datetime.strftime() / datetime.strptime()

from datetime import datetime

# Converts a datetime object to a formatted string.
string = datetime_object.strftime(format_string)

# Creates a datetime object from a formatted string.
dt = datetime.strptime(string, format_string)

from datetime import datetime

# Display the current datetime in various formats.
now = datetime.now()

# Slash-separated format
print(now.strftime('%Y/%m/%d %H:%M:%S'))
# Example output: '2025/04/15 14:30:00'

# ISO 8601 format
print(now.strftime('%Y-%m-%dT%H:%M:%S'))
# Example output: '2025-04-15T14:30:00'

# Date only (slash-separated)
print(now.strftime('%Y/%m/%d'))
# Example output: '2025/04/15'

# 12-hour format with weekday
print(now.strftime('%Y/%m/%d (%A) %I:%M %p'))
# Example output: '2025/04/15 (Tuesday) 02:30 PM'

# Use strptime() to create a datetime object from a string.
date_str = '2025-04-15 09:30:00'
dt = datetime.strptime(date_str, '%Y-%m-%d %H:%M:%S')
print(dt)          # Outputs: '2025-04-15 09:30:00'
print(type(dt))    # Outputs: '<class 'datetime.datetime'>'

# Parse a date string in slash-separated format.
date_str2 = '2025/4/15'
dt2 = datetime.strptime(date_str2, '%Y/%m/%d')
print(dt2.year)   # Outputs: '2025'
print(dt2.month)  # Outputs: '4'

# Convert a date received from a web form.
form_input = '15/04/2025'
dt3 = datetime.strptime(form_input, '%d/%m/%Y')
formatted = dt3.strftime('%Y-%m-%d')
print(formatted)  # Outputs: '2025-04-15'

'strftime()' stands for "string format time" and converts a datetime object to a string in any format you specify. 'strptime()' stands for "string parse time" and creates a datetime object from a formatted string. Both functions use the same format codes, so learning them once lets you use both.

The behavior of some format codes may vary slightly by operating system. For example, the code for removing leading zeros from month or day values ('%-m' on Linux) does not work on Windows. If you need to strip leading zeros, it is more portable to convert the string first and then remove them with 'lstrip("0")'.

For creating datetime objects, see 'datetime.datetime() / datetime.date() / datetime.time()'.