IT 210 Week 2 Volume of a Cylinder Assignment

University of Phoenix Associates Program Material (revised by Albert Mink)

Worksheet D

System-Level Requirements Example

Consider the Sale Price problem from Chapter 2, page 75, in which you read what are often called system-level requirements—the basis for all subsequent analysis and design steps. The following steps will take these system-level requirements and refine them into analysis and pseudocode for the program.

Up to this point, you have identified the processes the program must perform, but you have not given any consideration to exactly how the processes work together to solve the problem. At this point, you must generate a description of the processing using pseudocode, a natural language description of the processing the application must perform.

The natural place to start is the system-level requirements you identified in the Input-Process-Output (IPO) chart. Determine how the processes work together: Once you have determined the top-level logic, you can then design each of the individual processes. It is this step-wise refinement process that allows you to conceptualize a vague problem into increasing levels of details in order to actually generate a working program. This point is important because the step-wise refinement pattern is used throughout the entire program development—each new piece of information is based on, and is a refinement of, the information uncovered in the previous step.

The following information demonstrates how to write a program to calculate the total cost of an item on sale (including the discount and sales tax). Comments in the program are prefixed with two forward slashes (//).

Analysis

Process:

1. Get user input

2. Calculate discount

3. Calculate discounted price

4. Calculate sales tax

5. Calculate total price

6. Display total price

ItemName (String)

OriginalPrice (Float)

DiscountPercentage (Float)

SalesTaxPercentage (Float)

User Input:

Output:

TotalPrice (Float)

Pseudocode

Main Module

// Declare global variables that are used in more than one module

Declare OriginalPrice As Float

Declare DiscountPercentage As Float

Declare Discount As Float

Declare SalesTaxPercentage As Float

Declare SalesTax As Float

Declare DiscountedPrice As Float

Declare TotalPrice As Float

// Call submodules

Call Get User Input Module

Call Calculate Discount Module

Call Calculate Discounted Price Module

Call Calculate Sales Tax Module

Call Calculate Total Price Module

Call Display Total Price Module

End Program

Get User Input Module

// Declare a local variable that is only used in this module

Declare ItemName As String

// State the purpose of the program to the user

Write “This program displays the total price of an item after “

Write “the discount and sales tax have been applied.”

// Get the name of the item

Write “What is the name of the item?”

Input ItemName

// Get the original price of the item from the user

Write “What is the original price?”

Input OriginalPrice

// Get the discount percentage from the user

Write “What is the discount percentage?”

Input DiscountPercentage

// Get the sales tax percentage from the user

Write “What is the sales tax percentage?”

Input SalesTaxPercentage

Calculate Discount Module

// Calculate the amount of the discount

Set Discount = OriginalPrice * DiscountPercentage / 100

Calculate Discounted Price Module

// Calculate the discounted price

Set DiscountedPrice = OriginalPrice - Discount

Calculate Sales Tax Module

// Calculate the amount of the sales tax

Set SalesTax = DiscountedPrice * SalesTaxPercentage / 100

Calculate Total Price Module

// Calculate the total price

Set TotalPrice = DiscountedPrice + SalesTax

Display Total Price Module

// Display the result to the user

Write “The total price of the “ + ItemName + “ is $” + TotalPrice

Sample Output

(User input to the program is displayed in bold.)

This program displays the total price of an item after

the discount and sales tax have been applied. What is the name of the item?

perfume

What is the original price?

30.00

What is the discount percentage?

20

What is the sales tax percentage?

6

The total price of the perfume is $25.44

IT 210