Python Time and Date Manipulation Exercises

The datetime module provides classes like datetime, date, and time. To create a specific date and time, you use datetime.datetime(year, month, day, hour, minute, second).

Example:

import datetime

dt = datetime.datetime(2025, 8, 16, 14, 30, 0)
print(dt)  # Output: 2025-08-16 14:30:00

• Option 2 is invalid because datetime must be accessed via the module or imported class.
• Option 3 (date) creates only a date without time.
• Option 4 (time) creates a time object without date.

This is the standard way to work with both date and time in Python for calculations or formatting.

Explanation:
The strptime() method is used to parse a string into a datetime object based on a specified format. It is very useful when reading dates from files, user input, or APIs.

Example:

from datetime import datetime

date_str = "2025-08-16"
dt = datetime.strptime(date_str, "%Y-%m-%d")
print(dt)  # Output: 2025-08-16 00:00:00

• Option 1 (fromtimestamp) expects a Unix timestamp, not a string.
• Options 2 and 3 do not exist in Python’s datetime module.
• Using strptime ensures correct parsing of dates in custom formats, which is essential for reliable date-time manipulation.

The datetime.now() method returns the current local date and time as a datetime object. It is commonly used to timestamp logs, records, or events in applications.

Example:

from datetime import datetime

current_dt = datetime.now()
print(current_dt)  # Output: 2025-08-16 23:45:12.345678

• Option 2 (today) also returns the current date and time but is equivalent to now() without timezone awareness.
• Option 3 (date.today()) returns only the date, without time.
• Option 4 (time.time()) returns a timestamp in seconds since epoch, not a datetime object.

Using datetime.now() is the standard approach when you need both date and time for current operations.

The date() method of a datetime object returns a date object containing only the year, month, and day, omitting the time part. This is useful when you want to compare or display only the date without the time.

Example:

from datetime import datetime

dt = datetime(2025, 8, 16, 14, 30)
only_date = dt.date()
print(only_date)  # Output: 2025-08-16

• Options 1, 2, and 4 are invalid; these methods do not exist.
• Using datetime.date() helps simplify date operations when time is not relevant, such as scheduling or calendar events.

The time class in the datetime module represents time without date. You can create a time object by passing hour, minute, and second.

Example:

from datetime import time

t = time(14, 30, 15)
print(t)  # Output: 14:30:15

• Option 1 is incorrect because datetime.time does not take a year, month, or day.
• Option 3 is invalid; datetime.datetime.time() is a method to extract time from a datetime object, not to create one.
• Option 4 (create_time) does not exist.

Using datetime.time() allows precise time manipulation, like calculating durations or scheduling tasks without involving the date.

To perform date arithmetic, Python uses the timedelta class from the datetime module. Adding a timedelta object to a datetime object updates the date and time accordingly.

Example:

from datetime import datetime, timedelta

dt = datetime(2025, 8, 16)
new_dt = dt + timedelta(days=5)
print(new_dt)  # Output: 2025-08-21 00:00:00

• Option 1 is invalid; datetime.add() does not exist.
• Option 3 (add_days) is not a method in Python.
• Option 4 is partially correct but unnecessarily verbose; timedelta(days=5) is sufficient.

Using timedelta is essential for calculating future or past dates in scheduling, logging, or time-based applications.

The strftime() method converts a datetime object to a formatted string based on format codes. It is widely used to display or store dates in a human-readable or standard format.

Example:

from datetime import datetime

dt = datetime(2025, 8, 16, 14, 30)
formatted = dt.strftime("%d-%m-%Y %H:%M")
print(formatted)  # Output: 16-08-2025 14:30

• Option 1 (to_string) and Option 3 (format) do not exist in the datetime module.
• Option 2 (parse) is used for converting strings to datetime, not formatting.

Using strftime() ensures dates are presented consistently for reports, logs, or UI displays.

The fromtimestamp() method converts a Unix timestamp (number of seconds since January 1, 1970) into a datetime object. This is useful when dealing with timestamps from APIs or logs.

