Calculate days until your next birthday in python

Question

In the code above I wanted to calculate days until next birthday but the output is wrong. what it should be: My birth day: Feb 20 2002 => 203 days until my birthday(today is july 31 2018) what it actually is: input: Feb 20 2002 => 179 days

My code:

import datetime


def get_user_birthday():
    year = int(input('When is your birthday? [YY] '))
    month = int(input('When is your birthday? [MM] '))
    day = int(input('When is your birthday? [DD] '))

    birthday = datetime.datetime(year,month,day)
    return birthday


def calculate_dates(original_date, now):
    date1 = now
    date2 = datetime.datetime(now.year, original_date.month, original_date.day)
    delta = date2 - date1
    days = delta.total_seconds() / 60 /60 /24

    return days


def show_info(self):
    pass



bd = get_user_birthday()
now = datetime.datetime.now()
c = calculate_dates(bd,now)
print(c)

Answer 1

A couple of problems:

1. Year must be specified as a complete integer, i.e. 2002, not 02 (or 2).
2. You need to check whether or not your birthdate has passed for this year.

Below is a solution which corrects these 2 issues. Given your input 20-Feb-2002 and today's date 31-Jul-2018, your next birthday is in 203 days' time.

In addition, note you can use the days attribute of a timedelta object, which will round down to 203 days and avoid the decimal precision.

from datetime import datetime

def get_user_birthday():
    year = int(input('When is your birthday? [YY] '))
    month = int(input('When is your birthday? [MM] '))
    day = int(input('When is your birthday? [DD] '))

    birthday = datetime(2000+year,month,day)
    return birthday

def calculate_dates(original_date, now):
    delta1 = datetime(now.year, original_date.month, original_date.day)
    delta2 = datetime(now.year+1, original_date.month, original_date.day)
    
    return ((delta1 if delta1 > now else delta2) - now).days

bd = get_user_birthday()
now = datetime.now()
c = calculate_dates(bd, now)

print(c)

When is your birthday? [YY] 02
When is your birthday? [MM] 02
When is your birthday? [DD] 20

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