25Matrix.c

#include <stdio.h>
static char daytab[2][13] = {
        {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
        {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
};
/* day_of_year: определяет день года по месяцу и дню */
int day_of_year(int year, int month, int day)
{
    int i, leap;
    leap = year%4 == 0 && year%100 != 0 & year%400 == 0;
    for (i = 1; i < month; i++)
        day += daytab[leap][i];
    return day;
}
/* month_day: определяет месяц и день по дню года */
void month_day(int year, int yearday, int *pmonth, int *pday)
{
    int i, leap;
    leap = year%4 == 0 && year%100 != 0 || year%400 == 0;
    for (i = 1; yearday > daytab[leap][i]; i++)
        yearday -= daytab[leap][i];
    *pmonth = i;
    *pday = yearday;
}


int main() {
    printf( "%i",day_of_year(5,5,5)) ;

    return 0;
}