[BangPypers] date/time difference between two dates

[Anand Balachandran Pillai]

On Thu, Feb 19, 2009 at 4:39 PM, Saju Pillai <saju.pillai at gmail.com> wrote:
> LOhit wrote:
>>
>> Hello All,
>>
>> I am parsing a log file to extract data for the last one week from the
>> current date. The log file does not record the year, only month, day of the
>> month and time.
>>
>> My question is, the date is in "Month day-of-the-month time" format in the
>> log file (ex. "Nov 22 15:15:42") and the current date I get from "datetime"
>> module is in ISO format. How do I convert the date in log file to ISO
>> format(or any other format) and then compare with the current date/time.
>
> Look at time.strptime() or datetime.strptime().
>
> This method takes the string to be parsed and the format of the string.
>
> For eg:
>
> time_object = time.strptime("Nov 22 15:15:42", "%b %d %H:%M:%S")
>
> This will give you a time object on which you can call strftime(format,
> time_object) where format is any format you want.
>
> In your particular case, the year will default to 1900, you may want to
> explicitly supply the year like strptime("2008 Nov 22 15:15:42", "%Y %b %d
> %H:%M:%S").

The time,datetime functions in Python have borrowed
a lot in style and semantics from the C language and its
time functions (in time.h) header file.

For example,

>>> import time
>>> time.time()
1235042431.3961599

The "time" function mimics its counterpart "time(...)" in
the C language. The difference being that in Python
it returns both the integer and fractional parts, whereas
in C only the integral time is returned.

Both strftime and strptime are also derived from their
counterparts in C namely "strftime" and "strptime"
respectively and do similar jobs.

"strftime" - literally means format a time structure to
a string with "f" standing for "format".

"strptime" - literally means parse a string representing
time into a time structure with "p" standing for "parse".

Sometimes an understanding of name and semantics
of functions go a long way. Being someone who started
programming with C (and still continues to do), I am
fascinated by how much Python has borrowed from
C, the time/datetime modules being perfect examples.

Not just these functions, but almost the entire time/datetime
functions mimic their C counterparts.

--Anand

>
>
> srp
> --
> http://saju.net.in
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-- 
-Anand