# Chapter 46 - Arrays

Slide 1: Describe a good reason to use arrays.

Slide 2: What is an array?
What is a cell?
What is an index?

Facts:

• The cells are numbered sequentially starting at ________.
• If there are N cells in an array, the indexes will be _____ through _______.

What is another name for an index?

Which thing can change in an array: the number of cells or the elements?

What is in data[7]? ______

Show how the array changes after this line of code:

`data[3] = 99 ; `

What is the value of the arithmetic expression:

`data[2] + data[6]? ________`

On your own: what is the value of data[4]+data[8]? _______
A tricky one: Make your best guess: what is data[data[6]]? __________
Show what happens in the array as a result of executing the statement:

```data[0] = data[6] + 8;
```

Is an array an object?________

This is different than the example in the chapter:

`Given this code:double[] data = new double[5];  `
1. What is the length of the array data?
2. What are the indexes of data?

### Bounds Checking:

1. Can an index be negative? ____
2. Can an index have a decimal part like 2.75? ______
3. Can an index be 0? _______
4. What is the error that happens if you try to reference an index that doesn't exist? ______________________________

### Array Initialization

Each cell of a numeric array is initialized to _____________. Each cell of an array of object references is initialized to _______________

.