Thread: function days from date to december 31st

Code:

#include <stdio.h>
#include <time.h>
int days, month, year, days_1, month_1, year_1, leapy, ndays, ddays, days_total, days_beforeleap;

int daysinmonth(int month) /*there is a problem in this statement, your printf is reading out ridiculous numbers for days, don't forget to ask*/
{
        switch(month)
        {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
                return 31;
        case 2:
                return 28;
        case 4:
        case 6:
        case 9:
        case 11:
                return 30;
        default:
                return -1;
        }
}
int leap(int year)
{
        if(year%400 ==0 || (year%100 != 0 && year%4 == 0))
        {
        leapy=1;
        }
        else
        {
        leapy=0;
        }

}
int daystoyear(month, month_1, year, year_1)
{
int i=0, days_toend, years_todays;
days_toend=daysinmonth(month)-days;
        while(month<month_1)
        {
        daysinmonth(month);
        month++;
        }
years_todays=365*(year_1-year);
days_beforeleap=days_toend+years_todays;
return days_beforeleap;
}
daysinyear(int days, int month, int days_1, int month_1)
{
int i=0;
days_total = daysinmonth(month) - days;

for(i = month+1;i < month_1 - 1;++i);
days_total += daysinmonth(i);
days_total += days_1;
return days_total;
}

int main(void)
{
int days_1, month_1, year_1;
char a, b, a1, b1;
printf("intput a date in the follwing format:\n");
printf("mmddyyyy: in other words the two digit day,two digit month,\n");
printf("and four digit year, with no slashes or heifens anywhere.\n");
scanf("%d%c%d%c%d", &month, &a, &days, &b, &year);
        if(month<0 || month>12 || days<0 || days>31 || year<0)
        {
        printf("data not valid");
        }
printf("enter the later date in the same format:\n");

scanf("%d%c%d%c%d", &month_1, &a1, &days_1, &b1, &year_1);
daystoyear(month, month_1, year, year_1);
printf("total days=%d",days_beforeleap);
}

the function days in year is supposed to read the number of days from a date to the end of the year. I don't think the while loop is working but I don't know why. Is it a recursive function problem?

Code:

for(i = month+1;i < month_1 - 1;++i); /* <<-- here is your newbie mistake */
days_total += daysinmonth(i);
days_total += days_1;
return days_total;
}

I think that for loop is what causes my date totals to be 60 and 61 for 1/1/1 to 1/1/1 and 1/1/1 to 1/1/2. I've toyed with it a bit, but I can't seem to find the exact logic problem.

Am I overthinking it? would this work?

Code:

for(i=month;i<month_1;++i);

Delete line 60 and see what happens...

AHA! the semicolon! Thanks, and hello again tater, always a pleasure!

ok, it now works for dates in the same month(and year of course), but the values come up about two months short for long amounts of time. For example, 1/1/1 to 12/31/1 comes out to 305 days. Here's the new function:

Code:

daysinyear(int days, int month, int days_1, int month_1)
{
int i;
for(i = month+1;i < month_1 - 1;++i)
days_total += daysinmonth(i);
days_total+=days_1;
days_total=days_total-1;
return days_total;
}

Oh, and I added line 7 because the values in the same month were 1 day off, but I'm not sure how wise that was now...