CODEWITHSUNDEEP
perlswitch-statementcasecontrol-structure
user1444664
user1444664

Reputation:

Perl Case statement for a range of dates

I have this PERL Switch..case statement:

switch ($today)
{ 
    case "14-Aug-2012"  { do A }
    case "15-Aug-2012"  { do B }
}#end switch

My problem is that the "do B" statement is the same for 15-Aug-2012 to like 01-Oct-2012. How do I say case between these dates so I don't have to rewrite the same thing for different days and making my script long?

I've put in the whole script so someone could help me use what I have to manage my question.

use Date::Calc
use Switch

#connect to database...

my @date_today=Today();
my $today=substr(Date_to_Text(@date_today),4,11);

Switch($today)
{
  case "14-Aug-2012" {Do A}
  case "15-Aug-2012" {Do B}
  case ...
  case ...
  case ...
}

The last 3 case statements are supposed to do:

  between 16-Aug-2012 and 28-Sep-2012 {do C}
  between 29-Sep-2012 and 26-Oct-2012 {do D}
  between 27-Oct-2012 and 09-Nov-2012 {do E}

Upvotes: 0

Views: 2799

Answers (3)

dan1111
dan1111

Reputation: 6566

Here is another way of doing it that may be a bit simpler. It simply converts the dates into YYYYMMDD format, which allows them to be sorted/compared numerically.

sub sortable_date
{
    my %months;
    @months{
        'Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'
    } = ('01'..'12');

    if (shift() =~ /^(\d{1,2})-(\w{3})-(\d{4})/ and exists $months{$2})
    {
        return "$3$months{$2}$1";   
    }
    else { die "invalid date format!"; }
}

switch (sortable_date($today))
{ 
    case sortable_date("14-Aug-2012")                  { do A }
    case ($_[0] >= sortable_date("15-Aug-2012") and
          $_[0] <= sortable_date("01-Oct-2012"))       { do B }
}

I would recommend mpe's approach if you are going to be doing a lot with dates in general, though.

Upvotes: 0

mpe
mpe

Reputation: 1000

Use UNIX timestamps instead of date strings. Timestamps are integers and can easily be classified into date ranges (and reformatted using localtime()).

For example, use Time::Local and its timelocal() function to turn your string into a timestamp:

use Time::Local;
my %months = ( # necessary because timelocal() expects month numbers, not strings
  'Jan' => 0,
  'Feb' => 1,
  'Mar' => 2,
  'Apr' => 3,
  'May' => 4,
  'Jun' => 5,
  'Jul' => 6,
  'Aug' => 7,
  'Sep' => 8,
  'Oct' => 9,
  'Nov' => 10,
  'Dec' => 11
);
my $today = '15-Aug-2012';
my @t = $today =~ /(\d{4})-(\w{3})-(\d{4})/;
$t[1] = $months{$t[1]};  # turn string into integer
my $timestamp = timelocal(0, 0, 0, @t[0, 1, 2]); # sec, min, hr, day, month, year

Upvotes: 0

DVK
DVK

Reputation: 129481

Use a software engineering approach.

If you need to do the same thing for an entire range of days, use that range's ID as an discreet value to choose on. Then have a subroutine to tell you what the range ID is that the date falls on:

sub range_for_date {
    my $date = shift;
    # Compute the range value in some discreet subset
    # How to compute it is somewhat irrelevant
    #      and can be asked separately if you have no idea
    # discreet subset can be an index 1..N, ecpoch timestamps,
    # or a somehow-encoded range end date (e.g. "20121001" is easy)
    # For the switch example below we will assume end dates

    return $range_id; # in "20121001" format 
}

switch (range_for_date($today)) {
    case "20121001" { do B; }
    case "20120110" { do A; }
}

Upvotes: 2

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