id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11519	Strange value of ptime variable	a0607892@…	James E. King, III	"The bug is produced by this example program:


{{{
int main() {

    int n = ((20 * 2700 - 4000.0) / 20 / 300.0 + 0.5);
    boost::posix_time::ptime from;
    boost::posix_time::ptime beg = boost::posix_time::time_from_string(""2015-07-29 11:40:00"");
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5);
    beg = beg + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5) + boost::posix_time::minutes(5) +
                boost::posix_time::minutes(5) + boost::posix_time::minutes(5);


    for(int i = 7; i < n; i++) {
        from = beg + boost::posix_time::minutes(5 * i);
        if(from!=beg+ boost::posix_time::minutes(5 * i))
            std::cout << ""ERROR IN TIME: "" << boost::posix_time::to_iso_extended_string(from) << std::endl << boost::posix_time::to_iso_extended_string(beg+ boost::posix_time::minutes(5 * i)) << std::endl;
    }


  return 0;
}
}}}

The result of this code is that it reaches the output (although it shouldn't) and outputs a strange value for ''from''.
I compiled this sample file with g++ 4.6.3 on Ubuntu 12.04 with the compiler flags ''-O3'' and ''-frounding-math''. Although ''-frounding-math'' is necessary to produce this bug for this small example, in a much larger program the bug is still there without this flag.

While debugging this code it seems for me that in
{{{
from = beg + boost::posix_time::minutes(5 * i);
}}}
the minutes are never initialized (but debugging with optimization is quite difficult)."	Bugs	closed	To Be Determined	date_time	Boost 1.58.0	Problem	invalid