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#!perl -w
use strict;
=head1 NAME
compound_interest.pl - more advanced one to generate a txt file
=head1 DESCRIPTION
Calculate compound interest given a nest_egg, APR, and duration in years.
=head1 SYNOPSIS
compound_interest.pl [man|help]
compound_interest.pl [nest_egg=<loan_amount>] [apr=<interest>] [duration=<years>] [outfile=<filename>]
=head1 OPTIONS
All options must have a single or double hyphen in front of the name. Only
the minimum name that is unique is required.
=over 4
=item --apr
Rate of interest annually.
=item --duration
Number of years to calculate the loan.
=item --nest_egg
Amount of loan to calculate compounding interest.
=item --outfile
Write to an outfile named filename or to Standard Out.
=item --year
Year to begin the calculation.
=item --help or ?
Show a help page
=item --test
Test all functions.
=back
=head1 EXAMPLES
=head1 NOTES
=head1 AUTHOR
5-1-2012 - Huimin Tao(Helen)
5-4-2012 - extended by David Scott
=cut
package main;
# libraries
use SelfLoader;
use FileHandle;
use Getopt::Long;
use Pod::Usage;
pod2usage(0) if $#ARGV == -1; # no arguments if @ARGV has no entries
# options
# First, we'll set up the variables we want to use.
my $outfile = "interest.txt"; # This is the filename of our report.
my $nest_egg = 10000; # $nest_egg is our starting amount
my $year = 2000; # This is the starting year for our table.
my $duration = 10; # How many years are we saving up?
my $apr = 9.5; # This is our annual percentage rate.
my $help = 0;
my $test = 0;
GetOptions( 'help|?' => \$help,
test => \$test,
"outfile:s" => \$outfile, "nest_egg:i" => \$nest_egg,
"year:i" => \$year, "duration:i" => \$duration,
"apr:f" => \$apr,
);
pod2usage(1) if $help;
pod2usage(-message => 'Spurious argument(s) left: ' . "@ARGV",
-verbose => 1) if $#ARGV != -1;
test() if $test;
print "Writing interest calculation to ", $outfile ? $outfile : "Standard Out", "\n";
my $file = open_report($outfile);
print $file print_headers();
print $file interest_report($nest_egg, $year, $duration, $apr);
print $file report_footer($nest_egg, $duration, $apr);
close $file;
print "Completed writing to ", $outfile ? $outfile : "Standard Out", "\n";
exit(0);
# Functions follow:
#
# my $file_handle = open_report();
sub open_report {
my ($outfile) = @_;
my $file = FileHandle->new();
if ( $outfile ) {
open ($file, ">$outfile") or die("Can't open report: $!");
} else {
open ($file, ">&STDOUT") or die("Can't open report to STDOUT: $!");
}
return $file;
}
# my $text = print_headers();
sub print_headers {
# Print the headers for our report.
return "Year". "\t". "Balance". "\t". "Interest". "\t".
"New balance". "\n";
}
# my $interest = calculate_interest($nest_egg, $apr);
sub calculate_interest {
# Given a nest egg and an APR, how much interest do we collect?
my ($nest_egg, $apr) = @_;
return int (($apr / 100) * $nest_egg * 100) / 100;
}
# my $text = interest_report($nest_egg, $year, $duration, $apr);
sub interest_report {
# Get our parameters. Note that these variables won't clobber the
# global variables with the same name.
my ($nest_egg, $year, $duration, $apr) = @_;
# We have two local variables, so we'll use my to declare them here.
my ($i, $line);
my $result = "";
# Calculate interest for each year.
for $i (1 .. $duration) {
$year++;
my $interest = calculate_interest($nest_egg, $apr);
$line = join("\t", $year, $nest_egg, $interest,
$nest_egg + $interest) . "\n";
$result .= $line;
$nest_egg += $interest;
}
return $result;
}
# my $text = report_footer($nest_egg, $duration, $apr);
sub report_footer {
my ($nest_egg, $duration, $apr) = @_;
my $result = "\n Our original assumptions:\n";
$result .= " Nest egg: $nest_egg\n";
$result .= " Number of years: $duration\n";
$result .= " Interest rate: $apr\n";
return $result;
}
__END__
sub test {
use Test::More tests => 5;
my $headers = "Year\tBalance\tInterest\tNew balance\n";
is( print_headers(), $headers, 'Test header on interest calculation');
# my $interest = calculate_interest($nest_egg, $apr);
my $amount = 50;
is( calculate_interest(1000, 5.0), $amount, 'Calculate interest(1000,5.0)');
# my $text = interest_report($nest_egg, $year, $duration, $apr);
my $report = "2001\t1000\t50\t1050\n". "2002\t1050\t52.5\t1102.5\n" .
"2003\t1102.5\t55.12\t1157.62\n" .
"2004\t1157.62\t57.88\t1215.5\n" .
"2005\t1215.5\t60.77\t1276.27\n";
is( interest_report(1000, 2000, 5, 5.0), $report, 'interest report(1000, 2000, 5, 5.0)');
# my $text = report_footer($nest_egg, $duration, $apr);
my $footer = "\n Our original assumptions:\n" .
" Nest egg: 1000\n" .
" Number of years: 5\n" .
" Interest rate: 5\n";
is( report_footer(1000, 5, 5.0), $footer, 'report footer(1000, 5, 5.0)');
is(1,1,'Dummy Test');
exit(0);
}
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