Problem 3

Trish at Bargain Used Books has been using the programs you developed for her and really likes them. Recently however, she hired a new cashier who isn't very good at data entry. In particular, she needs the program to catch data entry errors that are made and give the user a chance to reenter the data.

To help her out, you'll be taking the first program you developed for her (Lab 01 Problem 4) and rewrite it so that it blocks out some data entry errors. Here's the changes that she'd like to see:

• A user should never be able to enter a negative number for the number of paperbacks, hardbacks, or magazines that are being purchased. Zero is a valid entry.
• It is extremely rare that someone buys a LOT of a particular item, so Trish wants the program to limit the number of each item type someone can purchase. These are the limits she wants to set:
  • Paperbacks: Maximum of 50
  • Hardbacks: Maximum of 20
  • Magazines: Maximum of 35

Other than these checks on the data entry, the program should execute as it did before.

NOTE: We are not handling issues where a user types an invalid integer, that is, an entry which cannot be converted using the int() function. We will handle that in a future lab.

Create a file named Lab03P3.py. Write a program that calculates the cost for the total purchase:

• Ask the user to enter the number of paperbacks, hardbacks, and magazines being purchased.
• If the user enters a negative number, or goes above the maximum for a particular item, the program should continue to ask the user to enter a number until it is valid.
• Calculate the total before tax.
• Calculate the amount of sales tax on the total.
• Calculate the total after tax.
• Output the total before tax, the sales tax, and the total after tax.

• Remember to format monetary amounts with 2 digits after the decimal.

  NOTE: There are no discounts in this program.

Information to use for this problem from Lab 01 Problem 4:

Trish at Bargain Used Books has hired you to write a Python program that will help her calculate what a customer should pay. She has a very simple price structure:

Paperback books are $2.50 each.

Hardback books are $7.00 each.

Magazines are $3.95 each.

With every purchase, Trish also must charge 7% sales tax on the total.