Re: Date::Parse - how to correctly parse dates between 1901 and 1969

Solution 1

To handle the $year - 1900 bug mentioned by tangent, I have switched to the Date::Parse strptime function. That allows me to ensure a 4-digit year. It fails for dates before 1000. I address that if it comes up, which is unlikely, but possible.

Here is my updated example script with better formatted output:

#!/usr/bin/perl
#---------------------------------------------------------------------
# format_date.pl
#
# format variable date inputs
#---------------------------------------------------------------------

use strict;
use warnings;

use Date::Parse;
use DateTime;

my $DEFAULT_TIME_ZONE = "GMT";

my @dates = (
    "0618-01-01 00:00:00",
    "1066-10-14 00:00:00",
    "1899-06-24 09:44:00",
    "1900-12-31 23:59:59",
    "1901-01-01 00:00:00",
    "1960-12-31 23:59:59",
    "1966-06-24 09:44:00",
    "1968-12-31 23:59:59",
    "1969-01-01 00:00:00",
    "1969-12-31 23:59:59",
    "1970-01-01 00:00:01",
    "2000-01-01 00:00:00",
    "2017-06-24 23:59:59",
    "2018-06-24 09:44:00",
    "2238-06-24 09:44:00"

);

# define format for printf statements
my $pstr = "%-19s  %02s,%02s,%02s,%02s,%02s,%04s,%01s  %-19s\n";
my $pfrm =  "%19s  %02u,%02u,%02u,%02u,%02u,%04u,%01u  %19s\n";

printf( $pstr, "value", "ss", "mm", "hh", "dy", "mo", "year", "z", "da
+te" );

foreach my $string (@dates) {

    # format datetime field from any valid datetime input
    # default time zone is used if timezone is not included in string
    my @datetime = strptime( $string, $DEFAULT_TIME_ZONE );

    # error if date is not correctly parsed
    if ( scalar @datetime == 0 ) {
        die( "ERROR ====> invalid datetime ($string), " 
                    . "datetime format should be YYYY-MM-DD HH:MM:SS" 
+);
    }

    my ( $ss, $mm, $hh, $day, $month, $year, $zone ) = @datetime;

    if ( $year < 1000 ) { $year += 1900; }

    my %datetimehash = (
        year       => $year,
        month      => $month + 1,
        day        => $day,
        hour       => $hh,
        minute     => $mm,
        second     => $ss,
        nanosecond => 0,
        time_zone  => $zone,
    );

    my $date = DateTime->new(%datetimehash);

    printf( $pfrm, $string, $ss, $mm, $hh, $day, $month, $year, $zone,
+ $date );

}

exit 0;
[download]

Here is the output:

value                ss,mm,hh,dy,mo,year,z  date
0618-01-01 00:00:00  00,00,00,01,00,2518,0  2518-01-01T00:00:00
1066-10-14 00:00:00  00,00,00,14,09,1066,0  1066-10-14T00:00:00
1899-06-24 09:44:00  00,44,09,24,05,1899,0  1899-06-24T09:44:00
1900-12-31 23:59:59  59,59,23,31,11,1900,0  1900-12-31T23:59:59
1901-01-01 00:00:00  00,00,00,01,00,1901,0  1901-01-01T00:00:00
1960-12-31 23:59:59  59,59,23,31,11,1960,0  1960-12-31T23:59:59
1966-06-24 09:44:00  00,44,09,24,05,1966,0  1966-06-24T09:44:00
1968-12-31 23:59:59  59,59,23,31,11,1968,0  1968-12-31T23:59:59
1969-01-01 00:00:00  00,00,00,01,00,1969,0  1969-01-01T00:00:00
1969-12-31 23:59:59  59,59,23,31,11,1969,0  1969-12-31T23:59:59
1970-01-01 00:00:01  01,00,00,01,00,1970,0  1970-01-01T00:00:01
2000-01-01 00:00:00  00,00,00,01,00,2000,0  2000-01-01T00:00:00
2017-06-24 23:59:59  59,59,23,24,05,2017,0  2017-06-24T23:59:59
2018-06-24 09:44:00  00,44,09,24,05,2018,0  2018-06-24T09:44:00
2238-06-24 09:44:00  00,44,09,24,05,2238,0  2238-06-24T09:44:00
[download]

Thank you all for the help. It took a bit to get my head wrapped around this one.

EDIT: Solution 2

Based on discussion with thanos1983, I explored using the Date::Manip module to parse datetimes.

