🔷 Introduction

Handling dates and time is essential in many real-world applications such as scheduling systems, logs, data analysis, and APIs.

Python provides a powerful built-in module called datetime to work with dates and time efficiently.

In this lesson, you will learn:

✔ How to create and manipulate dates
✔ How to format and parse date strings
✔ How to perform time calculations
✔ How to work with durations using timedelta

🟩 1. The `datetime` Module

🔹 Importing

from datetime import datetime

🔹 Get current date and time

now = datetime.now()
print(now)

🔹 Get only the date

print(now.date())

🔹 Get only the time

print(now.time())

🟩 2. Creating Custom Dates

from datetime import datetime

d = datetime(2025, 1, 15, 10, 30)
print(d)

✔ Format: datetime(year, month, day, hour, minute)

🟩 3. Formatting Dates (`strftime`)

Convert date → string:

now = datetime.now()

print(now.strftime("%Y-%m-%d"))
print(now.strftime("%d/%m/%Y"))
print(now.strftime("%H:%M:%S"))

🔹 Common format codes

Code	Meaning
%Y	Year
%m	Month
%d	Day
%H	Hour
%M	Minute
%S	Second

🟩 4. Parsing Dates (`strptime`)

Convert string → date:

from datetime import datetime

date_str = "2025-01-15"
date_obj = datetime.strptime(date_str, "%Y-%m-%d")

print(date_obj)

🟩 5. Time Calculations (`timedelta`)

🔹 Adding time

from datetime import timedelta

now = datetime.now()
future = now + timedelta(days=7)

print(future)

🔹 Subtracting dates

past = datetime(2024, 1, 1)
diff = now - past

print(diff.days)

🟩 6. Practical Examples

🔹 Calculate age

birth = datetime(2000, 5, 10)
today = datetime.now()

age = today.year - birth.year
print("Age:", age)

🔹 Check if a date is in the future

event = datetime(2025, 12, 31)

if event > datetime.now():
    print("Event is upcoming")

🟧 7. Exercises (Hidden Solutions)

Exercise 1 — Print current date

from datetime import datetime
print(datetime.now())

Exercise 2 — Format today’s date

from datetime import datetime
print(datetime.now().strftime("%d/%m/%Y"))

Exercise 3 — Parse a date string

from datetime import datetime
d = datetime.strptime("2025-05-10", "%Y-%m-%d")
print(d)

Exercise 4 — Add 10 days to today

from datetime import datetime, timedelta
print(datetime.now() + timedelta(days=10))

Exercise 5 — Calculate difference between two dates

from datetime import datetime
d1 = datetime(2025, 1, 1)
d2 = datetime(2024, 1, 1)

print((d1 - d2).days)

🟦 Conclusion

In this lesson, you learned how to:

✔ Work with dates and time using datetime
✔ Format and parse date strings
✔ Perform time calculations
✔ Handle real-world date scenarios

These skills are widely used in:

APIs
Data analysis
Logging systems
Scheduling applications

🚀 Mini Project — Event Scheduler & Countdown App

Project idea

Build a Python program that lets the user:

enter an event name
enter an event date
calculate how many days remain until the event
show whether the event is in the future, today, or already passed

This project is perfect for practicing:

datetime
strptime()
strftime()
date comparison
timedelta

🧩 What the app does

Example:

Enter event name: Python Exam
Enter event date (YYYY-MM-DD): 2026-12-20

Output:

Event: Python Exam
Date: 20/12/2026
Days remaining: 45

If the date is today:

The event is today!

If the date is in the past:

This event has already passed.

✅ Full Solution

from datetime import datetime

event_name = input("Enter event name: ")
event_date_str = input("Enter event date (YYYY-MM-DD): ")

try:
    event_date = datetime.strptime(event_date_str, "%Y-%m-%d").date()
    today = datetime.now().date()

    difference = event_date - today
    days_left = difference.days

    print("\nEvent:", event_name)
    print("Date:", event_date.strftime("%d/%m/%Y"))

    if days_left > 0:
        print("Days remaining:", days_left)
    elif days_left == 0:
        print("The event is today!")
    else:
        print("This event has already passed.")

except ValueError:
    print("Invalid date format. Please use YYYY-MM-DD.")

🔍 Explanation

1. Read user input

event_name = input("Enter event name: ")
event_date_str = input("Enter event date (YYYY-MM-DD): ")

The user enters:

the event title
the date as text

2. Convert string to date

event_date = datetime.strptime(event_date_str, "%Y-%m-%d").date()

This transforms "2026-12-20" into a real Python date object.

3. Get today's date

today = datetime.now().date()

4. Calculate difference

difference = event_date - today
days_left = difference.days

This gives the number of days between today and the event.

5. Display the result

If days_left > 0 → upcoming event
If days_left == 0 → event is today
If days_left < 0 → event already passed

🧠 Skills practiced

With this mini project, you practice:

parsing dates with strptime()
formatting dates with strftime()
comparing dates
using timedelta indirectly through date subtraction
handling invalid input with try/except

🛠 Improved Version — Multiple Events

Here is a slightly more advanced version that stores several events in a list.

from datetime import datetime

events = []

while True:
    name = input("\nEnter event name (or type 'stop' to finish): ")
    if name.lower() == "stop":
        break

    date_str = input("Enter event date (YYYY-MM-DD): ")

    try:
        event_date = datetime.strptime(date_str, "%Y-%m-%d").date()
        events.append((name, event_date))
    except ValueError:
        print("Invalid date format. Please use YYYY-MM-DD.")

today = datetime.now().date()

print("\n=== Event Schedule ===")
for name, event_date in events:
    days_left = (event_date - today).days
    print(f"\nEvent: {name}")
    print("Date:", event_date.strftime("%d/%m/%Y"))

    if days_left > 0:
        print("Days remaining:", days_left)
    elif days_left == 0:
        print("The event is today!")
    else:
        print("This event has already passed.")

🎯 Challenge ideas

You can extend the project with:

sort events by nearest date
save events to a file
show only future events
add event time
create a GUI version with Tkinter
highlight the nearest upcoming event