Programming Fundamentals/Variables/Input-Process-Output Model

The input–process–output (IPO) model is a widely used approach in systems analysis and software engineering for describing the structure of an information processing program or other process. This activity introduces the IPO model using a simple calculation. This activity will help you understand how to design a simple program.

Objectives

 * Understand the input-process-output model.
 * Create a simple program using a visual programming environment.

Prerequisites

 * Review Creating Flowcharts.
 * Review MathsIsFun: Temperature Conversion.
 * The formulas for temperature conversion are:
 * C = (F - 32) * 5 / 9
 * F = C * 9 / 5 + 32
 * An operator is a character or symbol used to perform an arithmetic, logical, or bitwise operation on one or more operands.
 * String concatenation is the joining of character strings end-to-end.
 * An assignment statement sets and/or re-sets the value stored in the storage location(s) denoted by a variable name; in other words, it copies a value into the variable.

Introduction
Review the flowchart example on the right.

Questions

 * What flowcharting symbol is used to indicate the beginning and ending of a program?
 * What flowcharting symbol is used to indicate annotations or comments?
 * What flowcharting symbol is used to indicate variable declaration?
 * What flowcharting symbol is used to indicate input and output?
 * What flowcharting symbol is used to indicate a process or calculation?
 * What operator is used for addition, subtraction, multiplication, and division?
 * What operator is used for assignment?
 * What operator is used for string concatenation?

Activity
With a partner, perform the following:
 * 1) Using a visual programming language, create a program matching the flowchart on the right.
 * 2) Save the program.
 * 3) Test the program with known Fahrenheit-Celsius temperature pairs to make sure it works correctly.
 * 4) Trade places, so that both partners have an opportunity to "drive" the visual programming environment.
 * 5) Copy the program and change it so that it performs the opposite calculation, converting Celsius temperatures to Fahrenheit.
 * 6) Save the program.
 * 7) Test the program with known Celsius-Fahrenheit temperature pairs to make sure it works correctly.

Applications

 * Identify specific steps which must be followed when creating a program using the Input-Process-Output model.
 * Discuss your activity experience with your classmates. What surprised you? What have you learned that you can apply to your own school or work environment?