Example:

from datetime import datetime

timestamp = 1692188400
dt = datetime.fromtimestamp(timestamp)
print(dt)  # Output: 2023-08-16 14:00:00 (example)

• Options 1, 2, and 3 do not exist in Python’s datetime module.
• Using fromtimestamp() allows you to work with system timestamps and convert them into human-readable dates.

Subtracting two datetime objects results in a timedelta object. You can then access the .days attribute to get the number of full days between the dates.

Example:

from datetime import datetime

dt1 = datetime(2025, 8, 10)
dt2 = datetime(2025, 8, 16)
diff_days = (dt2 - dt1).days
print(diff_days)  # Output: 6

• Option 1 (seconds) gives the difference in seconds, not days.
• Option 2 (+) is invalid for date difference.
• Option 4 (total_days) does not exist; the correct method is .days.

Using .days is a simple way to calculate durations between events or schedule future tasks in Python.

The weekday() method returns an integer representing the day of the week, where Monday is 0 and Sunday is 6. It is commonly used for scheduling, recurring tasks, or filtering dates.

Example:

from datetime import datetime

dt = datetime(2025, 8, 16)  # Assume this is a Saturday
print(dt.weekday())  # Output: 5

• Option 2 (dayofweek) and Option 3 (get_weekday) do not exist in Python.
• Option 4 (isoweekday) returns 1 for Monday through 7 for Sunday, which is slightly different.

Using weekday() allows consistent handling of weekly schedules in Python applications.

The datetime.utcnow() method returns the current UTC (Coordinated Universal Time) as a datetime object. This is essential for applications that require time standardization across different time zones, such as logging or distributed systems.

Example:

from datetime import datetime

utc_now = datetime.utcnow()
print(utc_now)  # Output: 2025-08-16 17:30:45.123456

• Option 1 (now()) returns the local time, not UTC.
• Options 3 and 4 do not exist in Python.

Using utcnow() ensures that time comparisons are consistent across servers in different regions, which is crucial for APIs and global applications.

The timestamp() method of a datetime object returns the Unix timestamp, representing the number of seconds since January 1, 1970 (UTC). This is often used for storing or exchanging time in databases or APIs.

Example:

from datetime import datetime

dt = datetime(2025, 8, 16, 14, 30)
ts = dt.timestamp()
print(ts)  # Output: 1755486600.0 (example)

• Option 1 (to_seconds) and Option 4 (to_timestamp) do not exist.
• Option 2 (datetime.timestamp(dt)) is not the standard method; timestamp() is called on the object itself.

Using timestamp() is essential for interoperability with systems that rely on Unix time, such as logging, APIs, and scheduling.

To make a naive datetime timezone-aware, you can use the replace(tzinfo=...) method, passing a timezone object from pytz. This associates the datetime with a specific timezone without altering the clock time.

Example:

from datetime import datetime
import pytz

dt = datetime(2025, 8, 16, 14, 30)
tz_aware_dt = dt.replace(tzinfo=pytz.timezone('Asia/Dhaka'))
print(tz_aware_dt)

• Option 2 (pytz.localize(dt)) is another correct method, but in this question we focus on the replace() approach.
• Option 3 (astimezone) requires a timezone-aware datetime initially.
• Option 4 is invalid; datetime.timezone() does not accept a string.

Timezone handling is critical for global applications to ensure consistent scheduling, logging, and comparisons across different regions.

The calendar module provides functions to work with dates at a higher level, including generating text calendars, HTML calendars, and calculating weekdays, leap years, or month ranges. It complements datetime for more structured calendar operations.

Example:

import calendar

# Text calendar for August 2025
text_cal = calendar.month(2025, 8)
print(text_cal)

# Weekday of a specific date (Monday=0)
weekday = calendar.weekday(2025, 8, 16)
print(weekday)  # Output: 5 (Saturday)

• Options 1, 2, and 3 are false; calendar works independently and provides both textual/HTML output and weekday computations.
• Using calendar helps in reporting, scheduling, and date validations without manually computing day-of-week logic.