7.8. Datetime Timestamp
7.8.1. What is timestamp?
Seconds since midnight of January 1st, 1970 (1970-01-01 00:00:00 UTC)
Unix era, also known as "epoch"
In most systems represented as 32-bit integer
Max value is 2,147,483,647 (2038-01-19 03:14:07 UTC)
Min value is -2,147,483,647 (1901-12-13 20:45:52 UTC)
If you add 1 to max value, you will get overflow to min value
Linux kernel 5.6 (released 29 March 2020) has a fix for this problem so that 32-bit systems can run beyond the year 2038
https://lore.kernel.org/lkml/CAHk-=wi9ZT7Stg-uSpX0UWQzam6OP9Jzz6Xu1CkYu1cicpD5OA@mail.gmail.com/
Excel error: https://learn.microsoft.com/en-US/office/troubleshoot/excel/wrongly-assumes-1900-is-leap-year
7.8.2. Get current timestamp
Get current timestamp using datetime module:
>>> from datetime import datetime
>>>
>>>
>>> current_timestamp = datetime.now().timestamp()
Get current timestamp using time module:
>>> import time
>>>
>>>
>>> current_timestamp = time.time()
7.8.3. Convert timestamp to datetime
Convert timestamp to datetime:
>>> from datetime import datetime
>>>
>>>
>>> datetime.fromtimestamp(267809220)
datetime.datetime(1978, 6, 27, 17, 27)
JavaScript has timestamp in milliseconds
To convert from milliseconds we have to divide by 1000
Convert JavaScript timestamp to datetime:
>>> from datetime import datetime
>>>
>>> MILLISECONDS = 1000
>>>
>>> datetime.fromtimestamp(267809220000 / MILLISECONDS)
datetime.datetime(1978, 6, 27, 17, 27)
7.8.4. Assignments
# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author
# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`
# %% About
# - Name: Datetime Timestamp Limits
# - Difficulty: easy
# - Lines: 1
# - Minutes: 5
# %% English
# 1. Convert given dates to `datetime` objects
# 2. Print timestamp for each date
# 3. What is special about those dates?
# 4. Run doctests - all must succeed
# %% Polish
# 1. Przekonwertuj podane daty do obiektów `datetime`
# 2. Wypisz timestamp każdej daty
# 3. Co to za daty?
# 4. Uruchom doctesty - wszystkie muszą się powieść
# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> assert type(a) is float, \
'`a` must be a float object'
>>> assert type(b) is float, \
'`b` must be a float object'
>>> assert type(c) is float, \
'`c` must be a float object'
>>> a
-2115947647.0
>>> b
0.0
>>> c
2147483647.0
"""
from datetime import datetime
A = '1902-12-13T20:45:53+00:00'
B = '1970-01-01T00:00:00+00:00'
C = '2038-01-19T03:14:07+00:00'
# timestamp of A
# type: float
a = ...
# timestamp of B
# type: float
b = ...
# timestamp of C
# type: float
c = ...