abhishes has asked for the wisdom of the Perl Monks concerning the following question:

Hello Perl Monks!

I am parsing a file where I find strings of the following pattern 2003/02/05 17:32:06.179

I am able to extract the year, month, day, hour, minute, second and millisecond from this string using a regular expression.

But if I have two such strings how to find out which of the two is smaller. Is there a speedy way to compare two such strings for time.

Thanks for your help in advance.

regards,
Abhishek.

Replies are listed 'Best First'.
Re: How to compare time in perl
by mojotoad (Monsignor) on Feb 08, 2003 at 18:39 UTC
    You don't have to parse the dates. Since the strings are a) constant width and consistently formatted, and b) organized left-to-right in order of granularity, you can simply use a string comparison. Like so: 

    #!/usr/bin/perl

@data = <DATA>;
chomp @data;

foreach (sort { $a cmp $b } @data) {
  print "$_\n";
}


__END__
2003/02/05 17:32:06.179
2003/02/05 17:32:06.159
2003/01/05 17:32:06.179
1999/01/05 17:32:06.179

    [download]
    When run this prints:
    1999/01/05 17:32:06.179
2003/01/05 17:32:06.179
2003/02/05 17:32:06.159
2003/02/05 17:32:06.179

    [download]

    Matt

[reply]
[d/l]
[select]

      The equal width and 0 packing of single digits is vital as this will choke cmp: 

      2003/02/05 2:32:06.179
2003/02/05 17:32:06.179
2003/02/05 20:32:06.159

      [download]
      cheers

      tachyon

      s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

[reply]
[d/l]
        Even if they aren't to begin with he can normalize them first: 
          
  $time=~s{
           #$1    $2    $3      $4    $5    $6     $7
           (\d+)/(\d+)/(\d+)\s+(\d+):(\d+):(\d+)\.(\d+)
          }
          {
           sprintf '%04d/%02d/%02d %02d:%02d:%02d.%3d',
                    $1,  $2,  $3,  $4,  $5,  $6,  $7
          }xe
      or die "Failed to normalize '$time'\n";

        [download]

        --- demerphq
        my friends call me, usually because I'm late....

[reply]
[d/l]
Re: How to compare time in perl
by valdez (Monsignor) on Feb 08, 2003 at 17:48 UTC

    You can use Date::Calc to parse time strings and compare them.

    Ciao, Valerio

[reply]
Re: How to compare time in perl
by Nitrox (Chaplain) on Feb 08, 2003 at 17:46 UTC
    Use the site's search to take a peek at existing nodes that cover this.

    -Nitrox

[reply]

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