Lists
A List is a variable that can hold multiple values.
Each item, or element, is separated by a comma.
// A list of strings $letters = ['a', 'b', 'c']; // A list of numbers $evenNumbers = [2, 4, 6, 8, 10]; // Multi-line format $countries = [ 'Argentina', 'Brazil', 'Chile' ]; // Each item can be an expression $nums = [1 + 9, 2 + 8];
JargonIn other languages, Lists are often called Arrays.
List Elements
You can access elements of a list by the index number of its position.
THT lists use zero-based indexes: the first element is 0
, the second element is 1
, etc.
$letters = ['a', 'b', 'c', 'd']; $first = $letters[0]; //= 'a' $second = $letters[1]; //= 'b' // Negative indexes start counting from the end $last = $letters[-1]; //= 'd' $nextToLast = $letters[-2]; //= 'c' // Modify an index directly $letters[0] = 'x'; print($letters); //= ['x', 'b', 'c', 'd']
List Methods
Here are some common List methods.
$colors = ['red', 'blue']; $colors.contains('blue'); //= true $colors.length(); //= 2 $colors.join(' & '); //= 'red & blue'
The methods push
and pop
treat the List as a stack of items.
They add and remove the last item in the List.
(Tip: Think of a spring-loaded stack of plates in a cafeteria.)
$colors = ['red', 'blue']; // Add an item to the end $colors.push('yellow'); //= ['red', 'blue', 'yellow'] // Remove item from the end and return it $colors.pop(); //= 'yellow' print($colors); //= ['red', 'blue']
The methods insert
and remove
let you add and delete
items anywhere in the List.
$colors = ['red', 'blue']; // Add item to the 2nd slot (index: 1) $colors.insert('orange', 1); //= ['red', 'orange', 'blue'] // Remove item from beginning (index: 0) $colors.remove(0); //= 'red' print($colors); //= ['orange', 'blue']