calculate the days between two dates

Question

I did a program that calculates the days different, between two dates, but I am not sure how can I add a statement that makes sure the program wont include the end date.

Answer 1

You can check if argv[7] is "include" using strcmp from <string.h>, and set a variable to ignore the end date if it's not

    /* Rest of the code above */

    if (mm2<mm1) {
        mm2 += 12;
        yyyy2 -= 1;
    }

    int include = 0;
    if (argc >= 8)
    {
        if (strcmp("include", argv[7]) == 0)
        {   
            include = 1;
        }
    }

    day_diff = dd2 - dd1;
    if (include == 0)
    {
        day_diff--;
    }
    printf("%d", day_diff);

    return 0;

But i recommend you search about getopts, a flag seems more user friendly
./daysCalculatorA -i 19 2 2019 22 4 2019

Answer 2

my code is calculating month and days but only printing days, its 86 days or 2 months and 25 days! how do i edit that so it shows 86?

This is a typical case of "Don't (try to) reinvent the wheel." Use the Standard C mktime function to convert broken-down times into time values which can be subtracted from each other.

#include <time.h>
…
  time_t t1, t2;
  t1 = mktime(&(struct tm){ .tm_mday=dd1, .tm_mon=mm1-1, .tm_year=yyyy1-1900 });
  t2 = mktime(&(struct tm){ .tm_mday=dd2, .tm_mon=mm2-1, .tm_year=yyyy2-1900 });
  day_diff = (t2 - t1) / 24 / 60 / 60 + include;    // make days from seconds