Programming Fundamentals/Functions/Functions

A function is a sequence of program instructions that performs a specific task, packaged as a unit. Depending on the programming language, a function may be called a subroutine, a procedure, a routine, a method, or a subprogram. The generic term, callable unit, is sometimes used. This activity introduces functions. This activity will help you understand how to use functions in a program.

Objectives

• Understand function concepts.
• Understand how functions are specified in a program.
• Single-step through a program to observe function execution.

Prerequisites

Learners should already be familiar with a visual programming environment.

Introduction

DisplayHello function

DisplayHello function

Review the flowchart example on the right.

Questions

• What flowcharting symbol is used to call a function?
• What syntax is used to call a function?
• What naming convention is used to identify functions?

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 to verify that it works correctly.
4. Trade places, so that both partners have an opportunity to "drive" the visual programming environment.
5. Change the environment to use a slow run speed and/or step through the program one shape at a time.
6. Working together, create a list of function names that would be used to follow the input-process-output model and convert Fahrenheit temperature to Celsius.

Applications

• Identify specific steps which must be followed when creating a program using functions.
• 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?