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Fast(er) date parsing

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Contributed by Anonymous Monk on Jul 19, 2000 at 01:19 UTC
Q&A  > dates and times


Description:

I need to parse dates that are in the standard format:

    Mon Jul 17 17:59:31 2000

Currently i'm using Date::Parse but this is fairly slow.
Does anyone have a specialized and possibly faster way to do it?
Maybe a combination of split() with table lookup?

Answer: Fast(er) date parsing
contributed by spoon!

I think the POSIX::strptime module is what you're looking for. It has an strptime() function that acts as the inverse of strftime():

use POSIX::strptime; use Time::Local; my $result = timelocal strptime $d, '%a %b %e %H:%M:%S %Y';
Answer: Fast(er) date parsing
contributed by lhoward

Since you know the format and the format is constant then the fastest parser would probably be a split, followed by a month name to month number lookup table. Then take all your numbers and add throw them into an apropriate equation to get the timestamp format and voila.

Answer: Fast(er) date parsing
contributed by fundflow

Thanks guys, maybe i wasn't clear. I want to get the unix timing (since epoch) from the data and was wondering if there is an inverse function to strftime(). I just realized that its not that hard and so here is my solution, following lhoward's suggestion:

use Time::Local; my %months = ( Jan=> 0, Feb=> 1, Mar=> 2, Apr=> 3, May=>4, Jun=> 5, Jul=> 6, Aug=> 7, Sep=> 8, Sep=> 8, Oct=> 9, Nov=> 10, Dec= +> 11); # Parse the date: Fri Jun 30 11:07:39 2000 my ($day, $month, $mday, $time, $year)=split(" ", $d); my ($hour,$min,$sec)=split(":",$time); my $result = timelocal($sec,$min,$hour,$mday,$months{$month},$year);

I'd prefer not having to use any module but this seems reasonable
The reason i need this is to go through some log files and print a summary of the events that happened in the past 24 hours.

Answer: Fast(er) date parsing
contributed by crazyinsomniac

my( $day, $month, $date, $time, $hour, $min, $sec, $year); ($day,$month,$date,$time,$year)=split(" ","Mon Jul 17 17:59:31 2000"); ($hour,$min,$sec)=split(":",$time);
Answer: Fast(er) date parsing
contributed by chanio

See the great Date::Calc that has plenty of functions to do this:

perl -MDate::Calc -e'my $string="8 nov,2005";my ($year,$month,$day)= D +ate::Calc::Decode_Date_EU($string); print("\n$year/$month/$day\n")' 2005/11/8

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