PHP Arrays

An array stores multiple values in one single variable:

Example

$cars = array("Volvo", "BMW", "Toyota");

What is an Array?

An array is a special variable that can hold many values under a single name, and you can access the values by referring to an index number or name.

PHP Array Types

In PHP, there are three types of arrays:

Indexed arrays - Arrays with a numeric index
Associative arrays - Arrays with named keys
Multidimensional arrays - Arrays containing one or more arrays

Working With Arrays

In this tutorial you will learn how to work with arrays, including:

Create Arrays
Access Arrays
Update Arrays
Add Array Items
Remove Array Items
Sort Arrays

Array Items

Array items can be of any data type.

The most common are strings and numbers (int, float), but array items can also be objects, functions or even arrays.

You can have different data types in the same array.

Example

Array items of four different data types:

$myArr = array("Volvo", 15, ["apples", "bananas"], myFunction);

Array Functions

The real strength of PHP arrays are the built-in array functions, like the count() function for counting array items:

Example

How many items are in the $cars array:

$cars = array("Volvo", "BMW", "Toyota");
echo count($cars);

Indexed Arrays

PHP Indexed Arrays

In indexed arrays each item has an index number.

By default, the first item has index 0, the second item has item 1, etc.

Example

Create and display an indexed array:

$cars = array("Volvo", "BMW", "Toyota");
var_dump($cars);

Access Indexed Arrays

To access an array item you can refer to the index number.

Example

Display the first array item:

$cars = array("Volvo", "BMW", "Toyota");
echo $cars[0];

Change Value

To change the value of an array item, use the index number:

Example

Change the value of the second item:

$cars = array("Volvo", "BMW", "Toyota");
$cars[1] = "Ford";
var_dump($cars);

Loop Through an Indexed Array

To loop through and print all the values of an indexed array, you could use a foreach loop, like this:

Example

Display all array items:

$cars = array("Volvo", "BMW", "Toyota");
foreach ($cars as $x) {
  echo "$x <br>";
}

Index Number

The key of an indexed array is a number, by default the first item is 0 and the second is 1 etc., but there are exceptions.

New items get the next index number, meaning one higher than the highest existing index.

So if you have an array like this:

$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";

And if you use the array_push() function to add a new item, the new item will get the index 3:

Example

array_push($cars, "Ford");
var_dump($cars);

But if you have an array with random index numbers, like this:

$cars[5] = "Volvo";
$cars[7] = "BMW";
$cars[14] = "Toyota";

And if you use the array_push() function to add a new item, what will be the index number of the new item?

Example

array_push($cars, "Ford");
var_dump($cars);

Associative Arrays

PHP Associative Arrays

Associative arrays are arrays that use named keys that you assign to them.

Example

$car = array("brand"=>"Ford", "model"=>"Mustang", "year"=>1964);
var_dump($car);

Access Associative Arrays

To access an array item you can refer to the key name.

Example

Display the model of the car:

$car = array("brand"=>"Ford", "model"=>"Mustang", "year"=>1964);
echo $car["model"];

Change Value

To change the value of an array item, use the key name:

Example

Change the year item:

$car = array("brand"=>"Ford", "model"=>"Mustang", "year"=>1964);
$car["year"] = 2024;
var_dump($car);

Loop Through an Associative Array

To loop through and print all the values of an associative array, you could use a foreach loop, like this:Example

Display all array items, keys and values:

$car = array("brand"=>"Ford", "model"=>"Mustang", "year"=>1964);

foreach ($car as $x => $y) {
  echo "$x: $y <br>";
}

Create Array

You can create arrays by using the array() function:

Example

$cars = array("Volvo", "BMW", "Toyota");

You can also use a shorter syntax by using the [] brackets:

Example

$cars = ["Volvo", "BMW", "Toyota"];

Multiple Lines

Line breaks are not important, so an array declaration can span multiple lines:

Example

$cars = [
  "Volvo",
  "BMW",
  "Toyota"
];

Trailing Comma

A comma after the last item is allowed:

Example

$cars = [
  "Volvo",
  "BMW",
  "Toyota",
];

Array Keys

When creating indexed arrays the keys are given automatically, starting at 0 and increased by 1 for each item, so the array above could also be created with keys:

