In this chapter, you will learn how to create more complex code by adding conditions, selections, and loop structures. We will also show you how to do error handling in Red. This is illustrated throughout the chapter through the development of a guessing game, in which the user must guess a secret number between 1 and 99. That secret number is randomly generated in the program.

To do this, we need to learn how to get data into a Red program and how to test this input. We need to do this a number of times until the right number is guessed. Overall, we need to make sure our program can deal with the wrong kinds of input.

In this chapter, we will cover the following topics:

• Getting input from the user
• Testing conditions
• Structuring repetitions
• The number-guessing game
• Handling errors
• Creating and catching errors