CSC111 Lab 3 2015

--D. Thiebaut (talk) 21:22, 9 February 2015 (EST)

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Teller Machine Program

This section will get you to write a program similar (though not necessarily the same) to the program we wrote in class on Monday. The program takes an integer (without a decimal part) amount of dollars and figures out how to break it down into the least number of 20-, 10-, 5-, and 1-bills.

Reviewing the Division Operators, // and %

Use the Python shell, and try to predict the result of the following operations.

>>> 21 // 5

>>> 21 % 5

>>> 9 // 2

>>> 9 % 2

>>> 13 // 3

>>> 13 % 3

>>> 139 // 20

>>> 139 % 20 

Beginning Program

• Write a program that contains
  • a short header with the program name (lab3.py, for example),
  • your name,
  • the date, and
  • A short description of the program.
• Create 3 different comment lines that will create an outline of your program.

# lab3.py
# yourName
# date
# blah blah blah blah blah blah...
#

# get the initial amount

# compute number of bills

# output number of bills to give out

• Save and Run the program, just to make sure you do not have a syntax error.

Define original amount

• Under the #get the initial amount comment, create a variable called amount and initialize it with a value of your choice. Pick a value that is not a multiple of 5.
• Add a print() statement under the #output number of bills comment, and make it print the amount the user wants to withdraw.
• Verify that your program works.

Compute the number of $20s to give out

• Using the right operator (//, /, or %), make your program compute the number of $20 and store that value in a new variable, called no20s. Add this code under the # compute number of bills.
• Make your program output the no20s variable in the output section.
• Verify that your program works.

Computing the Left-Over Amount

• Go back to the computation of the number of $20s, and compute the amount of money left over once the $20s are taken out of the amount. You have several ways of doing this. You can do it using the % modulo operator, or using multiplication and subtraction. Whichever method you use is fine for today.
• Make your program output the left-over amount, just to make sure that value is computed correctly.
• Verify that your program works fine.

Computing the Remaining Quantities

• Now that you have the structure for your program, add enough Python code to make your code display
  • The total amount
  • The number of $20-bills
  • The number of $10-bills
  • The number of $5-bills
  • The number of $1-bills

• Verify that your program works. Below is a typical output you should try to emulate:

Amount to withdraw =  97

Please lift keyboard and find: 
4 $20-bill(s)
1 $10-bill(s)
1 $5-bill(s)
2 $1-bill(s)

Flexibility and Adaptability

Imagine that your program will be used in an area where the bills do not come in 20, 10, 5 or 1 denominations, but in 100, 50, 10, and 1.

Figure out a way to make the least amount of change to your program so that it now outputs the correct break down for any amount, but in $100-, $50-, $10- and $1-bills.

Make sure your program works! Below is the output of the program if the amount is set to $97:

Amount to withdraw = $ 97

Please lift keyboard and find: 
0 $ 100 bill(s)
1 $ 50 bill(s)
4 $ 10 bill(s)
7 $ 1 bill(s)

Challenge #1: A Change Machine

• Using a similar approach, write a program that, given some number of pennies, will output the correct number of quarters, dimes, nickels, and pennies. You should initialize the amount of pennies with an integer, like this:

 pennies = 84

• Here is an example of what your program should output for 84 pennies:

Amount to withdraw = 84 penny or pennies

Please lift keyboard and find: 
3 quarter(s)
0 dime(s)
1 nickel(s)
4 cent(s)