my @dates = (
	"1901-01-01 00:00:00",
    "1968-12-31 23:59:59",
    "1969-01-01 00:00:00",
    "1969-12-31 23:59:59",
    "1970-01-01 00:00:01",
);
for my $string (@dates) {
    my $epoch = str2time( $string, 'GMT' );
	print "$string ($epoch seconds)\n";
    my $date = DateTime->from_epoch( epoch => $epoch );
	print $date->ymd, " ", $date->hms, "\n\n";
}

##</code><code>##

1901-01-01 00:00:00 (978307200 seconds)
2001-01-01 00:00:00

1968-12-31 23:59:59 (3124223999 seconds)
2068-12-31 23:59:59

1969-01-01 00:00:00 (-31536000 seconds)
1969-01-01 00:00:00

1969-12-31 23:59:59 (-1 seconds)
1969-12-31 23:59:59

1970-01-01 00:00:01 (1 seconds)
1970-01-01 00:00:01

##</code><code>##

use Time::Local;

my %hash = (
	"1901-01-01 00:00:00" => [00,00,00,01,00,1901],
    "1968-12-31 23:59:59" => [59,59,23,31,11,1968],
    "1969-01-01 00:00:00" => [00,00,00,01,00,1969],
    "1969-12-31 23:59:59" => [59,59,23,31,11,1969],
    "1970-01-01 00:00:01" => [01,00,00,01,00,1970],
);
for my $string (@dates) {
    my $array = $hash{$string};
    my $epoch = timegm( @$array );
	print "$string ($epoch seconds)\n";
    my $date = DateTime->from_epoch( epoch => $epoch );
	print $date->ymd, " ", $date->hms, "\n\n";
}

##</code><code>##

1901-01-01 00:00:00 (-2177452800 seconds)
1901-01-01 00:00:00

1968-12-31 23:59:59 (-31536001 seconds)
1968-12-31 23:59:59

1969-01-01 00:00:00 (-31536000 seconds)
1969-01-01 00:00:00

1969-12-31 23:59:59 (-1 seconds)
1969-12-31 23:59:59

1970-01-01 00:00:01 (1 seconds)
1970-01-01 00:00:01