Python datetime module (original) (raw)

In Python, **date and time are not built-in types but are handled using built-in **datetime module. This module offers classes to efficiently work with dates, times and intervals, providing many useful methods. Date and DateTime are objects, so manipulating them means working with objects, not plain strings or timestamps.

Why do we need Datetime module?

1. Helps work with dates and times in real-world applications like scheduling or logging.
2. Allows easy calculation of differences between two dates or times.
3. Supports formatting and parsing of date/time strings for user-friendly outputs.
4. Useful for time-stamping events, files or data entries.
5. Essential for handling time zones, durations and calendar-based operations.

Commonly used classes in datetime module

Date class

The date class provided by datetime module, is used to create and manipulate date objects. When an instance of this class is created, it represents a specific calendar date in ISO 8601 format: **YYYY-MM-DD.

**Syntax

class datetime.date(year, month, day)

**Parameters:

• **year: An integer between MINYEAR (usually 1) and MAXYEAR (usually 9999).
• **month: An integer from 1 (January) to 12 (December).
• **day: An integer valid for the specified month and year (e.g., 28 or 29 for February, depending on leap year).

**Important Notes

• Providing invalid types (e.g., string instead of int) raises a TypeError.
• Providing out-of-range values raises a ValueError.
• The date object does not include time or timezone information — for that, use datetime.depending on leap year).

**Example 1: Creating a Date Object

Python `

from datetime import date d = date(1996, 12, 11) print(d)

`

**Example 2: Get Current Date

Python `

from datetime import date t = date.today() print(t)

`

**Example 3: Accessing Year, Month and Day Attributes

Python `

from datetime import date t = date.today() print(t.year) print(t.month) print(t.day)

`

**Example 4: Create Date from Timestamp

Python `

from datetime import datetime date_time = datetime.fromtimestamp(1887639468) print(date_time) print(date_time.date())

`

Output

2029-10-25 16:17:48 2029-10-25

**Example 5: Convert Date to String

Python `

from datetime import date t = date.today() date_str = t.isoformat() print(date_str) print(type(date_str))

`

Output

2025-07-26 <class 'str'>

Important Date Class Methods

Time class

The time class in Python represents a specific time of day, independent of any particular date. It is used to create time objects that include hour, minute, second, microsecond and timezone information.

Syntax

class datetime.time(hour=0, minute=0, second=0, microsecond=0, tzinfo=None)

All the arguments are optional. tzinfo can be None otherwise all the attributes must be integer in following range -

• 0 <= hour < 24
• 0 <= minute < 60
• 0 <= second < 60
• 0 <= microsecond < 1000000

**Example 1: Time object representing time in Python

Python `

from datetime import time

Create time object with hour, minute and second

my_time = time(13, 24, 56) print("Entered time:", my_time)

Time object with only minute specified

my_time = time(minute=12) print("Time with one argument:", my_time)

Time object with default (00:00:00)

my_time = time() print("Time without argument:", my_time)

time(hour=26) → ValueError: hour must be in 0..23

time(hour='23') → TypeError: string passed instead of int

`

Output

Entered time: 13:24:56 Time with one argument: 00:12:00 Time without argument: 00:00:00

**Example 2: Get hours, minutes, seconds and microseconds

After creating a time object, its attributes can also be printed separately.

Python `

from datetime import time

Time = time(11, 34, 56) print("hour =", Time.hour) print("minute =", Time.minute) print("second =", Time.second) print("microsecond =", Time.microsecond)

`

Output

hour = 11 minute = 34 second = 56 microsecond = 0

**Example 3: Convert Time object to String

We can convert time object to string using **isoformat() method.

Python `

from datetime import time

Creating Time object

Time = time(12,24,36,1212)

Converting Time object to string

Str = Time.isoformat() print("String Representation:", Str) print(type(Str))

`

Output

String Representation: 12:24:36.001212 <class 'str'>

List of Time class Methods

Datetime class

The datetime class represents both date and time components in a single object. It combines features of the date and time classes, allowing to work with complete timestamps. It uses Gregorian calendar and assumes 24-hour days with exactly 86,400 seconds.

Syntax

class datetime.datetime(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None)

The year, month and day arguments are mandatory. tzinfo can be None, rest all attributes must be an integer in following range -

• MINYEAR <= year <= MAXYEAR
• 1 <= month <= 12
• 1 <= day <= number of days in the given month and year
• 0 <= hour < 24
• 0 <= minute < 60
• 0 <= second < 60
• 0 <= microsecond < 1000000

**Note - Passing an argument other than integer will raise a TypeError and passing arguments outside the range will raise ValueError.

**Example 1: DateTime object representing DateTime in Python

Python `

from datetime import datetime

Initializing constructor

a = datetime(1999, 12, 12) print(a)

Initializing constructor with time parameters as well

a = datetime(1999, 12, 12, 12, 12, 12, 342380) print(a)

`

Output

1999-12-12 00:00:00 1999-12-12 12:12:12.342380

**Example 2: Get year, month, hour, minute and timestamp

After creating a DateTime object, its attributes can also be printed separately.

Python `

from datetime import datetime

a = datetime(1999, 12, 12, 12, 12, 12) print("year =", a.year) print("month =", a.month) print("hour =", a.hour) print("minute =", a.minute) print("timestamp =", a.timestamp())

`

Output

year = 1999 month = 12 hour = 12 minute = 12 timestamp = 945000732.0

**Example 3: Current date and time

You can print current date and time using Datetime.now() function. now() function returns current local date and time.

Python `

from datetime import datetime

Calling now() function

today = datetime.now() print("Current date and time is", today)

`

Output

Current date and time is 2025-07-26 05:24:55.959180

**Example 4: Convert Python Datetime to String

We can convert Datetime to string in Python using datetime.strftime and datetime.isoformat methods.

