Sorting a Multi-dimensional Array by Value

In PHP, you can sort a multi-dimensional array by its values using various sorting functions available.

Using usort() Function

The usort() Function

The usort() function is a built-in PHP function that sorts an array using a user-defined comparison function. This function allows you to sort multi-dimensional arrays based on the values of a specific key.

Syntax of usort()

usort($array, function($a, $b) {
    // Comparison logic here
});

Example

$students = array(
    array('name' => 'John', 'age' => 25),
    array('name' => 'Jane', 'age' => 22),
    array('name' => 'Bob', 'age' => 30)
);

// Sort the students array based on age in ascending order
usort($students, function($a, $b) {
    return $a['age'] - $b['age'];
});

// Print the sorted array
print_r($students);

Output:

Array
(
    [0] => Array
        (
            [name] => Jane
            [age] => 22
        )

    [1] => Array
        (
            [name] => John
            [age] => 25
        )

    [2] => Array
        (
            [name] => Bob
            [age] => 30
        )
)

In this example, the usort() function is used with an anonymous function as the comparison logic. The array is sorted based on the 'age' key in ascending order.

Using array_multisort() Function

The array_multisort() Function

The array_multisort() function is another built-in PHP function that can sort multiple arrays or multi-dimensional arrays simultaneously based on the values.

Syntax of array_multisort()

array_multisort($array1, $sortingOrder1, $array2, $sortingOrder2, ...);

Example

$names = array('John', 'Jane', 'Bob');
$ages = array(25, 22, 30);

// Sort the arrays simultaneously based on ages in ascending order
array_multisort($ages, SORT_ASC, $names, SORT_ASC);

// Print the sorted arrays
print_r($names);
print_r($ages);

Output:

Array
(
    [0] => Jane
    [1] => John
    [2] => Bob
)
Array
(
    [0] => 22
    [1] => 25
    [2] => 30
)

In this example, the array_multisort() function is used to sort both the 'names' and 'ages' arrays simultaneously based on the 'ages' in ascending order.