Hi Frederic,

You asked:

FT> How do you calculate the day of the year in C?

Lots of ways...
There is one in SNIPPETS, but I consider the method used cumbersome and
slower than needed.

Code sample:

/* 21/12/98 G. White                   */
/* Use freely, no responsibility taken */

/* Prototype */
int  day_no (int year,int month,int day);

/* Assumes valid calendar dates:-  */
/* year = full calendar year       */
/* month: 1 to 12                  */
/* day: 1 to 31                    */
/* So for the writing date:- year = 1998; month = 12; day = 21;   */
/* If months are zero based remove the first element of days[]    */
/* If days are zero based increase the return value by one        */

const int days[] = {0,0,31,59,90,120,151,181,212,243,273,304,334};

int day_no (int year,int month,int day)
{
if ((month > 2) && ((((year % 4) == 0) && ((year % 100) != 0)) ||
          ((year % 400) == 0)))
  return days[month] + day + 1;
else
  return days[month] + day;
}

/* End sample */

There are plenty of other ways of organising even something this simple,
especially the leap year checking line...

Untested, typed straight into the message. (Get out just in case ).

George

 * SLMR 2.1a * Wishing you a Happy Christmas and a Peaceful New Year

--- Maximus/2 3.01