#!/usr/bin/perl -w
use strict;
my %idhash;
my @ids;
foreach (@id_list){
   #split up your input line into something useful
   @ids = split (/-->/,$_);
   # check to see if that date is already in your hash and if it is ne
+wer
   if(defined($idhash{$ids[1]}) &&
   $idhash{$ids[1]} >= $ids[2]){
      next
   }else{
      #populate your hash
      $idhash{$ids[1]} = $ids[2];
   }
}
#then print your dates from the hash using foreach key
[download]

#!/usr/bin/perl
use XML::Simple;
@files = `ls`;
use XML::Parser;
foreach $input_file (@files){
 my $xml_parser = XML::Simple->new();
 my $data = $xml_parser->XMLin($input_file);
 
        my $date = $data->{'root'}->{'date'};
        my $time = $data->{'root'}->{'time'};

}
[download]

How to store only one date file which has large date and time

What have you tried?
If you want to reference the date and time you could look at a structure of arrays or if you want to search by date, hashes.
Most of the monks here will be happier to help if you show what you tried.