Second Summer 2002

Please write your name or username here: __________________________________

This exam has two parts:

1. Solve the problem below, turn your solution at the end of time.
2. Implement your solution and post it on-line by Mon Jul 15 17:00:00 EST 2002.

• the written part counts as 40% of the grade
• the implementation counts as 60% of the grade

The exam is open-book, open-notes. Here's the problem; consider the following Perl program:

#!/usr/bin/perl

print "Welcome to the machine. We sell stamps. \n"; 
print "10-stamps books are now \$3.70 each and we accept coins.\n"; 
print "Please start entering coins: "; 

$credit = 0; 

while ($line = <STDIN>) {
  chop($line); 
  if    ($line =~ /^dollar$/ ) { $credit += 100; }
  elsif ($line =~ /^quarter$/) { $credit +=  25; }
  elsif ($line =~ /^dime$/   ) { $credit +=  10; }
  elsif ($line =~ /^nickel$/ ) { $credit +=   5; }
  elsif ($line =~ /^cent$/   ) { $credit +=   1; }
  else { print " We don't accept/understand ***(", $line, ")***\n"; }
  print "Your credit now is: ", $credit, " cents.\n"; 
  if ($credit >= 370) {
    print "Great, the stamps are yours.\n"; 
    if ($credit > 370) {
      print "Your change is: ", ($credit - 370), " cents.\n"; 
    } 
    last; 
  } else {
    print "You still need to provide ", 
          (370 - $credit), " cents to get the stamps.\n"; 
    print "Please enter coin: "; 
  }
}

frilled.cs.indiana.edu%vending
Welcome to the machine. We sell stamps. 
10-stamps books are now $3.70 each and we accept coins.
Please start entering coins: dime
Your credit now is: 10 cents.
You still need to provide 360 cents to get the stamps.
Please enter coin: dollar
Your credit now is: 110 cents.
You still need to provide 260 cents to get the stamps.
Please enter coin: dollar
Your credit now is: 210 cents.
You still need to provide 160 cents to get the stamps.
Please enter coin: quarter
Your credit now is: 235 cents.
You still need to provide 135 cents to get the stamps.
Please enter coin: dollar
Your credit now is: 335 cents.
You still need to provide 35 cents to get the stamps.
Please enter coin: nickel
Your credit now is: 340 cents.
You still need to provide 30 cents to get the stamps.
Please enter coin: cent
Your credit now is: 341 cents.
You still need to provide 29 cents to get the stamps.
Please enter coin: cent
Your credit now is: 342 cents.
You still need to provide 28 cents to get the stamps.
Please enter coin: quarter
Your credit now is: 367 cents.
You still need to provide 3 cents to get the stamps.
Please enter coin: dime
Your credit now is: 377 cents.
Great, the stamps are yours.
Your change is: 7 cents.
frilled.cs.indiana.edu%

http://burrowww.cs.indiana.edu:102xx/cgi-bin/exams/midterm

where 102xx is your web server port number.

Graduate Standing:

• add a reset button (or, rather, function) to your web program, OR
• implement it twice once using PHP with sessions, and then using CGI with Perl.
• (choose one or the other but not both)