Subtracting Dates With Python

Question

I\'m working on a simple program to tell an individual how long they have been alive.

I know how to get the current date, and get their birthday. The only problem is

Answer 1

Create a datetime.datetime from your date:

datetime.datetime.combine(birthdate, datetime.time())

Now you can subtract it from datetime.datetime.now().

>>> from datetime import date, datetime, time
>>> bday = date(1973, 4, 1)
>>> datetime.now() - datetime.combine(bday, time())
datetime.timedelta(14392, 4021, 789383)
>>> print datetime.now() - datetime.combine(bday, time())
14392 days, 1:08:13.593813

Answer 2

import datetime
born = datetime.date(2002, 10, 31)
today = datetime.date.today()
age = today - born

print(age.total_seconds())

Output: 463363200.0

Answer 3

Use UTC time otherwise age in seconds can go backwards during DST transition:

from datetime import datetime

born = datetime(1981, 12, 2) # provide UTC time
age = datetime.utcnow() - born
print(age.total_seconds())

You also can't use local time if your program runs on a computer that is in a different place (timezone) from where a person was born or if the time rules had changed in this place since birthday. It might introduce several hours error.

If you want to take into account leap seconds then the task becomes almost impossible.

Answer 4

from datetime import datetime

birthday = datetime(1988, 2, 19, 12, 0, 0)
diff = datetime.now() - birthday
print diff
# 8954 days, 7:03:45.765329

Answer 5

When substracting two datettime objects you will get a datettime.timedelta object.

from datettime import datetime
x = datetime.now()
y = datetime.now()
delta = y - x

It will give you the time difference with resolution to microsencods.

For more information take a look at the official documentation