Example

$cars = [
  0 => "Volvo",
  1 => "BMW",
  2 =>"Toyota"
];

As you can see, indexed arrays are the same as associative arrays, but associative arrays have names instead of numbers:

Example

$myCar = [
  "brand" => "Ford",
  "model" => "Mustang",
  "year" => 1964
];

Declare Empty Array

You can declare an empty array first, and add items to it later:

Example

$cars = [];
$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";

The same goes for associative arrays, you can declare the array first, and then add items to it:

Example

$myCar = [];
$myCar["brand"] = "Ford";
$myCar["model"] = "Mustang";
$myCar["year"] = 1964;

Mixing Array Keys

You can have arrays with both indexed and named keys:

Example

$myArr = [];
$myArr[0] = "apples";
$myArr[1] = "bananas";
$myArr["fruit"] = "cherries";

Access Array Item

To access an array item, you can refer to the index number for indexed arrays, and the key name for associative arrays.

Example

Access an item by referring to its index number:

$cars = array("Volvo", "BMW", "Toyota");
echo $cars[2];

Note: The first item has index 0.

To access items from an associative array, use the key name:

Example

Access an item by referring to its key name:

$cars = array("brand" => "Ford", "model" => "Mustang", "year" => 1964);
echo $cars["year"];

Double or Single Quotes

You can use both double and single quotes when accessing an array:

Example

echo $cars["model"];
echo $cars['model'];

Excecute a Function Item

Array items can be of any data type, including function.

To execute such a function, use the index number followed by parentheses ():

Example

Execute a function item:

function myFunction() {
  echo "I come from a function!";
}

$myArr = array("Volvo", 15, myFunction);

$myArr[2]();

Use the key name when the function is an item in a associative array:

Example

Execute function by referring to the key name:

function myFunction() {
  echo "I come from a function!";
}

$myArr = array("car" => "Volvo", "age" => 15, "message" => myFunction);

$myArr["message"]();

Loop Through an Associative Array

To loop through and print all the values of an associative array, you can use a foreach loop, like this:

Example

Display all array items, keys and values:

$car = array("brand"=>"Ford", "model"=>"Mustang", "year"=>1964);

foreach ($car as $x => $y) {
  echo "$x: $y <br>";
}

Loop Through an Indexed Array

To loop through and print all the values of an indexed array, you can use a foreach loop, like this:

Example

Display all array items:

$cars = array("Volvo", "BMW", "Toyota");
foreach ($cars as $x) {
  echo "$x <br>";
}

Update Array Item

To update an existing array item, you can refer to the index number for indexed arrays, and the key name for associative arrays.

Example

Change the second array item from "BMW" to "Ford":

$cars = array("Volvo", "BMW", "Toyota");
$cars[1] = "Ford";

Note: The first item has index 0.

To update items from an associative array, use the key name:

Example

Update the year to 2024:

$cars = array("brand" => "Ford", "model" => "Mustang", "year" => 1964);
$cars["year"] = 2024;

Update Array Items in a Foreach Loop

There are different techniques to use when changing item values in a foreach loop.

One way is to insert the & character in the assignment to assign the item value by reference, and thereby making sure that any changes done with the array item inside the loop will be done to the original array:

Example

Change ALL item values to "Ford":

$cars = array("Volvo", "BMW", "Toyota");
foreach ($cars as &$x) {
  $x = "Ford";
}
unset($x);
var_dump($cars);

Note: Remember to add the unset() function after the loop.

Without the unset($x) function, the $x variable will remain as a reference to the last array item.

To demonstrate this, see what happens when we change the value of $x after the foreach loop:

Example

Demonstrate the consequence of forgetting the unset() function:

$cars = array("Volvo", "BMW", "Toyota");
foreach ($cars as &$x) {
  $x = "Ford";
}

$x = "ice cream";

var_dump($cars);

Add Array Item

To add items to an existing array, you can use the bracket [] syntax.

Example

Add one more item to the fruits array:

$fruits = array("Apple", "Banana", "Cherry");
$fruits[] = "Orange";

Associative Arrays

To add items to an associative array, or key/value array, use brackets [] for the key, and assign value with the = operator.

