#!/usr/bin/perl 

use strict;
use warnings;
use Data::Dumper;

my @AoH;

my @fields = qw(subject grade rank);

while (my $record = <DATA>){
  chomp $record;
  my @values = $record =~ /([^,]+)/g;
  push @AoH, {
    map {$fields[$_] => $values[$_]} (0..$#fields)
  };
}

print Dumper \@AoH;

__DATA__
english,1,1
history,2,2
science,3,3
biology,4,4

##</code><code>##

---------- Capture Output ----------
> "C:\Perl\bin\perl.exe" _new.pl
$VAR1 = [
          {
            'subject' => 'english',
            'grade' => '1',
            'rank' => '1'
          },
          {
            'subject' => 'history',
            'grade' => '2',
            'rank' => '2'
          },
          {
            'subject' => 'science',
            'grade' => '3',
            'rank' => '3'
          },
          {
            'subject' => 'biology',
            'grade' => '4',
            'rank' => '4'
          }
        ];

> Terminated with exit code 0.