Re: bug with -O2 in g++ Debian 4.0.2-9 ?

[Digvijoy Chatterjee <digvijoy_chatterjee at infosys dot com>]

#include<iostream>

using namespace std;
class Rational
{

  int numerator;
  int denominator;
public:
  int GetNum ()
  {
    return numerator;
  }
  int GetDen ()
  {
    return denominator;
  }
  void setNum (int numer)
  {
    numerator = numer;
  }

  void setDen (int den)
  {
    denominator = den;
  }

  int gcd (int i1, int i2) 
  {
    if (i2 == 0)
      return i1;
    else    
      return gcd (i2, i1 % i2);
  }
public :
  Rational (float f)
  {
    int denom = 1;
    while (((int) f  -  f)!= 0) 
      {
        f *= 10;
        denom *= 10;
      }
    int Gcd = gcd (int (f), denom); 
    numerator = f / Gcd;
    cout <<numerator <<endl; 
    denominator = denom / Gcd;
    cout<<"-----"<<endl;
    cout <<denominator <<endl; 
  }
 
};

int
main (int argc, char **argv)
{
  Rational r1 = Rational (.4537f);
}


-----------------------------------------
This runs successfully with:
g++ without any optimization  ,
but with -O or -02 or -03  the executable just hangs forever


On Thu, 2006-02-23 at 10:56 +0100, Jerome Robert wrote:
> Here is the faulty program (this kind of code is generated by
> http://www.swig.org):
> 
> /////////// Start ///////////
> #include <stdio.h>
> 
> int main(void)
> {
>     long long a = 0x77777777L;
>     long long b = 0;
>     void ** aa=(void **)(void *)&a;
>     void ** ab=(void **)(void *)&b;
>     *ab = *aa;
>     printf("in: %llX, out: %llX\n", a, b);
>     return 0;
> }
> /////////// End ///////////
> 
> The output for the following version is:
> (Debian 1:3.3.6-12) g++     in: 77777777, out: 77777777
> (Debian 1:3.3.6-12) g++ -O1 in: 77777777, out: 77777777
> (Debian 1:3.3.6-12) g++ -O2 in: 77777777, out: 77777777
> (Debian 4.0.2-9) g++        in: 77777777, out: 77777777
> (Debian 4.0.2-9) g++ -O1    in: 77777777, out: 77777777
> (Debian 4.0.2-9) g++ -O2    in: 77777777, out: 0
> 
> So there is something wrong with g++ -O2 (Debian 4.0.2-9). Is this program wrong
> or is this a bug ?
> 
> Regards,
> 
> Jerome
-- 
Thanks and Regards
Digvijoy Chatterjee

Please Visit http://indra/LiMS and start your Linux Journey


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