PHP Arrays Basics
Introduction
Arrays are one of the most powerful and essential data structures in PHP. They allow you to store multiple values in a single variable, making data organization and manipulation much more efficient. Whether you're building a simple contact form or a complex web application, understanding PHP arrays is crucial for your journey as a PHP developer.
In this tutorial, we'll explore the fundamentals of PHP arrays, including how to create them, access their elements, and perform basic operations. By the end, you'll have a solid foundation in working with arrays in PHP.
What is an Array?
An array in PHP is a special variable that can hold multiple values under a single name. You can think of an array as a collection of related items, like a list of student names, product prices, or user information.
Types of Arrays in PHP
PHP supports three main types of arrays:
- Indexed Arrays: Arrays with numeric indices
- Associative Arrays: Arrays with named keys
- Multidimensional Arrays: Arrays containing one or more arrays
Let's examine each type in detail.
Creating Arrays in PHP
1. Indexed Arrays
Indexed arrays use numeric indices that typically start at 0. There are several ways to create indexed arrays in PHP.
Method 1: Using the array() function
<?php
// Creating an indexed array using array() function
$fruits = array("Apple", "Banana", "Cherry", "Orange");
// Print the array
print_r($fruits);
?>
Output:
Array
(
[0] => Apple
[1] => Banana
[2] => Cherry
[3] => Orange
)
Method 2: Using short array syntax (PHP 5.4+)
<?php
// Creating an indexed array using short syntax
$fruits = ["Apple", "Banana", "Cherry", "Orange"];
// Print the array
print_r($fruits);
?>
Output:
Array
(
[0] => Apple
[1] => Banana
[2] => Cherry
[3] => Orange
)
Method 3: Defining indices explicitly
<?php
// Creating an indexed array with explicit indices
$fruits = array();
$fruits[0] = "Apple";
$fruits[1] = "Banana";
$fruits[2] = "Cherry";
$fruits[3] = "Orange";
// Print the array
print_r($fruits);
?>
Output:
Array
(
[0] => Apple
[1] => Banana
[2] => Cherry
[3] => Orange
)
2. Associative Arrays
Associative arrays use named keys instead of numeric indices. This makes them extremely useful when you want to store data that can be associated with specific labels.
<?php
// Creating an associative array
$employee = array(
"name" => "John Smith",
"age" => 35,
"position" => "Web Developer",
"department" => "IT"
);
// Print the array
print_r($employee);
?>
Output:
Array
(
[name] => John Smith
[age] => 35
[position] => Web Developer
[department] => IT
)
Using short syntax:
<?php
// Creating an associative array with short syntax
$employee = [
"name" => "John Smith",
"age" => 35,
"position" => "Web Developer",
"department" => "IT"
];
// Print the array
print_r($employee);
?>
3. Multidimensional Arrays
Multidimensional arrays are arrays containing one or more arrays. They're useful for storing complex data structures like tables or matrices.
<?php
// Creating a multidimensional array
$employees = [
[
"name" => "John Smith",
"age" => 35,
"position" => "Web Developer"
],
[
"name" => "Sarah Johnson",
"age" => 28,
"position" => "UX Designer"
],
[
"name" => "Michael Brown",
"age" => 42,
"position" => "Project Manager"
]
];
// Print the array
print_r($employees);
?>
Output:
Array
(
[0] => Array
(
[name] => John Smith
[age] => 35
[position] => Web Developer
)
[1] => Array
(
[name] => Sarah Johnson
[age] => 28
[position] => UX Designer
)
[2] => Array
(
[name] => Michael Brown
[age] => 42
[position] => Project Manager
)
)
Accessing Array Elements
Accessing Indexed Arrays
To access elements in an indexed array, you use the array name followed by the index in square brackets.
<?php
$fruits = ["Apple", "Banana", "Cherry", "Orange"];
// Accessing array elements
echo "First fruit: " . $fruits[0] . "<br>";
echo "Second fruit: " . $fruits[1] . "<br>";
echo "Third fruit: " . $fruits[2] . "<br>";
?>
Output:
First fruit: Apple
Second fruit: Banana
Third fruit: Cherry
Accessing Associative Arrays
For associative arrays, you use the named key instead of a numeric index.
<?php
$employee = [
"name" => "John Smith",
"age" => 35,
"position" => "Web Developer",
"department" => "IT"
];
// Accessing array elements
echo "Name: " . $employee["name"] . "<br>";
echo "Age: " . $employee["age"] . "<br>";
echo "Position: " . $employee["position"] . "<br>";
?>
Output:
Name: John Smith
Age: 35
Position: Web Developer
Accessing Multidimensional Arrays
To access elements in a multidimensional array, you need to use multiple indices.
<?php
$employees = [
[
"name" => "John Smith",
"age" => 35,
"position" => "Web Developer"
],
[
"name" => "Sarah Johnson",
"age" => 28,
"position" => "UX Designer"
]
];
// Accessing elements in a multidimensional array
echo "First employee name: " . $employees[0]["name"] . "<br>";
echo "Second employee position: " . $employees[1]["position"] . "<br>";
?>
Output:
First employee name: John Smith
Second employee position: UX Designer
Common Array Operations
1. Getting Array Length
The count() function returns the number of elements in an array.
