Exercise 5.8. There is no error checking in day_of_year or month_day. Remedy this defect.

Exercise 5.8. There is no error checking in day_of_year or month_day. Remedy this defect.

/* day_of_year */

int day_of_year(int year, int month, int day)

{

    int i, leap;

    

    if(year < 1)

        return -1;

    leap = (year%4 == 0 && year%100 != 0) || year%400 == 0;

    if(month < 1 || month > 12)

        return -1;

    if(day < 1 || day > daytab[leap][month])

        return -1;

    for(i = 1; i < month; i++)

        day += daytab[leap][i];

    return day;

}

/* month_day */

void month_day(int year, int yearday, int *pmonth, int *pday)

{

    int i, leap;

    

    if(year < 1 || yearday < 1)

    {

        *pmonth = -1;

        *pday = -1;

        return;

    }

    leap = (year%4 == 0 && year%100 != 0) || year%400 ==  0;

    if(leap == 1 && yearday > 366)

    {

        *pmonth = -1;

        *pday = -1;

        return;

    }

    if(leap == 0 && yearday > 365)

    {

        *pmonth = -1;

        *pday = -1;

        return;

    }        

    for(i = 0; yearday > daytab[leap][i]; i++)

        yearday -= daytab[leap][i];

    *pmonth = i;

    *pday = yearday;

}