#!/usr/bin/perl -w

use Checking;


$here = <<ATM;

1 deposit
2 withdraw
3 current Balance
4 exit

ATM

print $here;
print "Enter the type of transaction you want to do:";
$enter = <STDIN>;

if($enter == '1') {
print "Enter the amount you want to deposit:";
        $mon = <stdin>;
        $d = Checking::deposit($mon);

        print "Deposited Amount: $d\n";
        #&deposit($mon);
                        }

##</code><code>##


package Checking;

my $bal = 0;

sub deposit {
                $d = @_;
                $bal = $bal+$d;
#               print $bal;
                #return;
                }
1;


##</code><code>##


./myATM.pl 

1 deposit
2 withdraw
3 current Balance
4 exit

Enter the type of transaction you want to do:1
Enter the amount you want to deposit:23
Deposited Amount: 1