Arrays: Working with lists of objects

Unit IV: Advanced Techniques

An array is a list. When you declare a variable in Alice, you can select to make it an array.

In this lesson, you will declare and use arrays. An array is a variable that is a list.
You will create arrays of words, numbers, or objects, then use loops to process the entire array.

An array is a list. When you declare an array in Alice, you can select to make it an array.

The variable greeting is not an array, it is a scalar. It has a single value, “Hello World”. When the tortoise says greeting, he says “Hello World”

The variable sayings is an array. The items in an array are numbered starting with 0. The number is called the index or subscript. When you use an array you need to use a subscript to specify which item, or element, in the list is to be used.

In this example, the tortoise says sayings[0], of “Ready”.

An array can also use variables as the subscript:

In this example, num is 1, so when the tortoise says sayings[num] he says “Set”.

In this module, you will declare and use arrays. An array is a variable that is a list.
You will create arrays of words, numbers, or objects, then use loops to process the entire array.

In this chapter, you will learn how to declare and use arrays, (lists) to organize and work with groups of data and objects. You will explore how lists can be used to perform actions on groups of objects and learn to create lists containing different types of data, including 3D objects. You will also use control structures designed to operate on lists and examine how parallel lists can store related information. Finally, you will learn how to use lists of segments to organize and control parts of an animation.

Objectives:

• Declare a variable to be an array;
• Create code to assign initial values to an array;
• Use subscripts or index to access the elements of the array;
• Utilize loop control structures to process all of the elements of the array;
• Create and process arrays of different data types, including arrays of objects;
• Understand the purpose of parallel arrays and ways to use them;
• Experiment with arrays of segments.

Please study the material at each of the links below.

1. Arrays: Ready, Set, Go!: Tortoise says "Ready", "Set", "Go" using array
2. An array of animals: An array of SJointedModel contains, yeti, tortoise and stuffedTiger
3. The animals talk: Parallel Arrays: One array contains animals, the other the things they say
4. Who's the tallest?: People are in an array, a loop is used to find the tallest.
5. Animals counting: An array of animals take turns to count
6. Birds spread wings and say something: An array of birds perform
7. Fish swim to cave with procedure: Each fish swims to cave with procedure
8. Array of Objects: An array is madeup of different classes
9. Segments of an elephant's trunk as an array: The segments of an elephant's trunk, tail and a few other things are an array.
10. Self-Study Questions: What have you learned?
11. Active Learning: Arrays: Show what have you learned
12. Complete Step 6: Scene Procedures for the final project.
13. Discussion questions: What do you think?

Glossary for Arrays: Working with lists of objects
Full Glossary