Learn

Data Structures

Access by Index

Here’s something interesting about arrays: each element in the array has what’s called an *index*. The first element is at index `0`

, the next is at index `1`

, the following is at index `2`

, and so on. We can access elements of the array directly through these numbers using brackets, like so:

```
array = [5, 7, 9, 2, 0]
array[2]
# returns "9", since "9"
# is at index 2
```

The diagram below shows how these indices work for our sample array, `[5, 7, 9, 2, 0]`

. The first element has index `0`

, the next has `1`

, the next has `2`

, and so on.

```
+---+---+---+---+---+
array | 5 | 7 | 9 | 2 | 0 |
+---+---+---+---+---+
index 0 1 2 3 4
```

(This is a bit of an oversimplification, but it gets the idea across for now).

We can access the `i`

th element of an array called `array`

by putting the index in square brackets, like so: `array[i]`

. `array[0]`

gets the first element, `array[1]`

gets the second element, and so on. This is called *access by index*.

Use square bracket notation to `print`

the third value of `demo_array`

to the console.

Remember that the third value is at index `2`

, not at index `3`

. We start counting indices from zero.