Go4Expert - Is it a Bug in g++ compiler`s -O flag??

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Is it a Bug in g++ compiler`s -O flag??

The output is different for the following two codes when compiled as : "g++ -O foo.cpp"
1st COde :

Code:

#include<iostream.h>

#include<math.h>

int main(){

        double d=log(8)/log(2);

        cout<<"d="<<d<<"\t floor(d)="<<floor(d);        //<<"\t"<<floor(10.0)<<"\n";

        return 0;

}

------------------------------------------------------------------------------------------------------------------
2nd COde :

Code:

#include<iostream.h>

#include<math.h>

int main(){

        double d=log(8)/log(2);

        cout<<"d="<<d<<"\t floor(d)="<<floor(d)<<"\t"<<floor(10.0)<<"\n";

        return 0;

}

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Expected output : d=3 floor(d)=3 10
But The First code give : d=3 floor(d)=2 10
while the second gives the right output.
Could nyone plz explain whats going wrong!!

Nikhil

Re: Is it a Bug in g++ compiler`s -O flag??

Quote:

Originally Posted by nikhil_dokania

Expected output : d=3 floor(d)=3 10

Nope. Its should be d=3 floor(d)=2 10 because log(8)/log(2) = 2.999999..... and so floor should be 2.

I guess the difference in output should be a bug as far as I think.

Re: Is it a Bug in g++ compiler`s -O flag??

i think u r right. and thanx for replying. But the difference in output is not recognized as a Compiler bug. I jus learned it from this GCC website. Check it out: http://gcc.gnu.org/bugs.html#nonbugs_general