Arrays

Array stores multiple values.

Initialization

There are couple of ways to initialize array:

Empty array

$arrayName = [];

Initial values

$colors = ["red", "green", "blue"];

In this example an array with 3 elements is created.

Size

Size is the count of elements in array.

It's accessed via the count function.

$prices = [15, 20, 30]; echo count($prices);

Output:

3

Accessing values

Array's values can be accessed via indexes starting from 0.

If we declare the following array:

$scores = [ 60, 78, 95, 88 ];

It's elements are:

So if we type the following line:

echo $scores[0] . ' ' . $scores[1];

It will print:

60 78

Index out of Bounds

Accessing index outside of the array results in warning and returns value of null.

Let's have an array with 4 elements. If we access the 4th or higher index null will be returned.

Such example is:

$scores = [ 60, 78, 95, 88 ]; if($scores[4] === null) { echo 'NOT SET'; }

Output:

Notice: Undefined offset: 4 in index.php on line 4 NOT SET

Printing All Elements

Let's have an example in which all elements of array are printed.

<?php $scores = [60, 78, 95, 88]; foreach($scores as $score) { echo $score . " "; }

Output:

60 78 95 88

foreach loop is convenient but for loop could be used too.

Inserting Elements

Elements can be inserted using [] or the array_push function.

Let's have a program which fills array with values:

<?php $ages = []; // Elements insertion $ages[] = 15; $ages[] = 25; // Alternative way for element's insertion: array_push($ages, 28);

Product Of Elements

Let's have a program which calculates the product of all even numbers:

<?php $numbers = [2,3,4,5]; $multiplication = 1; foreach($numbers as $num) { if($num % 2 === 0) { // If number is even. $multiplication *= $num; } } echo $multiplication;

Output:

8

The only even numbers in the array are 2 and 4 which are multiplied.