|improve this answer























          • Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
            – Lúcio Cardoso
            Aug 23 '16 at 0:33






          • 1




            It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
            – Dair
            Aug 23 '16 at 0:50












          • For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
            – Dair
            Aug 23 '16 at 0:53










          • @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
            – larkey
            Aug 24 '16 at 10:23











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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          6
          down vote



          accepted










          Consider documenting this function with something like doxygen. At a quick glance, your function can be interpreted two different ways: Print out fib(0), fib(1), ..., or print out all Fibonacci numbers less than or equal to max_num. Documentation will clarify that.



          max_num will never be negative. It is defined as an unsigned int, which means it can never hold a negative value. So this:



          if (max_num < 0)
          {
          fprintf(stderr, "Please, enter a non-negative numbern");
          return;
          }


          will never happen. (Try calling fib(-2), see what happens)



          (Optional) Put size_t count = 0 inside the loop if you can? (You may have to add -std=c99 or something like that to make it work)



          for (size_t count = 0; count <= max_num; count++)
          {
          printf("%lun", fib_num);
          fib_num += fib_temp;
          fib_temp = fib_num - fib_temp;
          }





          share|improve this answer























          • Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
            – Lúcio Cardoso
            Aug 23 '16 at 0:33






          • 1




            It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
            – Dair
            Aug 23 '16 at 0:50












          • For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
            – Dair
            Aug 23 '16 at 0:53










          • @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
            – larkey
            Aug 24 '16 at 10:23















          up vote
          6
          down vote



          accepted










          Consider documenting this function with something like doxygen. At a quick glance, your function can be interpreted two different ways: Print out fib(0), fib(1), ..., or print out all Fibonacci numbers less than or equal to max_num. Documentation will clarify that.



          max_num will never be negative. It is defined as an unsigned int, which means it can never hold a negative value. So this:



          if (max_num < 0)
          {
          fprintf(stderr, "Please, enter a non-negative numbern");
          return;
          }


          will never happen. (Try calling fib(-2), see what happens)



          (Optional) Put size_t count = 0 inside the loop if you can? (You may have to add -std=c99 or something like that to make it work)



          for (size_t count = 0; count <= max_num; count++)
          {
          printf("%lun", fib_num);
          fib_num += fib_temp;
          fib_temp = fib_num - fib_temp;
          }





          share|improve this answer























          • Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
            – Lúcio Cardoso
            Aug 23 '16 at 0:33






          • 1




            It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
            – Dair
            Aug 23 '16 at 0:50












          • For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
            – Dair
            Aug 23 '16 at 0:53










          • @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
            – larkey
            Aug 24 '16 at 10:23













          up vote
          6
          down vote



          accepted







          up vote
          6
          down vote



          accepted






          Consider documenting this function with something like doxygen. At a quick glance, your function can be interpreted two different ways: Print out fib(0), fib(1), ..., or print out all Fibonacci numbers less than or equal to max_num. Documentation will clarify that.



          max_num will never be negative. It is defined as an unsigned int, which means it can never hold a negative value. So this:



          if (max_num < 0)
          {
          fprintf(stderr, "Please, enter a non-negative numbern");
          return;
          }


          will never happen. (Try calling fib(-2), see what happens)



          (Optional) Put size_t count = 0 inside the loop if you can? (You may have to add -std=c99 or something like that to make it work)



          for (size_t count = 0; count <= max_num; count++)
          {
          printf("%lun", fib_num);
          fib_num += fib_temp;
          fib_temp = fib_num - fib_temp;
          }





          share|improve this answer














          Consider documenting this function with something like doxygen. At a quick glance, your function can be interpreted two different ways: Print out fib(0), fib(1), ..., or print out all Fibonacci numbers less than or equal to max_num. Documentation will clarify that.



          max_num will never be negative. It is defined as an unsigned int, which means it can never hold a negative value. So this:



          if (max_num < 0)
          {
          fprintf(stderr, "Please, enter a non-negative numbern");
          return;
          }


          will never happen. (Try calling fib(-2), see what happens)



          (Optional) Put size_t count = 0 inside the loop if you can? (You may have to add -std=c99 or something like that to make it work)



          for (size_t count = 0; count <= max_num; count++)
          {
          printf("%lun", fib_num);
          fib_num += fib_temp;
          fib_temp = fib_num - fib_temp;
          }






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 7 mins ago









          albert

          1071




          1071










          answered Aug 22 '16 at 23:18









          Dair

          4,417729




          4,417729












          • Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
            – Lúcio Cardoso
            Aug 23 '16 at 0:33






          • 1




            It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
            – Dair
            Aug 23 '16 at 0:50












          • For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
            – Dair
            Aug 23 '16 at 0:53










          • @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
            – larkey
            Aug 24 '16 at 10:23


















          • Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
            – Lúcio Cardoso
            Aug 23 '16 at 0:33






          • 1




            It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
            – Dair
            Aug 23 '16 at 0:50












          • For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
            – Dair
            Aug 23 '16 at 0:53










          • @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
            – larkey
            Aug 24 '16 at 10:23
















          Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
          – Lúcio Cardoso
          Aug 23 '16 at 0:33




          Thanks a lot for the answer! I heard some people saying I should stick to the c89 mode. In your opinion, which one is the best?
          – Lúcio Cardoso
          Aug 23 '16 at 0:33




          1




          1




          It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
          – Dair
          Aug 23 '16 at 0:50






          It has a lot to do with how much of the market supports the language... It may have been at the time a better idea to use C89 over C99 because very few compilers supported C99. This isn't true anymore. It might even be better to use C11. (Which I believe is -std=c11). A large part is do you need to support C89? C99? If not, I would just do C99, the for-loop syntax for C89 is particularly annoying to me.
          – Dair
          Aug 23 '16 at 0:50














          For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
          – Dair
          Aug 23 '16 at 0:53




          For reference there are answers here: stackoverflow.com/a/11926008/667648 That coincide with my comment.
          – Dair
          Aug 23 '16 at 0:53












          @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
          – larkey
          Aug 24 '16 at 10:23




          @LúcioCardoso The only more or less relevant compiler not supporting C99 is VS C compiler afaik. But C is mostly broken under Windows, similar to OpenGL. It works, with a few quirks, but it's not for serious development.
          – larkey
          Aug 24 '16 at 10:23


















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