#!/usr/bin/perl -w
    use strict;

    use constant EXPENSE_FILE      => 'expense.dat';
    use constant EXPENSE_REPORT    => 'final_expense.txt';
    use constant FIELDS_PER_RECORD => 4;
    use constant REPORT_HEADER     => "Department,Total\n";

    open IN_FILE, "<", EXPENSE_FILE
        or die "Cannot open ".EXPENSE_FILE." for reading: $!";
    my @expenses = <IN_FILE>;
    close IN_FILE;

    my %deptTotals;

    foreach my $expense ( @expenses ) {
        my %record;
        my @fields = qw/ dept empID amount desc /;
        @record{ @fields } = split /,/, $expense, FIELDS_PER_RECORD;
        if ( ! exists $deptTotals{ $record{ dept } } ) {
            $deptTotals{ $record{ dept } } = 0;
        }
        $deptTotals{ $record{ dept } } += $record{ amount };
    }

    open OUT_FILE, ">", EXPENSE_REPORT
        or die "Cannot open ".EXPENSE_REPORT." for writing: $!";

    print OUT_FILE REPORT_HEADER;
    foreach my $dept ( sort keys %deptTotals ) {
        print OUT_FILE "$dept,$deptTotals{ $dept }\n";
    }
    close OUT_FILE;

##</code><code>##

    #!/usr/bin/perl -w
    use strict;

    use constant EXPENSE_FILE      => 'expense.dat';
    use constant EXPENSE_REPORT    => 'final_expense.txt';
    use constant FIELDS_PER_RECORD => 4;
    use constant REPORT_HEADER     => "Department,Total\n";

    my $expenses   = get_expense_data( EXPENSE_FILE );
    my $deptTotals = sum_expenses_by_department($expenses, FIELDS_PER_RECORD);
    write_report( $deptTotals, EXPENSE_REPORT, REPORT_HEADER );

    sub get_expense_data {
        my $file = shift;
        open IN_FILE, "<", $file or die "Cannot open $file for reading: $!";
        my @expenses = <IN_FILE>;
        close IN_FILE;
        return \@expenses;
    }

    sub sum_expenses_by_department {
        my ( $expenses, $fields_per_record ) = @_;
        my %deptTotals;

        foreach my $expense ( @$expenses ) {
            my %record;
            my @fields = qw/ dept empID amount desc /;
            @record{ @fields } = split /,/, $expense, $fields_per_record;
            if ( ! exists $deptTotals{ $record{ dept } } ) {
                $deptTotals{ $record{ dept } } = 0;
            }
            $deptTotals{ $record{ dept } } += $record{ amount };
        }
        return \%deptTotals;
    }

    sub write_report {
        my ( $report_data, $file, $header ) = @_;
        open OUT_FILE, ">", $file or die "Cannot open $file for writing: $!";

        print OUT_FILE $header;
        foreach ( sort keys %$report_data ) {
            print OUT_FILE "$dept,$report_data->{ $_ }\n";
        }
        close OUT_FILE;
    }

##</code><code>##

    my $expenses   = get_expense_data( EXPENSE_FILE );
    my $deptTotals = sum_expenses_by_department( $expenses, FIELDS_PER_RECORD );
    write_report( $deptTotals, EXPENSE_REPORT, REPORT_HEADER );

##</code><code>##

    use constant EXPENSE_FILE      => 'expense.dat';
    use constant EXPENSE_REPORT    => 'final_expense.txt';
    use constant FIELDS_PER_RECORD => 4;
    use constant REPORT_HEADER     => "Department,Total\n";
    use constant ERROR_REPORT      => 'expense_error.txt';
    use constant ERROR_HEADER      => "Department,Employee,Total,Description\n";
    use constant EXCESSIVE         => 200;

    my $raw_expenses                 = get_expense_data( EXPENSE_FILE );
    my ( $expenses, $largeExpenses )
        = split_normal_from_excessive( $raw_expenses, EXCESSIVE );
    my $deptTotals = sum_expenses_by_department($expenses, FIELDS_PER_RECORD);
    write_report( $deptTotals, EXPENSE_REPORT, REPORT_HEADER );
    write_report( $large_expenses, ERROR_REPORT, ERROR_HEADER );