Example

Add one item to the car array:

$cars = array("brand" => "Ford", "model" => "Mustang");
$cars["color"] = "Red";

Add Multiple Array Items

To add multiple items to an existing array, use the array_push() function.

Example

Add three item to the fruits array:

$fruits = array("Apple", "Banana", "Cherry");
array_push($fruits, "Orange", "Kiwi", "Lemon");

Add Multiple Items to Associative Arrays

To add multiple items to an existing array, you can use the += operator.

Example

Add two items to the cars array:

$cars = array("brand" => "Ford", "model" => "Mustang");
$cars += ["color" => "red", "year" => 1964];

Remove Array Item

To remove an existing item from an array, you can use the array_splice() function.

With the array_splice() function you specify the index (where to start) and how many items you want to delete.

Example

Remove the second item:

$cars = array("Volvo", "BMW", "Toyota");
array_splice($cars, 1, 1);

After the deletion, the array gets reindexed automatically, starting at index 0.

Using the unset Function

You can also use the unset() function to delete existing array items.

Note: The unset() function does not re-arrange the indexes, meaning that after deletion the array will no longer contain the missing indexes.

Example

Remove the second item:

$cars = array("Volvo", "BMW", "Toyota");
unset($cars[1]);

Remove Multiple Array Items

To remove multiple items, the array_splice() function takes a length parameter that allows you to specify the number of items to delete.

Example

Remove 2 items, starting a the second item (index 1):

$cars = array("Volvo", "BMW", "Toyota");
array_splice($cars, 1, 2);

The unset() function takes a unlimited number of arguments, and can therefore be used to delete multiple array items:

Example

Remove the first and the second item:

$cars = array("Volvo", "BMW", "Toyota");
unset($cars[0], $cars[1]);

Remove Item From an Associative Array

To remove items from an associative array, you can use the unset() function.

Specify the key of the item you want to delete.

Example

Remove the "model":

$cars = array("brand" => "Ford", "model" => "Mustang", "year" => 1964);
unset($cars["model"]);

Using the array_diff Function

You can also use the array_diff() function to remove items from an associative array.

This function returns a new array, without the specified items.

Example

Create a new array, without "Mustang" and "1964":

$cars = array("brand" => "Ford", "model" => "Mustang", "year" => 1964);
$newarray = array_diff($cars, ["Mustang", 1964]);

Note: The array_diff() function takes values as parameters, and not keys.

Remove the Last Item

The array_pop() function removes the last item of an array.

Example

Remove the last item:

$cars = array("Volvo", "BMW", "Toyota");
array_pop($cars);

Remove the First Item

The array_shift() function removes the first item of an array.

Example

Remove the first item:

$cars = array("Volvo", "BMW", "Toyota");
array_shift($cars);

Sorting Arrays

The elements in an array can be sorted in alphabetical or numerical order, descending or ascending.

PHP - Sort Functions For Arrays

In this chapter, we will go through the following PHP array sort functions:

sort() - sort arrays in ascending order
rsort() - sort arrays in descending order
asort() - sort associative arrays in ascending order, according to the value
ksort() - sort associative arrays in ascending order, according to the key
arsort() - sort associative arrays in descending order, according to the value
krsort() - sort associative arrays in descending order, according to the key

Sort Array in Ascending Order - sort()

The following example sorts the elements of the $cars array in ascending alphabetical order:

Example

$cars = array("Volvo", "BMW", "Toyota");
sort($cars);

The following example sorts the elements of the $numbers array in ascending numerical order:

Example

$numbers = array(4, 6, 2, 22, 11);
sort($numbers);

Sort Array in Descending Order - rsort()

The following example sorts the elements of the $cars array in descending alphabetical order:

Example

$cars = array("Volvo", "BMW", "Toyota");
rsort($cars);

The following example sorts the elements of the $numbers array in descending numerical order:

Example

$numbers = array(4, 6, 2, 22, 11);
rsort($numbers);

Sort Array (Ascending Order), According to Value - asort()

The following example sorts an associative array in ascending order, according to the value:

Example

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
asort($age);

Sort Array (Ascending Order), According to Key - ksort()

The following example sorts an associative array in ascending order, according to the key:

Example

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
ksort($age);

Sort Array (Descending Order), According to Value - arsort()

The following example sorts an associative array in descending order, according to the value:

Example

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
arsort($age);

Sort Array (Descending Order), According to Key - krsort()

The following example sorts an associative array in descending order, according to the key:

Example

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
krsort($age);

Multidimensional Arrays

So far we have described arrays that are a single list of key/value pairs.

