Android™ How to Program, Second Edition

C.9. Case Study: Sentinel-Controlled Repetition

Let’s generalize Section C.8’s class-average problem. Consider the following problem:

Develop a class-averaging program that processes grades for an arbitrary number of students each time it’s run.

In the previous class-average example, the problem statement specified the number of students, so the number of grades (10) was known in advance. In this example, no indication is given of how many grades the user will enter during the program’s execution. The program must process an arbitrary number of grades. How can it determine when to stop reading grades from the user? How will it know when to calculate and print the class average?

One way to solve this problem is to use a special value called a ...