Array access

Learn to access array elements by index.

Array access

Array elements are accessed by index: array[0] gives the first element. Indices start at 0.

val fruits = arrayOf("apple", "pear", "cherry")
println(fruits[0])  // apple
println(fruits[2])  // cherry

fruits[0] is the first element ("apple"), fruits[2] the third ("cherry"). Since indices start at 0, the last index of an N-element array is N-1.

Going beyond the bounds throws IndexOutOfBoundsException.

Index bounds and mutation

Array elements can be both read and written with arr[index] (if declared with var).

val nums = intArrayOf(3, 7, 2)
println(nums[1])  // 7
nums[1] = 9
println(nums[1])  // 9

Here nums[1] first gave 7; then nums[1] = 9 changed it to 9. Even with val nums, elements can be changed; only the array itself cannot be reassigned.

Index starts at 0 and goes up to size - 1.

Exercise Print the first and last element

Write a fun main(). Create an array with val fruits = arrayOf("apple", "pear", "cherry"). Print the first element with println(fruits[0]) and the last with println(fruits[2]).

Show example solution

fun main() {
    val fruits = arrayOf("apple", "pear", "cherry")
    println(fruits[0])
    println(fruits[2])
}

Test yourself

Match the indices

arr[0]

First element
arr[1]

Second element
arr[N-1]

Last element
arr[N]

Error (out of bounds)
val arr = arrayOf("a", "b", "c") — what does arr[0] return?
- "a"
- Error
- "b"
- "c"
Show answer

"a" — arr[0] gives "a", the first element.
Complete the first element access
```
println(fruits[____])
```
Show answer
```
println(fruits[0])
```

Next lesson: Array size

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