Formatting and Parsing Dates and Times

Formatting and parsing dates and times is a common task when working with Python. The datetime module provides several functions and classes for formatting and parsing dates and times, as well as performing arithmetic with dates and times.

Datetime Functions

The datetime module provides several functions for formatting dates and times as strings:

• datetime.strftime(): Formats a datetime object as a string using a specified format.
• time.strftime(): Formats a time object as a string using a specified format.
• date.strftime(): Formats a date object as a string using a specified format.

The strftime() function uses format codes to specify the format of the output string.

Strftime() Functions

Some common format codes are:

• %Y: The full year (4 digits)
• %m: The month (2 digits)
• %d: The day of the month (2 digits)
• %H: The hour (2 digits, 24-hour clock)
• %M: The minute (2 digits)
• %S: The second (2 digits)
• %A: The full weekday name
• %B: The full month name
• %I: The hour (2 digits, 12-hour clock)
• %p: The AM/PM indicator

Here is an example of formatting a datetime object as a string:

import datetime

# create a datetime object
dt = datetime.datetime(2022, 12, 24, 12, 34, 56)

# format the datetime object as a string
s = dt.strftime('%Y-%m-%d %H:%M:%S')
print(s)  # Output: 2022-12-24 12:34:56

In this example, the strftime() function formats the datetime object as a string using the specified format.

You can also use the strftime() function to format time and date objects as strings. For example:

import datetime

# create a date object
date = datetime.date(2022, 12, 24)

# format the date object as a string
s = date.strftime('%Y-%m-%d')
print(s)  # Output: 2022-12-24

# create a time object
time = datetime.time(12, 34, 56)

# format the time object as a string
s = time.strftime('%H:%M:%S')
print(s)  # Output: 12:34:56

In these examples, the strftime() function formats the date and time objects as strings using the specified formats.

The datetime module also provides the strptime() function for parsing strings into datetime objects. The strptime() function uses format codes to specify the format of the input string. Here is an example of parsing a string into a datetime object:

import datetime

# parse a string into a datetime object
dt = datetime.datetime.strptime('2022-12-24 12:34:56', '%Y-%m-%d %H:%M:%S')
print(dt)  # Output: 2022-12-24 12:34:56

In this example, the strptime() function parses the string into a datetime object using the specified format.

You can also use the strptime() function to parse strings into date and time objects. For example:

import datetime

# parse a string into a date object
date = datetime.datetime.strptime('2022-12-24', '%Y-%m-%d').date()
print(date)  # Output: 2022-12-24

# parse a string into a time object
time = datetime.datetime.strptime('12:34:56', '%H:%M:%S').time()
print(time)  # Output: 12:34:56

In these examples, the strptime() function parses the strings into date and time objects using the specified formats.

Exercises

To review these concepts, we will go through a series of exercises designed to test your understanding and apply what you have learned.

import datetime

# create a datetime object
dt = datetime.datetime(2022, 12, 24, 12, 34, 56)

# format the datetime object as a string
s = dt.strftime('%Y/%m/%d %H:%M:%S')
print(s)  # Output: 2022/12/24 12:34:56

import datetime

# parse the string into a datetime object
dt = datetime.datetime.strptime('2022/12/24 12:34:56', '%Y/%m/%d %H:%M:%S')
print(dt)  # Output: 2022-12-24 12:34:56

import datetime

# create a datetime object for the current date and time
dt = datetime.datetime.now()

# format the datetime object as a string
s = dt.strftime('%m/%d/%Y')
print(s)  # Output: 01/20/2022 (or similar)

import datetime

# parse the string into a datetime object
dt = datetime.datetime.strptime('January 20, 2022', '%B %d, %Y')
print(dt)  # Output: 2022-01-20 00:00:00

import datetime

# create a datetime object for the current date and time
dt = datetime.datetime.now()

# create a timedelta object for 1 day and 2 hours
td = datetime.timedelta(days=1, hours=2)

# add the timedelta object to the datetime object
dt2 = dt + td
print(dt2)  # Output: 2022-01-21 14:34:56.789012 (or similar)