Something like this: 
my $data = <<EOD;
Student Id Class John 23 2 Mark 33 3 Jerry 44 2 Sam 55 2 Tom 65 3 Test
+stud 28 2
EOD

my %h;
my @arr = split /\s+/, $data ;
for (my $c=3; $c<($#arr);$c+=3) {
  push @{$h{$arr[$c+2]}}, $arr[$c];
}
print $_."=".join(",",@{$h{$_}})."\n" for (keys %h);

[download]
Output: 
3=Mark,Tom
2=John,Jerry,Sam,Teststud

[download]

In reply to Re: Data Structure by Anonymous Monk
in thread Data Structure by efficasy

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