How does python verify date format?

Question

The Python dateutil library is designed for this (and more). It will automatically convert this to a datetime object for you and raise a ValueError if it can't.

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Method #1 : Using strptime()
Method #2 : Using dateutil.parser.parse()
How does Python determine date format?
How do I check if a date is correct in Python?
How does Python validate time?
How does Python implement dates?

As an example:

>>> from dateutil.parser import parse
>>> parse("2003-09-25")
datetime.datetime(2003, 9, 25, 0, 0)

This raises a ValueError if the date is not formatted correctly:

>>> parse("2003-09-251")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jacinda/envs/dod-backend-dev/lib/python2.7/site-packages/dateutil/parser.py", line 720, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "/Users/jacinda/envs/dod-backend-dev/lib/python2.7/site-packages/dateutil/parser.py", line 317, in parse
    ret = default.replace(**repl)
ValueError: day is out of range for month

dateutil is also extremely useful if you start needing to parse other formats in the future, as it can handle most known formats intelligently and allows you to modify your specification: dateutil parsing examples.

It also handles timezones if you need that.

Update based on comments: parse also accepts the keyword argument dayfirst which controls whether the day or month is expected to come first if a date is ambiguous. This defaults to False. E.g.

>>> parse('11/12/2001')
>>> datetime.datetime(2001, 11, 12, 0, 0) # Nov 12
>>> parse('11/12/2001', dayfirst=True)
>>> datetime.datetime(2001, 12, 11, 0, 0) # Dec 11

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Given a date format and a string date, the task is to write a python program to check if the date is valid and matches the format.

Examples:

Input : test_str = ’04-01-1997′, format = “%d-%m-%Y”
Output : True
Explanation : Formats match with date.
Input : test_str = ’04-14-1997′, format = “%d-%m-%Y”
Output : False
Explanation : Month cannot be 14.

Method #1 : Using strptime()

In this, the function, strptime usually used for conversion of string date to datetime object, is used as when it doesn’t match the format or date, raises the ValueError, and hence can be used to compute for validity.

Python3

from datetime import datetime

test_str = '04-01-1997'

print("The original string is : " + str(test_str))

format = "%d-%m-%Y"

res = True

try:

res = bool(datetime.strptime(test_str, format))

except ValueError:

res = False

print("Does date match format? : " + str(res))

Output:

The original string is : 04-01-1997
Does date match format? : True

Method #2 : Using dateutil.parser.parse()

In this, we check for validated format using different inbuilt function, dateutil.parser. This doesn’t need the format to detect for a date.

Python3

from dateutil import parser

test_str = '04-01-1997'

print("The original string is : " + str(test_str))

format = "%d-%m-%Y"

res = True

try:

res = bool(parser.parse(test_str))

except ValueError:

res = False

print("Does date match format? : " + str(res))

Output:

The original string is : 04-01-1997
Does date match format? : True

How does Python determine date format?

“python detect date format” Code Answer's.

>>> import datetime..

>>> def validate(date_text):.

datetime. datetime. strptime(date_text, '%Y-%m-%d').

except ValueError:.

raise ValueError("Incorrect data format, should be YYYY-MM-DD").

How do I check if a date is correct in Python?

Method #1 : Using strptime() In this, the function, strptime usually used for conversion of string date to datetime object, is used as when it doesn't match the format or date, raises the ValueError, and hence can be used to compute for validity.

How does Python validate time?

regex = "([01]?[0-9]|2[0-3]):[0-5][0-9]";.

Where: ( represents the start of the group. [01]?[0-9] represents the time starts with 0-9, 1-9, 00-09, 10-19. ... .

Match the given string with the regex, in Java this can be done by using Pattern. matcher()..

Return true if the string matches with the given regex, else return false..

How does Python implement dates?

Using Strings to Create Python datetime Instances In this code, you use date. fromisoformat() to create a date instance for January 31, 2020. This method is very useful because it's based on the ISO 8601 standard. But what if you have a string that represents a date and time but isn't in the ISO 8601 format?

programming python Convert date Python Python datetime format