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Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question: ⭐ (dates and times)

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?

Originally posted as a Categorized Question.

Replies are listed 'Best First'.
Re: Fast(er) date parsing⭐
by spoon! (Initiate) on Nov 07, 2005 at 05:07 UTC
    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';

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Re: Fast(er) date parsing
by lhoward (Vicar) on Jul 19, 2000 at 01:29 UTC
    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.
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Re: Fast(er) date parsing
by fundflow (Chaplain) on Jul 20, 2000 at 02:08 UTC
    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);

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    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.

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[d/l]
      If you just want to check if the event was in the last 24 hours without using any module, you could compare 
      my @yesterday=localtime time-24*60*60;
if( (sprintf"%02d"x6, $yesterday[5]+1900,@yesterday[4,3,2,1,0])
  < (sprintf"%02d"x6, $year,$months{$month},$mday,$hour,$min,$sec)
)

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Re: Fast(er) date parsing
by crazyinsomniac (Prior) on Jul 19, 2000 at 03:01 UTC 
    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);

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[d/l]
      Sorry about that
       my $day;
 my $month;
 my $date;
 my $time;
  my $hour;
  my $min;
  my $sec;
 my $year;

 ($day,$month,$date,$time,$year)=split(" ","Mon Jul 17 17:59:31 2000")
+;
 ($hour,$min,$sec)=split(":",$time);

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       ______________________________________________
|_____¸.·ooO--(> cRaZy is co01. <)--Ooo·.¸_____|
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[d/l]
        my ($day,$month,$date,$hour,$min,$sec,$year)=split /[ :]/,"Mon Jul 17 
+17:59:31 2000";

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        cLive ;-)
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Re: Fast(er) date parsing
by chanio (Priest) on Nov 08, 2005 at 14:53 UTC
    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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