My solution to calculate days between two dates using python

days-between-dates.py

def is_leap_year(year):
    if year % 4 != 0:
        return False
    elif year % 100 != 0:
        return True
    elif year % 400:
        return False
    else:
        return True


def days_between_dates(y1, m1, d1, y2, m2, d2):
    days1 = 0
    days2 = 0
    days_of_months = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

    if is_leap_year(y1):
        days_of_months[1] = 29

    month = 1
    while(month < m1):
        days1 += days_of_months[month]
        month += 1
    days1 += d1

    if not is_leap_year(y2):
        days_of_months[1] = 28

    month = 1
    while(month < m2):
        days2 += days_of_months[month]
        month += 1
    days2 += d2

    days = days2 - days1

    while y1 < y2:
        if is_leap_year(y1):
            days += 366
        else:
            days += 365
        y1 += 1

    return days


print(str(days_between_dates(2012, 2, 1, 2012, 2, 2)) + ' day(s)')
print(str(days_between_dates(2012, 2, 1, 2014, 2, 2)) + ' day(s)')