However, sometimes you want to store values with more than one key. For this, we have multidimensional arrays.

A multidimensional array is an array containing one or more arrays.

PHP supports multidimensional arrays that are two, three, four, five, or more levels deep. However, arrays more than three levels deep are hard to manage for most people.

The dimension of an array indicates the number of indices you need to select an element.

For a two-dimensional array you need two indices to select an element
For a three-dimensional array you need three indices to select an element

PHP - Two-dimensional Arrays

A two-dimensional array is an array of arrays (a three-dimensional array is an array of arrays of arrays).

First, take a look at the following table:

Name	Stock	Sold
Volvo	22	18
BMW	15	13
Saab	5	2
Land Rover	17	15

We can store the data from the table above in a two-dimensional array, like this:

$cars = array (
  array("Volvo",22,18),
  array("BMW",15,13),
  array("Saab",5,2),
  array("Land Rover",17,15)
);

Now the two-dimensional $cars array contains four arrays, and it has two indices: row and column.

To get access to the elements of the $cars array we must point to the two indices (row and column):

Example

echo $cars[0][0].": In stock: ".$cars[0][1].", sold: ".$cars[0][2].".<br>";
echo $cars[1][0].": In stock: ".$cars[1][1].", sold: ".$cars[1][2].".<br>";
echo $cars[2][0].": In stock: ".$cars[2][1].", sold: ".$cars[2][2].".<br>";
echo $cars[3][0].": In stock: ".$cars[3][1].", sold: ".$cars[3][2].".<br>";

We can also put a for loop inside another for loop to get the elements of the $cars array (we still have to point to the two indices):

Example

for ($row = 0; $row < 4; $row++) {
  echo "<p><b>Row number $row</b></p>";
  echo "<ul>";
    for ($col = 0; $col < 3; $col++) {
      echo "<li>".$cars[$row][$col]."</li>";
    }
  echo "</ul>";
}

Array Functions

PHP has a set of built-in functions that you can use on arrays.

