Mastering PHP Arrays: A Comprehensive Guide
PHP arrays are one of the most powerful data structures in PHP, enabling developers to store, manipulate, and manage data efficiently. Whether you're dealing with simple lists or complex multidimensional arrays, understanding PHP's built-in array functions can significantly improve your coding productivity. In this guide, we will cover common PHP array manipulation functions and provide essential performance tips.
What is a PHP Array?
In PHP, an array is a data structure that stores multiple values under a single variable name. These values can be of any type—strings, integers, objects, or even other arrays. Arrays in PHP are dynamic, meaning they can grow or shrink as needed, and they support both indexed and associative keys.
Simple Arrays - Indexed Arrays
Indexed Arrays: Arrays with numeric keys.
A simple array is a linear collection of values, typically indexed numerically starting from 0. PHP supports two syntaxes: the traditional array() and the modern short syntax [].
Syntax
// Traditional syntax
$simpleArray1 = array("Apple", "Banana", "Orange");
// Short syntax (PHP 5.4+)
$simpleArray2 = ["Apple", "Banana", "Orange"];
Example
$fruits = ["Apple", "Banana", "Orange"];
// Accessing elements
echo $fruits[1]; // Output: Banana
// Update an element
$fruits[2] = "Mango";
Associative Array (Key-Value Pairs)
Associative arrays use named keys instead of numeric indices.
Syntax
$ages = [
"Alice" => 25,
"Bob" => 30,
"Charlie" => 35
];
echo $ages["Bob"]; // Output: 30
Nested Arrays (Multidimensional Arrays)
A nested array, or multidimensional array, is an array containing one or more arrays as its elements. This is useful for representing complex data structures like tables or matrices.
Syntax
$nestedArray = [
"fruits" => ["Apple", "Banana", "Orange"],
"vegetables" => ["Carrot", "Broccoli"]
];
Example
$students = [
"John" => [
"age" => 20,
"grades" => [85, 90, 88]
],
"Jane" => [
"age" => 22,
"grades" => [92, 87, 95]
]
];
// Accessing nested values
echo $students["John"]["grades"][1]; // Output: 90
<?php
$matrix = array(
array(1, 2, 3),
array(4, 5, 6),
array(7, 8, 9)
);
// Accessing elements
echo $matrix[0][1]; // Output: 2
echo $matrix[2][2]; // Output: 9
$users = [
[
'name' => 'John',
'orders' => [
['product' => 'Laptop', 'price' => 1200],
['product' => 'Mouse', 'price' => 25]
]
],
[
'name' => 'Jane',
'orders' => [
['product' => 'Keyboard', 'price' => 80]
]
]
];
echo $users[0]['orders'][0]['product']; //output: Laptop
?>
Creating an Array in PHP
$users = []; // Initialize an empty array
$fruits = ["Apple", "Banana", "Cherry"];
print_r($fruits);
// Create a nested array
$users = [
["name" => "Alice", "role" => "Developer"],
["name" => "Bob", "role" => "Designer"]
];
// Create an array with numbers from 0 to 99
$myArray = range(0, 99);
print_r($myArray); // Output: Array ( [0] => 0 [1] => 1 ... [99] => 99 )
Accessing Array Elements
$fruits = ["Apple", "Banana", "Cherry"];
echo $fruits[0]; // Output: Apple
Add Element to an Array
$array[] = value;: to add an element to the end of an array.array_push(): To add an element to the end of an array.$array['key'] = value;: To add an element to an associative array.array_unshift(): To add an element to the beginning of an array.array_splice(): To insert an element at a specific index.
<?php
$users = []; // Initialize an empty array
// Create: Add a new user
$users[] = ['name' => 'David', 'age' => 30];
array_push($users, ['name' => 'Sarah', 'age' => 25]);
print_r($users); // Output: Array ( [0] => Array ( [name] => David [age] => 30 ) [1] => Array ( [name] => Sarah [age] => 25 ) )
$fruits = ["Banana"];
$fruits[2] = "Apple"; // Add "Apple" at index 2
print_r($fruits); // Output: Array ( [0] => Banana [2] => Apple )
// add an element to the beginning of an array.
$fruits = ["Banana", "Orange"];
array_unshift($fruits, "Apple", "Mango");
print_r($fruits); // Output: Array ( [0] => Apple [1] => Mango [2] => Banana [3] => Orange )
// Insert at a Specific Index Using array_splice()
$numbers = [10, 20, 30, 40];
array_splice($numbers, 2, 0, 25); // Insert 25 at index 2
print_r($numbers); // [10, 20, 25, 30, 40]
Add multiple elements to an Array
array_merge(): To combine arrays.
$fruits = ["Apple", "Banana"];
$veggies = ["Carrot", "Broccoli"];
$combined = array_merge($fruits, $veggies);
print_r($combined); // Output: Array ( [0] => Apple [1] => Banana [2] => Carrot [3] => Broccoli )
Modifying Array Elements
$fruits = ["Apple", "Banana", "Cherry"];
$fruits[1] = "Mango"; // Replaces "Banana" with "Mango"
print_r($fruits);
Removing Array Elements
unset(): To remove an element by its key.array_splice(): To remove elements by their index.array_pop(): remove the last element.array_shift(): remove the first element.
