A Simple Program

We are going to apply what we have learned so far to create a simple program called currency converter.

We will use a hash to store the exchange rates.
To get the inputs from users via the command line, we will use <STDIN>. We use the chomp() function to remove the newline character (\n) from the user’s inputs.
We convert the amount from local currency to foreign currency if the currencies are supported.

#!/usr/bin/perl
use warnings;
use strict;

my ($l_curr, $f_curr, $l_amount, $f_amount);

my %rates = (
     USD => 1,
     YPY => 82.25,
     EUR => 0.78,
     GBP => 0.62,
     CNY => 6.23
);

# print supported currencies
print("Supported currency:\n");
for (keys %rates) {
	print(uc($_),"\n");
}

# get inputs from users:
print("Enter local currency:\n");
$l_curr = <STDIN>;

print("Enter foreign currency:\n");
$f_curr = <STDIN>;

print("Enter amount:\n");
$l_amount = <STDIN>;

chomp($l_curr,$f_curr,$l_amount);

# check user's inputs.
if (not exists $rates{$l_curr}) {
     print("Local currency is not supported\n");
} elsif (not exists $rates{$f_curr}) {
     print("Foreign currency is not supported\n");
} else {
     # convert from local currency to foreign currency
     $f_amount = ($rates{$f_curr} / $rates{$l_curr}) * $l_amount;

     # print out the result
     print("$l_amount $l_curr = $f_amount $f_curr","\n");
}