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

Monks, I'm a little stumped here. I am printing out a sort of list view of a calendar. I'm trying to only print the date heading once if there is more than ne reservation on that date. It would look something like this: 

2020-03-21 | 2:00 pm
                    | 3:00 pm

2020-03-22 | 2:00:pm

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I am looping through, but I can't figure out how to NOT print the date again if it has already been printed. I have something like the following (this is not the actual code): 


$SQL = "SELECT * from $reservations_table where approved!='declined' a
+nd date > '$dateadded2' OR (date = '$dateadded2' and militaryendtime 
+> '$hourmin' and approved!='declined' and approved!='cancelled') orde
+r by date asc, militarytime asc";
&Do_SQL;

$startcount = ($currentpage - 1) * $titlesperpage + 1;
        $stopcount = $currentpage * $titlesperpage;
        $current_count = 0;
        
        while (($pointer = $sth->fetchrow_hashref) && ($current_count 
+<= $stopcount)){
            $current_count++;
            if ($current_count >= $startcount && $current_count <= $st
+opcount) {
            

print <<HTML;
<table border=0 cellpadding=5 cellspacing=5>
<tr>
<td width=100 align=center><b>$date</b></td>
<td  width=100 align=center>$time_lc</td>
<td>-</td>
<td  width=100 align=center>$endtime_lc</td>
<td width=100 align=center>$area</td>
<td width=100 align=center>$unit</td>


</tr>
</table>

}
}

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I tried to set a $lastdate = $date after the loop, then compare it on the next loop but I'm doing something wrong. Any ideas? Thanks!

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Re: Matching Dates
by choroba (Cardinal) on Mar 22, 2020 at 02:26 UTC
    Without seeing the actual code I can't help you with the details, but the general idea is correct: 
    #!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use enum qw( DATE TIME );

my @reservations = ([ '2020-03-21', '2:00 pm' ],
                    [ '2020-03-21', '3:00 pm' ],
                    [ '2020-03-22', '2:00:pm' ]);

my $last_date = "";
for my $reservation (@reservations) {
    print $last_date eq $reservation->[DATE] ? ' ' x 10 : $reservation
+->[DATE];
    say ' ', $reservation->[TIME];
    $last_date = $reservation->[DATE];
}

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    Output: 
    2020-03-21 2:00 pm
           3:00 pm
2020-03-22 2:00:pm

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    map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
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      I wasn't familiar with enum in perl as opposed to C, so I found this interesting to replicate and then supplement from the examples given in enum.pm:

      date is 0
time is 1
2020-03-21 2:00 pm
           3:00 pm
2020-03-22 2:00:pm
6 is SIX
pref is 2
date is Months_Feb 1
c is  22

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      #!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use enum qw( DATE TIME );

say "date is ", DATE;
say "time is ", TIME;

my @reservations = (
  [ '2020-03-21', '2:00 pm' ],
  [ '2020-03-21', '3:00 pm' ],
  [ '2020-03-22', '2:00:pm' ]
);

my $last_date = "";
for my $reservation (@reservations) {
  print $last_date eq $reservation->[DATE] ? ' ' x 10 : $reservation->
+[DATE];
  say ' ', $reservation->[TIME];
  $last_date = $reservation->[DATE];
}

use enum qw(Forty=40 FortyOne Five=5 Six Seven);

# Yes, you can change the start indexs at any time as in C
say "6 is ", "SIX";

use enum qw(:Prefix_ One Two Three);
## Creates Prefix_One, Prefix_Two, Prefix_Three
say "pref is ", Prefix_Three;

use enum qw(
  :Months_=0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  :Days_=0   Sun Mon Tue Wed Thu Fri Sat
  :Letters_=20 A..Z
);
say "date is Months_Feb ", Months_Feb;
say "c is  ", Letters_C;

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