Multidimensional arrays in PHP

Multi-dimensional arrays in PHP are arrays that store other arrays as their elements. Each dimension adds complexity, requiring multiple indices to access elements. Common forms include two-dimensional arrays (like tables) and three-dimensional arrays, useful for organizing complex, structured data.

Dimensions

Dimensions of multidimensional array indicates the number of indices needed to select an element. For a two dimensional array two indices to select an element.

Two dimensional array

It is the simplest form of a multidimensional array. It can be created using nested array. These type of arrays can be used to store any type of elements, but the index is always a number. By default, the index starts with zero.

Syntax:

array (
    array (elements...),
    array (elements...),
    ...
)

Example: In this example we creates a two-dimensional array containing names and locations. The print_r() function is used to display the structure and contents of the array, showing the nested arrays and their values.

<?php

// PHP program to create 
// multidimensional array

// Creating multidimensional
// array
$myarray = array(
    
    // Default key for each will
    // start from 0
    array("Ankit", "Ram", "Shyam"),
    array("Unnao", "Trichy", "Kanpur")
);
    
// Display the array information
print_r($myarray);
?>

Array
(
    [0] => Array
        (
            [0] => Ankit
            [1] => Ram
            [2] => Shyam
        )

    [1] => Array
        (
            [0] => Unnao
            [1] => Trichy
            [2] => Kanpur
        )

)

Two dimensional associative array

Al associative array is similar to indexed array but instead of linear storage (indexed storage), every value can be assigned with a user-defined key of string type.

Example: In this example we creates a two-dimensional associative array to store students' marks for various subjects. The print_r() function displays the array, showing each student's name as a key with subject-marks pairs.

<?php

// PHP program to creating two 
// dimensional associative array
$marks = array(
    
    // Ankit will act as key
    "Ankit" => array(
        
        // Subject and marks are
        // the key value pair
        "C" => 95,
        "DCO" => 85,
        "FOL" => 74,
    ),
        
    // Ram will act as key
    "Ram" => array(
        
        // Subject and marks are
        // the key value pair
        "C" => 78,
        "DCO" => 98,
        "FOL" => 46,
    ),
    
    // Anoop will act as key
    "Anoop" => array(
        
        // Subject and marks are
        // the key value pair
        "C" => 88,
        "DCO" => 46,
        "FOL" => 99,
    ),
);

echo "Display Marks: \n";
    
print_r($marks);
?>

Display Marks: 
Array
(
    [Ankit] => Array
        (
            [C] => 95
            [DCO] => 85
            [FOL] => 74
        )

    [Ram] => Array
        (
            [C] => 78
            [DCO] => 98
            [FOL] => 46
        )

    [Anoop] => Array
        (
            [C] => 88
            [DCO] => 46
            [FOL] => 99
        )

)

Three Dimensional Array

It is the form of multidimensional array. Initialization in Three-Dimensional array is same as that of Two-dimensional arrays. The difference is as the number of dimension increases so the number of nested braces will also increase.

Syntax:

array (
    array (
        array (elements...),
        array (elements...),
        ...
    ),
    array (
        array (elements...),
        array (elements...),
        ...
    ),
    ...
)

Example: In this example we creates a three-dimensional array with nested arrays containing numeric values. The print_r() function is used to display the structure and contents of the entire array.

<?php

// PHP program to creating three
// dimensional array

// Create three nested array
$myarray = array(
    array(
        array(1, 2),
        array(3, 4),
    ),
    array(
        array(5, 6),
        array(7, 8),
    ),
);
    
// Display the array information
print_r($myarray);
?>

Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [0] => 1
                    [1] => 2
                )

            [1] => Array
                (
                    [0] => 3
                    [1] => 4
                )

        )

    [1] => Array
        (
            [0] => Array
                (
                    [0] => 5
                    [1] => 6
                )

            [1] => Array
                (
                    [0] => 7
                    [1] => 8
                )

        )

)

Accessing multidimensional array elements

There are mainly two ways to access multidimensional array elements in PHP.

• Elements can be accessed using dimensions as array_name['first dimension']['second dimension'].
• Elements can be accessed using for loop.
• Elements can be accessed using for each loop.

Example: In this example we creates a multi-dimensional associative array to store students' marks by subject. It displays specific marks and iterates through the array using a foreach loop to print values.

<?php

// PHP code to create 
// multidimensional array

// Creating multidimensional
// associative array
$marks = array(
    
    // Ankit will act as key
    "Ankit" => array(
        
        // Subject and marks are 
        // the key value pair
        "C" => 95,
        "DCO" => 85,
        "FOL" => 74,
    ),
        
    // Ram will act as key
    "Ram" => array(
        
        // Subject and marks are 
        // the key value pair
        "C" => 78,
        "DCO" => 98,
        "FOL" => 46,
    ),
    
    // Anoop will act as key
    "Anoop" => array(
        
        // Subject and marks are
        // the key value pair
        "C" => 88,
        "DCO" => 46,
        "FOL" => 99,
    ),
);

// Accessing the array element 
// using dimensions 
    
// It will display the marks of
// Ankit in C subject
echo $marks['Ankit']['C'] . "\n"; 
    
// Accessing array elements using for each loop
foreach($marks as $mark) {
    echo $mark['C']. " ".$mark['DCO']." ".$mark['FOL']."\n"; 
}
    
?>

95
95 85 74
78 98 46
88 46 99

PHP is a server-side scripting language designed specifically for web development. You can learn PHP from the ground up by following this PHP Tutorial and PHP Examples.