Homework Assignment 8

An Inventory Management Program

CS 1510
Introduction to Computing
Fall Semester 2014

Due: Monday, November 3, at 10:00 AM

Introduction

For this assignment, you will write a new program from scratch. The focus is writing functions and practicing more with file I/O.

Spec 1: Inventory Management

Your client this week is a candy bar distributor that caters to the nostalgia market. This small company distributes just four products: Chunky, Skybar, Valomilk, and Zagnut. It needs a simple program to help it track its inventory of these vintage candy bars.

The program uses three text files:

1. the initial inventory,
2. the week's transactions, and
3. the updated inventory.

Each inventory file consists of four lines, one per product. Each line contains a product name followed by the number of cases of that product in the warehouse. The name and number are separated by whitespace. The order of the four products in the file is not specified; neither is the case used for the candy bar name. For example, here are two possible input files:

    example one              example two
    ---------------          ---------------
    Chunky       12          ZAGNUT 8
    Zagnut        8          VALOMILK 3
    Skybar       19          SKYBAR 19
    Valomilk      3          CHUNKY 12

The transaction file lists all the transactions for the week, both sales to customers and purchases from candy manufacturers. Each line of this file consists of the data for a single transaction.

• A sale transaction line contains, in order, the word sale, one of the four product names, and a positive whole number of cases of this product sold to a customer.


• A purchase transaction line contains, in order, the word purchase, one of the four product names, and a positive whole number of cases of this product purchased from a manufacturer.

As with the inventory files, the data on each line are separated by whitespace, and the case used for the transaction types and candy bar names is unspecified. For example, here are a few possible transaction lines:

    sale chunky 1
    PURCHASE  ZAGNUT   8
    Sale      zagnut   8
    SALE VALOMILK 3
    Purchase chunky 5

The program must take the following input from keyboard:

• the name of the file with the week's beginning inventory,
• the name of the file containing the week's transactions, and
• the name of the file in which to write the week's closing inventory.

In addition to producing an output file that lists the week's closing inventory, the program must also print to the screen:

• a table displaying the week's beginning inventory,
• the number of sales transactions processed,
• the number of purchase transactions processed, and
• a table displaying the week's ending inventory.

You may assume the following:

• The user enters valid file names.
• The input files exist.
• The data in the input files conforms to the specifications given above.
• A sale transaction never results in a negative inventory value.

Here is some design and programming advice:

• Create several input files to test your program. Verify the results by hand. (I will use test data files that are too large to make hand calculation of the results convenient.)


• Break the problem into high-level operations that need to be done. Implement and test each, one at a time.


• Use functions to implement your high-level operations. This will make your program easier to understand, and it will enable you to avoid duplicating code. For example, your program needs to display to the screen both the beginning inventory and the closing inventory. A single function can do both.


• Give your functions and formal parameters names that are clear and descriptive. Use comments to explain any idea that your names cannot communicate.


• Use the string method split() with no arguments to break your input lines into parts. Use parallel assignment to assign the resulting values to variables.


• Close each data file as soon as your program is finished using it.

Name your program candybar_inventory.py.

Demonstration of Correctness

Start a fresh Python shell. Run the final version of your program on at least three sets of input files for beginning inventory and transactions. These input files should demonstrate that your program satisfies the program specification.

Save your shell to a text file named interactions.py.

Deliverables

By the due date and time, submit:

• interactions.py
• candybar_inventory.py

Use the on-line submission system.

Make sure that your program meets the course programming standards.