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  4. Ever heard of casting?

Ever heard of casting?

Scheduled Pinned Locked Moved The Weird and The Wonderful
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  • C chevu

    it might have a syntax error but you can do it this way.. you can refer algorithm by corman... n compare to given algo for (int i = 0; i < 18; i++) { tenE18 *= 10; } this one will run for 18times.. for debuging also you have to go through this loop 18 times... then how can you say algo i gave takes more time to debug.. complexity of given algo is O(n) and complexity of algo i gave is O(lg(n))....

    modified on Wednesday, March 3, 2010 10:37 PM

    L Offline
    L Offline
    Luc Pattyn
    wrote on last edited by
    #16

    chevu wrote:

    how can you say algo i gave takes more time to debug.. complexity of given algo is O(n)

    O(n) and O(lg(n)) apply to execution time, not debugging time. There are no formulas for debugging time; it depends on number of statements, decision points, readability of code, and initial number of bugs. Your code has more than 5 bugs, it will take you lots of time to find all of them. I suggest you try and fix and run it until the result is correct. :|

    Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


    I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


    J 1 Reply Last reply
    0
    • J johannesnestler

      yea - it was even hard for me to check his crazy code - lol. There is some resistence to execute such a thing - :)

      C Offline
      C Offline
      chevu
      wrote on last edited by
      #17

      sorry i messed up with code... This one is correct code

      decimal res = 10;
      decimal multi = 10;
      decimal rem = 1;
      int pow = 18;//For pow 0 you can directly return with 0

      while(pow > 1)
      {
      res *= res;
      rem *= (pow%2)? multi:1;
      pow /= 2;
      }
      res *= rem;

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      0
      • C chevu

        sorry i messed up with code... This one is correct code

        decimal res = 10;
        decimal multi = 10;
        decimal rem = 1;
        int pow = 18;//For pow 0 you can directly return with 0

        while(pow > 1)
        {
        res *= res;
        rem *= (pow%2)? multi:1;
        pow /= 2;
        }
        res *= rem;

        L Offline
        L Offline
        Luc Pattyn
        wrote on last edited by
        #18

        chevu wrote:

        This one is correct code

        wrong again: 1. the result for pow=18 is wrong. 2. pow=5 and pow=6 give the same result??? I think you have abundantly proven now that your code has high debugging complexity. :(

        Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


        I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


        C 1 Reply Last reply
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        • L Luc Pattyn

          chevu wrote:

          This one is correct code

          wrong again: 1. the result for pow=18 is wrong. 2. pow=5 and pow=6 give the same result??? I think you have abundantly proven now that your code has high debugging complexity. :(

          Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


          I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


          C Offline
          C Offline
          chevu
          wrote on last edited by
          #19

          sorry dude... i had really forget to check till 18... coz of odd even cases that code will fail... I knw you people are getting irritated by now, but you can check this code

          double pow(long long a, long long b)
          {
          if(b == 0)
          return 1.0;
          else if(b == 1)
          return a;
          else if(b%2 == 0)
          return pow(a*a,b/2);
          else
          return a* pow(a*a,b/2);
          }

          i have tested this code upto long long limits...

          S J 2 Replies Last reply
          0
          • C chevu

            sorry dude... i had really forget to check till 18... coz of odd even cases that code will fail... I knw you people are getting irritated by now, but you can check this code

            double pow(long long a, long long b)
            {
            if(b == 0)
            return 1.0;
            else if(b == 1)
            return a;
            else if(b%2 == 0)
            return pow(a*a,b/2);
            else
            return a* pow(a*a,b/2);
            }

            i have tested this code upto long long limits...

            S Offline
            S Offline
            Stanciu Vlad
            wrote on last edited by
            #20

            Recursive functions brings color in life :-D

            I have no smart signature yet...

            1 Reply Last reply
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            • C chevu

              sorry dude... i had really forget to check till 18... coz of odd even cases that code will fail... I knw you people are getting irritated by now, but you can check this code

              double pow(long long a, long long b)
              {
              if(b == 0)
              return 1.0;
              else if(b == 1)
              return a;
              else if(b%2 == 0)
              return pow(a*a,b/2);
              else
              return a* pow(a*a,b/2);
              }

              i have tested this code upto long long limits...

              J Offline
              J Offline
              J4amieC
              wrote on last edited by
              #21

              chevu wrote:

              long long a

              If I were a canadian, thats how I would describe this thread.

              modified on Thursday, March 4, 2010 8:11 AM

              C 1 Reply Last reply
              0
              • J J4amieC

                chevu wrote:

                long long a

                If I were a canadian, thats how I would describe this thread.

                modified on Thursday, March 4, 2010 8:11 AM

                C Offline
                C Offline
                chevu
                wrote on last edited by
                #22

                what kind of comment was that?

                J 1 Reply Last reply
                0
                • C chevu

                  what kind of comment was that?

                  J Offline
                  J Offline
                  J4amieC
                  wrote on last edited by
                  #23

                  Erm, a half-assed joke, you douche.

