PHP 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 deeper than three levels are hard to manage for most people.

1. Two-Dimensional Arrays

A two-dimensional array is like a table with rows and columns. Imagine we have the following data:

We can store this data in a 2D array like this:

<?php
    $cars = [
        ["Volvo", 22, 18],
        ["BMW", 15, 13],
        ["Saab", 5, 2]
    ];
?>

2. Accessing Elements

To access an element, we must point to the two indices (row and column):

<?php
    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>";
?>

3. Looping Through Nested Arrays

To display the entire contents of a multidimensional array, we use a nested loop — a loop inside another loop.

<?php
    for ($row = 0; $row < 3; $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>";
    }
?>

Key Points to Remember

• A multidimensional array is simply an array of arrays.
• 2D arrays are the most common, used for tabular data.
• Use multiple brackets (e.g., [0][1]) to access inner data.
• Iteration requires nested loops (one for each dimension).
• Keep complexity low; avoid nesting too many levels deep.