📘 Lesson 25 · Advanced

Python Datetime

Work with dates and times using datetime, strftime, strptime, and timedelta.

The datetime Module

Python's datetime module provides classes for working with dates and times. The main ones: datetime (date + time combined), date (date only), time (time only), and timedelta (a duration). They are all in the standard library — no installation needed.

Getting the Current Date and Time

now.py

from datetime import datetime, date

now = datetime.now()
print(now)
print(f"Year: {now.year}, Month: {now.month}, Day: {now.day}")
print(f"Time: {now.hour}:{now.minute:02d}:{now.second:02d}")
print(date.today())

▶ Output

2024-01-15 14:32:07.123456
Year: 2024, Month: 1, Day: 15
Time: 14:32:07
2024-01-15

Formatting with strftime()

strftime() converts a datetime to a formatted string. The format codes start with %: %Y = 4-digit year, %m = month number, %d = day, %B = full month name, %A = weekday name, %H = hour (24h), %I = hour (12h), %p = AM/PM.

strftime.py

from datetime import datetime
now = datetime.now()
print(now.strftime("%d/%m/%Y"))
print(now.strftime("%B %d, %Y"))
print(now.strftime("%I:%M %p"))
print(now.strftime("%A, %d %B %Y"))

▶ Output

15/01/2024
January 15, 2024
02:32 PM
Monday, 15 January 2024

Parsing with strptime()

strptime() parses a date string into a datetime object. You must supply the exact format that matches the string. Essential when reading dates from user input or files.

strptime.py

from datetime import datetime
dt = datetime.strptime("25/12/2024", "%d/%m/%Y")
print(dt)
print(dt.strftime("%A"))  # what day of the week?

▶ Output

2024-12-25 00:00:00
Wednesday

Date Arithmetic with timedelta

A timedelta represents a duration. Add or subtract from dates to get future or past dates — useful for deadlines, expiry times, and scheduling.

timedelta.py

from datetime import datetime, timedelta
now = datetime.now()
print((now + timedelta(days=30)).strftime("%d %b %Y"))
print((now - timedelta(weeks=2)).strftime("%d %b %Y"))

d1 = datetime(2024, 1, 1)
d2 = datetime(2024, 12, 31)
print(f"Days in 2024: {(d2-d1).days}")

▶ Output

14 Feb 2024
01 Jan 2024
Days in 2024: 365

✅

For timezone-aware datetimes, use zoneinfo (Python 3.9+) or the third-party pytz library. Naive datetime objects can cause subtle bugs in production.

🧠 Quick Check

Which method formats a datetime as a string?

strptime()

format()

strftime()

tostring()