                  1 Reply Last reply
                  0
                  • L Luc Pattyn

                    chevu wrote:

                    how can you say algo i gave takes more time to debug.. complexity of given algo is O(n)

                    O(n) and O(lg(n)) apply to execution time, not debugging time. There are no formulas for debugging time; it depends on number of statements, decision points, readability of code, and initial number of bugs. Your code has more than 5 bugs, it will take you lots of time to find all of them. I suggest you try and fix and run it until the result is correct. :|

                    Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                    I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


                    J Offline
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                    johannesnestler
                    wrote on last edited by
                    #24

                    thank you for answering to chevu - he didn't get the hint - "debug time" :rose:

                    1 Reply Last reply
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                    • C chevu

                      sorry i messed up with code... This one is correct code

                      decimal res = 10;
                      decimal multi = 10;
                      decimal rem = 1;
                      int pow = 18;//For pow 0 you can directly return with 0

                      while(pow > 1)
                      {
                      res *= res;
                      rem *= (pow%2)? multi:1;
                      pow /= 2;
                      }
                      res *= rem;

                      L Offline
                      L Offline
                      Lost User
                      wrote on last edited by
                      #25

                      Here's how:

                          static decimal pow(decimal x, **u**int n)
                          {
                              decimal result = 1;
                              while (n > 0)
                              {
                                  if ((n & 1) == 1)
                                  {
                                      result \*= x;
                                  }
                                  n >>= 1;
                                  if (n == 0)
                                      break;   //not nice, but needed in case x\*x overflow on the last step
                                  x \*= x;
                              }
                              return result;
                          }
                      

                      Good luck! ok so it's not the best possible code, I just hacked it together, but it works (tested)

                      modified on Friday, March 5, 2010 11:40 AM

                      L 1 Reply Last reply
                      0
                      • L Lost User

                        Here's how:

                            static decimal pow(decimal x, **u**int n)
                            {
                                decimal result = 1;
                                while (n > 0)
                                {
                                    if ((n & 1) == 1)
                                    {
                                        result \*= x;
                                    }
                                    n >>= 1;
                                    if (n == 0)
                                        break;   //not nice, but needed in case x\*x overflow on the last step
                                    x \*= x;
                                }
                                return result;
                            }
                        

                        Good luck! ok so it's not the best possible code, I just hacked it together, but it works (tested)

                        modified on Friday, March 5, 2010 11:40 AM

                        L Offline
                        L Offline
                        Luc Pattyn
                        wrote on last edited by
                        #26

                        harold aptroot wrote:

                        (tested)

                        that is unacceptable. This is the Coding Horrors forum after all. You're expected to publish something that is completely wrong, yet claim it is correct. :)

                        Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                        I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


                        L 1 Reply Last reply
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                        • L Luc Pattyn

                          harold aptroot wrote:

                          (tested)

                          that is unacceptable. This is the Coding Horrors forum after all. You're expected to publish something that is completely wrong, yet claim it is correct. :)

                          Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                          I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


                          L Offline
                          L Offline
                          Lost User
                          wrote on last edited by
                          #27

                          Oops! Sorry :)

                          L 1 Reply Last reply
                          0
                          • L Lost User

                            Oops! Sorry :)

                            L Offline
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                            Luc Pattyn
                            wrote on last edited by
                            #28

                            No problem. Anyway, it fails for negative n. :)

                            Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                            I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


                            L 1 Reply Last reply
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                            • L Luc Pattyn

                              No problem. Anyway, it fails for negative n. :)

                              Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                              I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


                              L Offline
                              L Offline
                              Lost User
                              wrote on last edited by
                              #29

                              It's not supposed to work for negative n anyway

                              L 1 Reply Last reply
                              0
                              • L Lost User

                                It's not supposed to work for negative n anyway

                                L Offline
                                L Offline
                                Luc Pattyn
                                wrote on last edited by
                                #30

                                I didn't see any specs; you could have tested and thrown an InvalidArgumentException; or made the second parameter a uint. [EDIT]Negative exponents result in divisions, which for integers tend to yield either 0 or 1 depending on the value of a.[/EDIT] :)

                                Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                                I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


                                L 1 Reply Last reply
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                                • L Luc Pattyn

                                  I didn't see any specs; you could have tested and thrown an InvalidArgumentException; or made the second parameter a uint. [EDIT]Negative exponents result in divisions, which for integers tend to yield either 0 or 1 depending on the value of a.[/EDIT] :)

                                  Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]


                                  I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.


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                                  Lost User
                                  wrote on last edited by
                                  #31

                                  Is that really necessary..? Fortunately adding just 1 letter of code takes the problem away.

                                  1 Reply Last reply
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                                  • A ArchimaX

                                    This is an excerpt from some sample code provided in the documentation for an EFT interface

                                    decimal divider;
                                    // we need 10^18, but Math.Pow does not support decimal
                                    // types and decimal does not provide a power function
                                    divider = 10*10*10;
                                    divider = Decimal.Multiply(divider,10*10*10*10*10);
                                    divider = Decimal.Multiply(divider,10*10*10*10*10);
                                    divider = Decimal.Multiply(divider,10*10*10*10*10);

                                    Blows my mind :-)

                                    R Offline
                                    R Offline
                                    Rob Grainger
                                    wrote on last edited by
                                    #32

                                    Not sure a cast is the best approach here - decimal types are OK for currency and other situations where accuracy is critical. Floating point types can introduce rounding errors - it all depends how the value is used. Best solution I've seen in the comments is 1E18M, but really 1E19M may be better ;-)

                                    A 1 Reply Last reply
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                                    • R Rob Grainger

                                      Not sure a cast is the best approach here - decimal types are OK for currency and other situations where accuracy is critical. Floating point types can introduce rounding errors - it all depends how the value is used. Best solution I've seen in the comments is 1E18M, but really 1E19M may be better ;-)

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                                      A Offline
                                      Avi Berger
                                      wrote on last edited by
                                      #33

                                      Yes! I'm sorry I could only give you one five. When the problem domain calls for decimal calculations rather than floating point, casting from a floating point type would be a greater horror.

                                      Please do not read this signature.

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