Thread: date-time related problem

Hi all,

I'm writing a function which extracts the day, month and year value from a pre-defined timestamp format passed by the caller. This format is: NDDD
where N is the decade number after 2000 and DDD is the day of the year. so if the timestamp is: 1001. the year would be: 2001, month would be: January and day would 1 (corresponding to 1 Jan 2001).

I've written this code for this:

Code:

int main( int argc, char **argv )
{
   long       julian_day_num   = 1001;
   int        year_val         = 0;
   int        decade_indicator = 0;
   time_t     time_epoch       = 0;

   struct tm  tm_stru;

   memset( &tm_stru, 0, sizeof( tm_stru ) );
   errno = 0;

   decade_indicator = ( julian_day_num / 1000 );
   year_val = 2000 + decade_indicator;

   tm_stru.tm_year = year_val - 1900;
   tm_stru.tm_yday = julian_day_num - ( decade_indicator * 1000 );
   printf( "initial tm_yday  is : %d\n", tm_stru.tm_yday );

   time_epoch = mktime( &tm_stru );

   printf( "year_val is         : %d\n", year_val );
   printf( "decade_indicator is : %d\n", decade_indicator );
   printf( "tm_stru values after mktime() ....\n" );
   printf( "tm_yday    : %d\n", tm_stru.tm_yday );
   printf( "tm_year    : %d\n", tm_stru.tm_year );
   printf( "tm_mon     : %d\n", tm_stru.tm_mon  );
   printf( "tm_day     : %d\n", tm_stru.tm_mday );

   printf( "errno is: %d\n", errno );


   return 0;

} /* end of main() */

But this is giving me this result:

Code:

initial tm_yday  is : 1
year_val is         : 2001
decade_indicator is : 1
tm_stru values after mktime() ....
tm_yday    : 365
tm_year    : 100
tm_mon     : 11
tm_day     : 31              
errno is: 0

Which is not what I was expecting. What am I missing here???

Any help would be appreciated. Thanks.

This format is: NDDD
where N is the decade number after 2000 and DDD is the day of the year. so if the timestamp is: 1001. the year would be: 2001, month would be: January and day would 1 (corresponding to 1 Jan 2001).

Um... no it's not. According to the above description, where N is the decade, the year should be: 2010.

Decade = 10 years.
N = 1, thus the year would be 2010.

According to the formulae, DDD is not enough to hold the potential for 10 years worth of days. You need to correct your formulae:

NNDDD

or

NDDDD

Quzah.