#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my $sdata = 'student.data';
my %students;
open my $infile, '<', $sdata or die "Cannot open $sdata:$!\n";

while (my $line = <$infile>) {
    chomp($line);
    my ($id,$name,$f3,$f4) = $line =~ m/^(\d+)\s(.*)\s(..)\s(..)$/;
    $students{$name}{id} = $id;
    $students{$name}{f3} = $f3;
    $students{$name}{f4} = $f4;
}

close $infile;

print Dumper(\%students);

##</code><code>##

$VAR1 = {
          'Smith Tom' => {
                           'f3' => 'RM',
                           'id' => '777666555',
                           'f4' => 'So'
                         },
          'Johnson Lee' => {
                             'f3' => 'IE',
                             'id' => '555444333',
                             'f4' => 'Sr'
                           },
          'Jones Mary' => {
                            'f3' => 'SD',
                            'id' => '111222333',
                            'f4' => 'Fr'
                          }
        };

##</code><code>##

for my $student (sort {$students{$a}{id} <=> $students{$b}{id}} keys %students) {
    print "$student => $students{$student}{id}\n";
}