Function	Description
array()	Creates an array
array_change_key_case()	Changes all keys in an array to lowercase or uppercase
array_chunk()	Splits an array into chunks of arrays
array_column()	Returns the values from a single column in the input array
array_combine()	Creates an array by using the elements from one "keys" array and one "values" array
array_count_values()	Counts all the values of an array
array_diff()	Compare arrays, and returns the differences (compare values only)
array_diff_assoc()	Compare arrays, and returns the differences (compare keys and values)
array_diff_key()	Compare arrays, and returns the differences (compare keys only)
array_diff_uassoc()	Compare arrays, and returns the differences (compare keys and values, using a user-defined key comparison function)
array_diff_ukey()	Compare arrays, and returns the differences (compare keys only, using a user-defined key comparison function)
array_fill()	Fills an array with values
array_fill_keys()	Fills an array with values, specifying keys
array_filter()	Filters the values of an array using a callback function
array_flip()	Flips/Exchanges all keys with their associated values in an array
array_intersect()	Compare arrays, and returns the matches (compare values only)
array_intersect_assoc()	Compare arrays and returns the matches (compare keys and values)
array_intersect_key()	Compare arrays, and returns the matches (compare keys only)
array_intersect_uassoc()	Compare arrays, and returns the matches (compare keys and values, using a user-defined key comparison function)
array_intersect_ukey()	Compare arrays, and returns the matches (compare keys only, using a user-defined key comparison function)
array_key_exists()	Checks if the specified key exists in the array
array_keys()	Returns all the keys of an array
array_map()	Sends each value of an array to a user-made function, which returns new values
array_merge()	Merges one or more arrays into one array
array_merge_recursive()	Merges one or more arrays into one array recursively
array_multisort()	Sorts multiple or multi-dimensional arrays
array_pad()	Inserts a specified number of items, with a specified value, to an array
array_pop()	Deletes the last element of an array
array_product()	Calculates the product of the values in an array
array_push()	Inserts one or more elements to the end of an array
array_rand()	Returns one or more random keys from an array
array_reduce()	Returns an array as a string, using a user-defined function
array_replace()	Replaces the values of the first array with the values from following arrays
array_replace_recursive()	Replaces the values of the first array with the values from following arrays recursively
array_reverse()	Returns an array in the reverse order
array_search()	Searches an array for a given value and returns the key
array_shift()	Removes the first element from an array, and returns the value of the removed element
array_slice()	Returns selected parts of an array
array_splice()	Removes and replaces specified elements of an array
array_sum()	Returns the sum of the values in an array
array_udiff()	Compare arrays, and returns the differences (compare values only, using a user-defined key comparison function)
array_udiff_assoc()	Compare arrays, and returns the differences (compare keys and values, using a built-in function to compare the keys and a user-defined function to compare the values)
array_udiff_uassoc()	Compare arrays, and returns the differences (compare keys and values, using two user-defined key comparison functions)
array_uintersect()	Compare arrays, and returns the matches (compare values only, using a user-defined key comparison function)
array_uintersect_assoc()	Compare arrays, and returns the matches (compare keys and values, using a built-in function to compare the keys and a user-defined function to compare the values)
array_uintersect_uassoc()	Compare arrays, and returns the matches (compare keys and values, using two user-defined key comparison functions)
array_unique()	Removes duplicate values from an array
array_unshift()	Adds one or more elements to the beginning of an array
array_values()	Returns all the values of an array
array_walk()	Applies a user function to every member of an array
array_walk_recursive()	Applies a user function recursively to every member of an array
arsort()	Sorts an associative array in descending order, according to the value
asort()	Sorts an associative array in ascending order, according to the value
compact()	Create array containing variables and their values
count()	Returns the number of elements in an array
current()	Returns the current element in an array
each()	Deprecated from PHP 7.2. Returns the current key and value pair from an array
end()	Sets the internal pointer of an array to its last element
extract()	Imports variables into the current symbol table from an array
in_array()	Checks if a specified value exists in an array
key()	Fetches a key from an array
krsort()	Sorts an associative array in descending order, according to the key
ksort()	Sorts an associative array in ascending order, according to the key
list()	Assigns variables as if they were an array
natcasesort()	Sorts an array using a case insensitive "natural order" algorithm
natsort()	Sorts an array using a "natural order" algorithm
next()	Advance the internal array pointer of an array
pos()	Alias of current()
prev()	Rewinds the internal array pointer
range()	Creates an array containing a range of elements
reset()	Sets the internal pointer of an array to its first element
rsort()	Sorts an indexed array in descending order
shuffle()	Shuffles an array
sizeof()	Alias of count()
sort()	Sorts an indexed array in ascending order
uasort()	Sorts an array by values using a user-defined comparison function and maintains the index association
uksort()	Sorts an array by keys using a user-defined comparison function
usort()	Sorts an array by values using a user-defined comparison function

PHP Tutorial

PHP Arrays

Example

What is an Array?

PHP Array Types

Working With Arrays

Array Items

Example

Array Functions

Example

Indexed Arrays

PHP Indexed Arrays

Example

Access Indexed Arrays

Example

Change Value

Example

Loop Through an Indexed Array

Example

Index Number

Example

Example

Associative Arrays

PHP Associative Arrays

Example

Access Associative Arrays

Example

Change Value

Example

Loop Through an Associative Array

Create Array

Example

Example

Multiple Lines

Example

Trailing Comma

Example

Array Keys

Example

Example

Declare Empty Array

Example

Example

Mixing Array Keys

Example

Access Array Item

Example

Example

Double or Single Quotes

Example

Excecute a Function Item

Example

Example

Loop Through an Associative Array

Example

Loop Through an Indexed Array

Example

Update Array Item

Example

Example

Update Array Items in a Foreach Loop

Example

Example

Add Array Item

Example

Associative Arrays

Example

Add Multiple Array Items

Example

Add Multiple Items to Associative Arrays

Example

Remove Array Item

Example

Using the unset Function

Example

Remove Multiple Array Items

Example

Example

Remove Item From an Associative Array

Example