This simplified parsing variable inputs greatly. It even handles 2-digit years correctly.

Here is the updated code and output:

#!/usr/bin/perl
use strict;
use warnings;
use Date::Manip;
use feature 'say';

my $DEFAULT_TIME_ZONE = "GMT";

my @dates = (
    "0618-01-01 00:00:00",    # intpreted as 2518-01-01
    "1066-10-14 00:00:00",
    "1899-06-24 09:44:00",
    "1900-12-31 23:59:59",
    "1901-01-01 00:00:00",
    "1960-12-31 23:59:59",
    "1968-12-31 23:59:59",
    "1969-01-01 00:00:00",
    "1969-12-31 23:59:59",
    "1970-01-01 00:00:01",
    "2000-01-01 00:00:00",
    "2018-02-20 00:00:00",
    "20180220",
    "02/20/2018",
    "02/20/18",    # interpreted as 1918-02-20
    "2018-02-20",
    "2238-02-20 09:44:00"
);

# define format for printf statements
say "Well formatted date  Variable input date";
say UnixDate( ParseDate($_), '%Y-%m-%d %T' ) . qq{  $_} for (@dates);

exit 0;

__END__

$ format_date.pl
Well formatted date  Variable input date
0618-01-01 00:00:00  0618-01-01 00:00:00
1066-10-14 00:00:00  1066-10-14 00:00:00
1899-06-24 09:44:00  1899-06-24 09:44:00
1900-12-31 23:59:59  1900-12-31 23:59:59
1901-01-01 00:00:00  1901-01-01 00:00:00
1960-12-31 23:59:59  1960-12-31 23:59:59
1968-12-31 23:59:59  1968-12-31 23:59:59
1969-01-01 00:00:00  1969-01-01 00:00:00
1969-12-31 23:59:59  1969-12-31 23:59:59
1970-01-01 00:00:01  1970-01-01 00:00:01
2000-01-01 00:00:00  2000-01-01 00:00:00
2018-02-20 00:00:00  2018-02-20 00:00:00
2018-02-20 00:00:00  20180220
2018-02-20 00:00:00  02/20/2018
2018-02-20 00:00:00  02/20/18
2018-02-20 00:00:00  2018-02-20
2238-02-20 09:44:00  2238-02-20 09:44:00
[download]

Comment on Re: Date::Parse - how to correctly parse dates between 1901 and 1969 Select or Download Code

Replies are listed 'Best First'.
Re^2: Date::Parse - how to correctly parse dates between 1901 and 1969 by Anonymous Monk on Feb 20, 2018 at 04:55 UTC
Hi, 1900 + nonsense is the entire reason for modules like DateTime to exist From DateTime `my $formatter = DateTime::Format::Strptime->new(...);` [download] So DateTime::Format::Strptime, DateTime:: Strptime `my $dt = $formatter->parse_datetime( $timestampstring );` [download]	[reply] [d/l] [select]
Re^3: Date::Parse - how to correctly parse dates between 1901 and 1969 by eniad (Acolyte) on Feb 20, 2018 at 15:27 UTC
The input can be in variable formats: `my @dates = ( "2018-02-20 00:00:00", "20180220", "02/20/2018", "02/20/18", # interpreted as 1918-02-20 "2018-02-20" );` [download] Date::Parse handles those (with some massaging). DateTime::Format::Strptime requires well formatted dates to begin with. Am I missing a module of DateTime or Time::Piece that can handle the different input formats?	[reply] [d/l]
Re^4: Date::Parse - how to correctly parse dates between 1901 and 1969 by Anonymous Monk on Feb 20, 2018 at 21:10 UTC
`#!/usr/bin/perl -- use strict; use warnings; use DateTime; use DateTime::Format::Natural; my @dates = ( "2018-02-20 00:00:00", "20180220", "02/20/2018", "02/20/18", # interpreted as 1918-02-20 "2018-02-20", "today", "now", ); my $dfn = DateTime::Format::Natural->new; print $dfn->parse_datetime($_),$/ for @dates; __END__ 2018-02-20T00:00:00 2018-02-20T21:12:19 2018-02-20T21:12:19 2018-02-20T21:12:19 2018-02-20T00:00:00 2018-02-20T00:00:00 2018-02-20T21:12:19` [download]	[reply] [d/l]
Re^4: Date::Parse - how to correctly parse dates between 1901 and 1969 by Anonymous Monk on Feb 20, 2018 at 19:04 UTC
So you simply make up a pattern for each format ... ... Could try ..Format::Natural	[reply]


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