Programming Fundamentals/Functions/Return Values

A return statement causes execution to leave the current function and resume at the point in the code immediately after where the function was called. Return statements in many languages allow a function to specify a return value to be passed back to the code that called the function. This activity introduces return values. This activity will help you understand how to use return values in a program.

Objectives



 * Understand function return values.
 * Understand how function return values are specified in a program.
 * Single-step through a program to observe function return values.

Prerequisites
Learners should already be familiar with functions and parameters.

Introduction
Review the flowchart example on the right.

Questions

 * What syntax is used to return a value from a function?
 * How are return values defined inside a called function?
 * How are return values referenced from the calling function?

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 display local variables and step through the program one shape at a time.
 * 6) Working together, create a list of function return values 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 function return values.
 * 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?