$fruits = ["Apple", "Banana", "Cherry"];
unset($fruits[1]); // Removes "Banana"
print_r($fruits); // Output: Array ( [0] => Apple [2] => Cherry )
$numbers = [1,2,3,4,5];
array_splice($numbers, 2, 1); // remove the number 3.
print_r($numbers); // Output: Array ( [0] => 1 [1] => 2 [2] => 4 [3] => 5 )
$numbers = [1,2,3,4,5];
array_pop($numbers); // remove the last element.
print_r($numbers); // Output: Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 )
$numbers = [1,2,3,4,5];
array_shift($numbers); // remove the first element.
print_r($numbers); // Output: Array ( [0] => 2 [1] => 3 [2] => 4 [3] => 5 )
Copy an Array
$fruits = ["Apple", "Banana", "Cherry"];
$copy = $fruits; // Copy the array
$copy[0] = "Mango";
print_r($fruits); // Output: Array ( [0] => Apple [1] => Banana [2] => Cherry )
print_r($copy); // Output: Array ( [0] => Mango [1] => Banana [2] => Cherry )
Note: In PHP, arrays are copied by value by default. To copy an array by reference, use the & operator.
$fruits = ["Apple", "Banana", "Cherry"];
$copyByRef = &$fruits; // Copy by reference
$copyByRef[0] = "Mango";
print_r($fruits); // Output: Array ( [0] => Mango [1] => Banana [2] => Cherry )
print_r($copyByRef); // Output: Array ( [0] => Mango [1] => Banana [2] => Cherry )
Common PHP Array Manipulation Functions
PHP provides a rich set of built-in functions to manipulate arrays. Here are some of the most commonly used ones with examples:
count() - Get Array Length
$fruits = ["Apple", "Banana", "Orange"];
echo count($fruits); // Output: 3
in_array() - Check if a Value Exists
$fruits = ["Apple", "Banana", "Orange"];
if (in_array("Banana", $fruits)) {
echo "Found Banana!";
}
array_push() - Add Elements to the End
$fruits = ["Apple", "Banana"];
array_push($fruits, "Orange", "Mango");
print_r($fruits);
// Output: Array ( [0] => Apple [1] => Banana [2] => Orange [3] => Mango )
array_pop() - Remove the Last Element
$fruits = ["Apple", "Banana", "Orange"];
$lastFruit = array_pop($fruits);
echo $lastFruit; // Output: Orange
print_r($fruits); // Output: Array ( [0] => Apple [1] => Banana )
array_shift() - Remove the First Element
$fruits = ["Apple", "Banana", "Orange"];
$firstFruit = array_shift($fruits);
echo $firstFruit; // Output: Apple
print_r($fruits); // Output: Array ( [0] => Banana [1] => Orange )
array_unshift() - Add Elements to the Beginning
$fruits = ["Banana", "Orange"];
array_unshift($fruits, "Apple", "Mango");
print_r($fruits);
// Output: Array ( [0] => Apple [1] => Mango [2] => Banana [3] => Orange )
array_merge() - Combine Arrays
$fruits = ["Apple", "Banana"];
$veggies = ["Carrot", "Broccoli"];
$combined = array_merge($fruits, $veggies);
print_r($combined);
// Output: Array ( [0] => Apple [1] => Banana [2] => Carrot [3] => Broccoli )
array_keys() - Get Array Keys
$ages = ["Alice" => 25, "Bob" => 30];
$names = array_keys($ages);
print_r($names); // Output: Array ( [0] => Alice [1] => Bob )
array_values() - Get Array Values
$ages = ["Alice" => 25, "Bob" => 30];
$agesList = array_values($ages);
print_r($agesList); // Output: Array ( [0] => 25 [1] => 30 )
array_search() - Find the Key of a Value
$ages = ["Alice" => 25, "Bob" => 30];
$key = array_search(30, $ages);
echo $key;
array_filter() - Filter Array Elements
$numbers = [1, 2, 3, 4, 5, 6];
$evenNumbers = array_filter($numbers, fn($num) => $num % 2 == 0);
print_r($evenNumbers);
// Output: Array ( [1] => 2 [3] => 4 [5] => 6 )
array_map() - Apply a Function to Each Element
$numbers = [1, 2, 3];
$squared = array_map(fn($num) => $num * $num, $numbers);
print_r($squared);
// Output: Array ( [0] => 1 [1] => 4 [2] => 9 )
sort() - Sort an Array
$fruits = ["Banana", "Apple", "Cherry"];
sort($fruits);
print_r($fruits); // Output: Array ( [0] => Apple [1] => Banana [2] => Cherry )
rsort() - Sort an Array in Reverse Order
$fruits = ["Banana", "Apple", "Cherry"];
rsort($fruits);
print_r($fruits); // Output: Array ( [0] => Cherry [1] => Banana [2] => Apple )
usort() - Sort an Array Using a Custom Function
$fruits = ["Banana", "Apple", "Cherry"];
usort($fruits, fn($a, $b) => strlen($a) <=> strlen($b));
print_r($fruits); // Output: Array ( [0] => Apple [1] => Banana [2] => Cherry )
asort() - Sort an Associative Array by Value
$ages = ["Bob" => 30, "Alice" => 25];
asort($ages);
print_r($ages); // Output: Array ( [Alice] => 25 [Bob] => 30 )
ksort() - Sort an Associative Array by Key
$ages = ["Bob" => 30, "Alice" => 25];
ksort($ages);
print_r($ages); // Output: Array ( [Alice] => 25 [Bob] => 30 )