Re: Subtracting and Comparing Two Dates

[ikegami]

# Always use gmtime and timegm when
# dealing with dates without times.

use Time::Local qw( timegm );

# Replace with your input.
my $then_date_str = 'YYYYMMDD';

my $then_date = do {
   my ($y, $m, $d) = $then_date_str =~ /^(.{4})(.{2})(.{2})\z/;
   $m--;
   timegm(0, 0, 0, $d, $m, $y)
};

my $now_date = do {
   my ($y, $m, $d) = (localtime())[5,4,3];
   timegm(0, 0, 0, $d, $m, $y)
};

my $diff = $now_date - $then_date;
my $diff_days = int($diff / (24*60*60));

if    ($diff_days <  -1) { printf("%d days ago\n", -$diff_days); }
elsif ($diff_days == -1) { print("yesterday\n"); }
elsif ($diff_days ==  1) { print("tomorrow\n"); }
elsif ($diff_days >   1) { printf("%d days from now\n", $diff_days); }
else                     { print("today\n"); }

Notes:

• Time::Local is a core module.
• I advise against this method. Use Date::Calc.
• It only supports dates time can return.

Update: Oops, I was subtracting from $m twice. Fixed.

[BaldPenguin]

For my own clarification, what benefits are there to using Time::Local instead of POSIX. The functionality seems to be the same. Is implemetation different? Or is it just a preference thing?

[ikegami]

I don't see anything in POSIX similar to Time::Local's timegm. To which POSIX function were you refering?

[BaldPenguin]

timegm() in Time::Local == gmtime() in POSIX

After looking it looks like Time::Local is a Pure Perl interface to the Perl localtime objects where POSIX is an XS interface to the system libraries.

[mindful07]

Right now I do not have Date::Calc installed and I'm trying to figure out how I can get the value in days of two dates. Here is my code to give you an idea of what I'm trying to accomplish.

If I somehow can get date::calc installed could I just then do $diff_in_days = Delta_days($sysdate, $installed_date)? Also in the event I can't install date::Calc can you please give a suggestion of how else to accomplish this?

use POSIX qw(strftime);
use Time::Local;
#use Date::Calc qw(:all);
#use time::Piece;
#use Date::Calc qw(Delta_Days);

sub give_warning
{
  my($carrier) = @_;
  my($installed_date);
  my($max_days) = 15;
  $installed_date = get_value($carrier ."_DAYS", $trn_info, '') ;
  printf("Value of Carrier Days is $installed_date \n");
     if ($installed_date ne "" )

     {          
        my $sysdate = decode_date ('SYSDATE','CCYYMMDD');
        printf("Todays date is $sysdate \n");

       my $diff_in_days = $sysdate - $installed_date ;

       print "Difference in days: $diff_in_days\n";

       if $result > $max_days
         # give error and return
       {
         &print_error ("New Installation is required.");
         return 1;
        } 
       elsif $result  <= $max_days
         # give warning and return
      {
       &print_warning ("New Installation is required.");
       return 0;
       }
     }
     else 
     {
     return 0;
     }
}

[ikegami]

Why do you want me to look at this? The code in the post to which you replied does exactly what you want.

[mindful07]

I apologize. I've tried so many suggestions and I thought when I tried to use local:time(timegm) it had given me an error when i tried to include it. It works just fine. Thanks again for your help!