This is an assignment turned in for a programming languages class. It was meant to be a simple introduction to Perl and I wrote it fairly simply. However, I am curious if anyone has thoughts on the code and/or any ideas for more "creative" :) ways to accomplish the problem. Again, I am not asking for help to solve the assignment since it has already been completed, just seeking constructive criticism. :)

Here's the assignment:

Given an input file of the following format

Firstname Lastname list_of_grades(any number of grades)

You should output

Lastname, Firstname Average list_of_grades

The output should be sorted on lastname, followed by first name to break ties on lastnames. Also, the report should mark any students whose average is at least 20% less than the median class average.

Sample Input File

David Allen 50 60 70
Jane Aardmore 100 100 100
John Smith 75 74 72 73 89
Carl Allen 25 100 100 20
Mike Jones 80 85 82 89 88 86 80


Here's my code.

#---------------------------------------------------------------------
+-----
#-- Author: Adam McManus
#-- Date: 2/10/03
#-- File: program2.pl
#-- Description: 
#--
#---------------------------------------------------------------------
+-----
use strict;

#-- Check usage
die "Usage: $0 input_file\n" if( scalar(@ARGV) != 1 );

#-- Get cmd line arguments
my $input_file = $ARGV[0];    #-- file containing student info

#-- Declare variables
#--------------------------------------------------------------
#-- %students is a hash of student information, indexed by name
#-- $students{last,first}{grades} is the array of grades
#-- $students{last,first}{avg_grade} is the student's average
#--------------------------------------------------------------
my %students;            
my @averages;        #-- sorted array of student averages
my @buffer;        #-- buffer to read line from file into
my $name_index;        #-- index for %students "lastname,firstname"
my $median_class_avg;    #-- median class average

#-- Open the input file 
open(INPUT, '<', $input_file) or die "Couldn't open $input_file: $!\n"
+;

#-- Read the input file one line at a time
while( <INPUT> )
{
   next if( /^$/ );    #-- skip blank lines
   @buffer = split;    #-- split on whitespace

   $name_index = "$buffer[1],$buffer[0]";    #-- create the name index

   #-- Load the student's grades and begin computing the average
   #-- by summing up the student's grades
   foreach my $i ( 2 .. $#buffer )
   {
      push @{ $students{$name_index}{grades} }, $buffer[$i];
      $students{$name_index}{avg_grade} += $buffer[$i];
   } 

   #-- Finish computing the student's average by dividing by number of
+ grades
   $students{$name_index}{avg_grade} /= scalar(@{ $students{$name_inde
+x}{grades} });

   #-- Store the average into the class averages
   push @averages, sprintf("%.1f", $students{$name_index}{avg_grade});
}

#-- Close the input file
close(INPUT) or warn "Warning! $input_file was not closed properly: $!
+\n";

#-- Sort the array of averages numerically for median purposes
@averages = sort { $a <=> $b } @averages;

#-------------------------------------------------------
#-- Find the class median
#-- If even number of grades, take the average of the
#-- middle two grades
#-- Else, take the middle grade
#-------------------------------------------------------
if( scalar(@averages) % 2 == 0 )
{
   my $i = scalar(@averages) / 2;
   $median_class_avg = ( $averages[$i] + $averages[$i - 1] ) / 2;
}
else
{
   my $i = sprintf("%d", scalar(@averages) / 2 );
   $median_class_avg = $averages[$i];
}

#-- Print the header for final report
printf "\n%21s%16s%11s\n", 'Name', 'Average', 'Grades';
print '-' x 79 . "\n"; 

#-- Print the student info
foreach my $name ( sort keys %students )
{
   #-- split out the first and last name of students
   my ($last, $first) = split(',', $name);

   #----------------------------------------
   #-- Check if the student's avg is lower 
   #-- than median class average and flag
   #-- if it is
   #----------------------------------------
   if( $students{$name}{avg_grade} < ($median_class_avg * 0.8) )
   {
      printf "**<.8med** %8s, %-10s", $last, $first;  
   }
   else
   {
      printf "%10s %8s, %-10s", ' ', $last, $first;
   }

   #-- Print student's average
   printf "%5.1f%2s", $students{$name}{avg_grade};

   #-- Print student's grades
   foreach ( 0 .. $#{ $students{$name}{grades} } )
   {
      printf "%4d", $students{$name}{grades}[$_];
   }
   print "\n";
}

#-- Print the number of students and class median average
printf "\nNumber of students processed: %d\n", scalar(@averages);
printf "Median Average: %4.1f\n", $median_class_avg;

print '-' x 79 . "\n";

#-- Program End

[download]


Thanks,
Inelukii

In reply to Style and Coding criticism requested by inelukii

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