Python `

from datetime import datetime as dt

Getting current date and time

now = dt.now() string = dt.isoformat(now) print(string) print(type(string))

`

Output

2025-07-26T05:25:45.477917 <class 'str'>

List of Datetime Class Methods

Timedelta Class

Python timedelta class is used for calculating differences in dates and also can be used for date manipulations in Python. It is one of easiest ways to perform date manipulations.

Syntax

class datetime.timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)

All parameters are optional and can be used in any combination

**Example 1: Add days to DateTime object

The timedelta function demonstration

Python `

from datetime import datetime, timedelta

Get the current date and time

now = datetime.now() print("Current Date & Time:", now)

Add 2 years (approx. 730 days)

after_2_years = now + timedelta(days=730) print("After 2 Years:", after_2_years)

Add 2 days

after_2_days = now + timedelta(days=2) print("After 2 Days:", after_2_days)

`

Output

Current Date & Time: 2025-07-26 05:38:58.395824 After 2 Years: 2027-07-26 05:38:58.395824 After 2 Days: 2025-07-28 05:38:58.395824

**Example 2: Difference between two date and times

Date and Time differences can also be found using this class.

Python `

from datetime import datetime, timedelta

Current date and time

now = datetime.now() print("Current Time:", now)

New time after 2 days

new_time = now + timedelta(days=2) print("New Time (+2 days):", new_time)

Time difference

print("Time Difference:", new_time - now)

`

Output

Current Time: 2025-07-26 05:40:17.572931 New Time (+2 days): 2025-07-28 05:40:17.572931 Time Difference: 2 days, 0:00:00

Operations supported by Timedelta Class

Tzinfo class

The tzinfo class in Python is an abstract base for handling time zone info in datetime objects. It can't be used directly instead, subclasses or libraries provide actual time zone support for accurate date-time calculations.

**Note: tzinfo is an abstract base class, so it is not meant to be instantiated directly. Instead, create a subclass of tzinfo and implement its required methods like utcoffset(), dst() and tzname().

**Example:

This example shows how to get system time zone and convert a naive datetime into an aware one using **dateutil.tz.gettz() with "Europe/Berlin" time zone.

Python `

import datetime as dt from dateutil import tz

Get system's local time zone name

tz_string = dt.datetime.now(dt.timezone.utc).astimezone().tzname() print("System Time Zone:", tz_string)

Assigning timezone using dateutil

berlin = tz.gettz('Europe/Berlin') dt1 = dt.datetime(2022, 5, 21, 12, 0) dt2 = dt.datetime(2022, 12, 21, 12, 0, tzinfo=berlin)

print("Naive Object:", dt1.tzname()) print("Aware Object:", dt2.tzname())

`

Output

System Time Zone: UTC Naive Object: None Aware Object: CET

**Explanation:

• **dt.datetime.now(dt.timezone.utc).astimezone().tzname(): gets system’s current time zone name by converting UTC time to local time zone.
• **berlin = tz.gettz('Europe/Berlin'): fetches time zone information for Europe/Berlin.
• **tzname() returns name of time zone for a given datetime object

List of Python DateTime.tzinfo() Objects

Timezone class

Timezones in Python's datetime module help display time for different regions. The pytz module allows easy conversion between timezones, making it useful for apps with international users.

Syntax

timezone(offset, name=None)

**Parameter:

• **offset: A timedelta object (e.g., timedelta(hours=5, minutes=30)).
• **name: Optional string name for the timezone (e.g., "IST").

**Example:

This code shows how to get current UTC time and convert it to different time zones using pytz module. It prints time in UTC, Asia/Kolkata, Europe/Kiev and America/New_York using a consistent format.

Python `

from datetime import datetime from pytz import timezone

format = "%Y-%m-%d %H:%M:%S %Z%z" now_utc = datetime.now(timezone('UTC')) # Current time in UTC print(now_utc.strftime(format))

timezones = ['Asia/Kolkata', 'Europe/Kiev', 'America/New_York'] for tzone in timezones: now_asia = now_utc.astimezone(timezone(tzone)) # Convert to Asia/Kolkata time zone print(now_asia.strftime(format))

`

Output

2025-07-26 06:25:28 UTC+0000 2025-07-26 11:55:28 IST+0530 2025-07-26 09:25:28 EEST+0300 2025-07-26 02:25:28 EDT-0400

**Explanation:

• ****"%Y-%m-%d %H:%M:%S %Z%z":** Defines format for displaying date and time including time zone name (%Z) and UTC offset (%z).
• **datetime.now(timezone('UTC'): Gets current date and time in UTC by attaching UTC time zone to current datetime.
• **now_utc.strftime(format): prints current UTC time formatted according to specified pattern.
• **now_utc.astimezone(timezone(tzone)): converts UTC time to current time zone (tzone).

What is the primary function of the timedelta class in the datetime module?

• To format date and time objects into user-friendly strings.
• To represent a specific point in time (a timestamp).
• To handle time zone information and conversions.
• To represent a duration or the difference between two dates or times.

Explanation:

A timedelta object represents a duration, which can be used to perform date arithmetic, such as adding or subtracting days from a date.

How do you get the current local date and time using the **datetime module?

• datetime.today()
• datetime.now()
• datetime.utcnow()
• date.today()

Explanation:

This method returns a datetime object that represents the current local date and time.

What will be the output of **print(date(2025, 7, 26).weekday()) ?

• 5
• 6
• Saturday
• An error will be raised

Explanation:

This is the correct output, as Saturday is the 6th day of the week when counting starts from Monday at 0.

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