<?php
$fruits = ["Apple", "Banana", "Cherry", "Orange"];
echo "Number of fruits: " . count($fruits);
?>
Output:
Number of fruits: 4
2. Adding Elements to an Array
You can add elements to an array in several ways:
<?php
// Method 1: Add element to the end of an indexed array
$fruits = ["Apple", "Banana", "Cherry"];
$fruits[] = "Orange"; // Adds to the end of the array
// Method 2: Using array_push() to add one or more elements
array_push($fruits, "Mango", "Grapes");
// Method 3: Add element to an associative array
$employee = [
"name" => "John Smith",
"age" => 35
];
$employee["position"] = "Web Developer"; // Adds a new key-value pair
print_r($fruits);
print_r($employee);
?>
Output:
Array
(
[0] => Apple
[1] => Banana
[2] => Cherry
[3] => Orange
[4] => Mango
[5] => Grapes
)
Array
(
[name] => John Smith
[age] => 35
[position] => Web Developer
)
3. Removing Elements from an Array
PHP provides several functions to remove elements from arrays:
<?php
$fruits = ["Apple", "Banana", "Cherry", "Orange", "Mango"];
// Remove the last element
$last = array_pop($fruits);
echo "Removed last element: $last<br>";
// Remove the first element
$first = array_shift($fruits);
echo "Removed first element: $first<br>";
// Remove a specific element (removes "Cherry" at index 1)
unset($fruits[1]);
print_r($fruits);
?>
Output:
Removed last element: Mango
Removed first element: Apple
Array
(
[1] => Banana
)
4. Checking if an Element Exists
Use the in_array() function to check if a value exists in an array or array_key_exists() to check if a key exists.
<?php
$fruits = ["Apple", "Banana", "Cherry", "Orange"];
// Check if value exists
if (in_array("Banana", $fruits)) {
echo "Banana is in the fruits array.<br>";
}
// Check if key exists
$employee = ["name" => "John", "age" => 35];
if (array_key_exists("age", $employee)) {
echo "Age key exists in the employee array.";
}
?>
Output:
Banana is in the fruits array.
Age key exists in the employee array.
Practical Examples
Example 1: Shopping Cart
A simple shopping cart using associative arrays:
<?php
// Shopping cart items
$cart = [
[
"product_id" => 101,
"name" => "PHP for Beginners Book",
"price" => 29.99,
"quantity" => 1
],
[
"product_id" => 202,
"name" => "Web Development Course",
"price" => 199.00,
"quantity" => 1
],
[
"product_id" => 303,
"name" => "Code Editor Pro License",
"price" => 59.99,
"quantity" => 2
]
];
// Calculate total
$total = 0;
echo "<h3>Shopping Cart</h3>";
echo "<ul>";
foreach ($cart as $item) {
$itemTotal = $item["price"] * $item["quantity"];
$total += $itemTotal;
echo "<li>{$item["name"]} - {$item["quantity"]} x \${$item["price"]} = \$" . number_format($itemTotal, 2) . "</li>";
}
echo "</ul>";
echo "<strong>Total: \$" . number_format($total, 2) . "</strong>";
?>
Output:
Shopping Cart
• PHP for Beginners Book - 1 x $29.99 = $29.99
• Web Development Course - 1 x $199.00 = $199.00
• Code Editor Pro License - 2 x $59.99 = $119.98
Total: $348.97
Example 2: Student Grades Tracker
Using arrays to store and calculate student grades:
<?php
// Student grades
$students = [
"John" => [85, 90, 78, 88, 95],
"Sarah" => [92, 88, 94, 90, 89],
"Michael" => [75, 80, 85, 72, 78]
];
// Calculate average grades
echo "<h3>Student Grade Averages</h3>";
echo "<table border='1' cellpadding='5'>";
echo "<tr><th>Student</th><th>Average Grade</th><th>Status</th></tr>";
foreach ($students as $name => $grades) {
$average = array_sum($grades) / count($grades);
$status = ($average >= 80) ? "Passed" : "Needs Improvement";
$statusColor = ($average >= 80) ? "green" : "red";
echo "<tr>";
echo "<td>$name</td>";
echo "<td>" . number_format($average, 1) . "</td>";
echo "<td style='color: $statusColor'>$status</td>";
echo "</tr>";
}
echo "</table>";
?>
Output:
Student Grade Averages
Student | Average Grade | Status
--------|---------------|--------
John | 87.2 | Passed
Sarah | 90.6 | Passed
Michael | 78.0 | Needs Improvement
Summary
In this tutorial, we've covered the basics of PHP arrays, including:
- What arrays are and why they're important
- Different types of arrays (indexed, associative, and multidimensional)
- How to create arrays using various methods
- Accessing array elements
- Common array operations like adding, removing, and finding elements
- Practical examples demonstrating real-world applications
Arrays are fundamental to PHP programming and form the backbone of data manipulation in web applications. Mastering arrays will significantly enhance your ability to build dynamic and data-driven websites.
Exercises
To practice your PHP array skills, try these exercises:
- Create an indexed array of your five favorite movies and display them in an ordered list.
- Create an associative array representing a book with properties like title, author, year, and genre, then display the information in a formatted way.
- Create a multidimensional array to store information about three different countries (name, capital, population, languages) and display the data in a table.
- Write a script that finds the maximum and minimum values in an array of numbers.
- Create a simple to-do list application that stores tasks in an array and allows adding and removing tasks.
Additional Resources
For more information about PHP arrays, check out these resources:
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