How to Randomly Shuffle Arrays in PHP: shuffle() and array_rand() Explained

In PHP, several built-in functions can randomize the order of an array’s elements.

shuffle()

The shuffle() function shuffles an array in place, directly modifying the original array.

<?php
$arr = [1, 2, 3, 4, 5];
shuffle($arr);
print_r($arr); // outputs the shuffled array
?>

array_rand()

array_rand()

returns one or more random keys from an array; these keys can then be used to reorder the array.

<?php
$arr = [1, 2, 3, 4, 5];
$keys = array_rand($arr, 3); // returns 3 random keys
$sortedArr = [];
foreach ($keys as $key) {
    $sortedArr[] = $arr[$key];
}
print_r($sortedArr); // outputs the reordered array
?>

Practical example

Suppose you have a list of student names that need to be randomly assigned to two classes. The following code shuffles the list and then splits it into two groups.

<?php
$students = ['John', 'Mary', 'Bob', 'Alice', 'Tom'];
shuffle($students);
// Divide students into two classes
$class1 = array_slice($students, 0, 3);
$class2 = array_slice($students, 3);
print_r($class1); // first class
print_r($class2); // second class
?>