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App Inventor
book

App Inventor

by David Wolber, Hal Abelson, Ellen Spertus, Liz Looney
May 2011
Beginner to intermediate content levelBeginner to intermediate
386 pages
11h 41m
English
O'Reilly Media, Inc.
Content preview from App Inventor

Chapter 18. Programming Your App to Make Decisions: Conditional Blocks

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Computers, even small ones like the phone in your pocket, are good at performing thousands of operations in just a few seconds. Even more impressively, they can also make decisions based on the data in their memory banks and logic specified by the programmer. This decision-making capability is probably the key ingredient of what people think of as artificial intelligence—and it’s definitely a very important part of creating smart, interesting apps! In this chapter, we’ll explore how to build decision-making logic into your apps.

As we discussed in Chapter 14, an app’s behavior is defined by a set of event handlers. Each event handler executes specific functions in response to a particular event. The response need not be a linear sequence of functions, however; you can specify that some functions be performed only under certain conditions. A game app might check if the score has reached 100. A location-aware app might ask if the phone is within the boundaries of some building. Your app can ask such questions and, depending on the answer, proceed down a certain program branch (or direction).

Figure 18-1 depicts a flowchart of an event handler with a conditional check.

An event handler that tests for a condition and branches accordingly

Figure 18-1. An event handler that tests for a condition ...

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Publisher Resources

ISBN: 9781449306786Supplemental ContentErrata Page