PHP Array

Summary: in this tutorial, you’ll learn about PHP arrays and how to manipulate array elements effectively.

Introduction to PHP arrays #

By definition, an array is a list of elements. For example, you may have an array that contains a list of products.

PHP provides you with two types of arrays:

• Indexed arrays
• Associative arrays

The keys of the indexed array are integers that start at 0. Typically, you use indexed arrays to access the elements by their positions.

The keys of an associative array are strings. You use associative arrays when you want to access elements by string keys.

This tutorial focuses on the indexed array.

Creating arrays #

In PHP, you can use the array() construct or [] syntax to define an array. The [] syntax is shorter and more convenient.

Creating an array using the array() construct #

To define an array, you use the array() construct. The following example creates an empty array:

<?php

$empty_array = array();Code language: HTML, XML (xml)

To create an array with some initial elements, you place a comma-separated list of elements within parentheses of the array() construct.

For example, the following defines an array that has three numbers:

<?php

$scores = array(1, 2, 3);Code language: HTML, XML (xml)

Creating an array using the [] syntax #

PHP provides a more convenient way to define arrays with the shorter syntax [], known as JSON notation.

The following example uses [] syntax to create a new empty array:

<?php

$empty_array = [];Code language: HTML, XML (xml)

The following example uses the [] syntax to create a new array that consists of three numbers:

<?php

$scores = [1, 2, 3];Code language: HTML, XML (xml)

Displaying arrays #

To show the contents of an array, you use the var_dump() function. For example:

<?php

$scores = [1, 2, 3];
var_dump($scores);Code language: HTML, XML (xml)

Try it

Output:

array(3) {
  [0]=> int(1)
  [1]=> int(2)
  [2]=> int(3)
}Code language: PHP (php)

Or you can use the print_r() function:

<?php

$scores = array(1, 2, 3);
print_r($scores);Code language: HTML, XML (xml)

Try it

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)Code language: PHP (php)

To make the output more readable, you can wrap the output of the print_r() function inside a <pre> tag. For example:

<?php

$scores = [1, 2, 3];

echo '<pre>';
print_r($scores);
echo '</pre>';Code language: HTML, XML (xml)

Try it

Output:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)Code language: PHP (php)

It’s more convenient to define a function that prints out an array like this:

<?php

function print_array($data)
{
	echo '<pre>';
	print_r($data);
	echo '</pre>';
}

$scores = [1, 2, 3];

print_array($scores);Code language: HTML, XML (xml)

Try it

Output:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)Code language: PHP (php)

And then you can reuse the function whenever you want to display an array.

Accessing array elements #

To access an element in an array, you specify the index of the element within the square brackets:

$array_name[index]Code language: PHP (php)

Note that the index of the first element of an array begins with zero, not one.

The following example shows how to access the first element of the array:

<?php

$scores = [1, 2, 3];
echo $scores[0];Code language: HTML, XML (xml)

Try it

Output:

1

Adding an element to the array #

To add an element to an array, you use the following syntax:

$array_name[] = new_element;Code language: PHP (php)

PHP will calculate the highest numerical index plus one each time you assign an element to the array.

The following example shows how to add the number 4 to the $scores array:

<?php

$scores = [1, 2, 3];
$scores[] = 4;

print_r($scores);Code language: HTML, XML (xml)

Try it

In this example, we defined an array that consists of three numbers initially. Then, we added the number 4 to the array.

It’s possible to use an index when you add a new element to the array. For example:

$scores = [1, 2, 3];
$scores[3] = 4;Code language: PHP (php)

However, to do this, you must manually calculate the new index, which is not practical. Also, the value will be overwritten if the index is already used.

Changing array elements #

The following statement changes the element located at the index to the $new_element:

$array_name[index] = $new_element;Code language: PHP (php)

For example, to change the first element of the $scores array from 1 to zero, you do it as follows:

<?php

$scores = [1, 2, 3];
$scores[0] = 0;

print_r($scores);Code language: HTML, XML (xml)

Try it

Removing array elements #

To remove an element from an array, you use the unset() function. The following removes the second element of the $scores array:

<?php

$scores = [1, 2, 3];
unset($scores[1]);

print_r($scores);Code language: HTML, XML (xml)

Try it

Getting the size of an array #

To get the number of elements in an array, you use the count() function. For example:

<?php

$scores = [1, 2, 3, 4, 5];

echo count($scores);Code language: HTML, XML (xml)

Try it

Output:

5

Summary #

• Use the array() construct or [] syntax to create a new array.
• For the indexed array, the first index begins with zero.
• To access an array element, use an index in the square bracket $array_name[index].
• Use the count() function to get the number of elements in an array.