Programming Fundamentals/Loops/While Loops
Jump to navigation Jump to search
A while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. The while loop can be thought of as a repeating if statement. This activity introduces while loops. This activity will help you understand how to use while loops in a program.
Objectives[edit | edit source]
- Understand while loop concepts.
- Understand how while loops are specified in a program.
- Single-step through a program to observe while loop execution.
Prerequisites[edit | edit source]
Learners should already be familiar with conditions.
Introduction[edit | edit source]
Review the flowchart example on the right.
Questions[edit | edit source]
- What flowcharting symbol is used to indicate a while loop?
- How are while loops structured?
Activity[edit | edit source]
With a partner, perform the following:
- Using a visual programming language, create a program similar to the flowchart on the right based on the following steps.
- Start by creating a while loop that counts from 1 to 5 by 1.
- Save the program.
- Test the program to verify that it works correctly.
- Modify the program to count from 1 to 10 by 1.
- Modify the program to count from 5 to 10 by 1.
- Modify the program to count from 0 to 10 by 2.
- Trade places, so that both partners have an opportunity to "drive" the visual programming environment.
- Modify the program to count from any start value the user enters to 10 by 1.
- Modify the program to count from any start value the user enters to any stop value the user enters by 1.
- Modify the program to count from any start value the user enters to any stop value the user enters by any increment value the user enters.
- Change the environment to use a slow run speed and/or step through the program one shape at a time.
- Working together, create a list of changes that might be made to use while loops in programs you've already written. What parts could be repeated and how would the loop terminate?
Applications[edit | edit source]
- Identify specific steps which must be followed when creating a program using while loops.
- 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?