What potential pitfalls should beginners be aware of when using the usort() function in PHP?

Beginners using the usort() function in PHP should be aware of potential pitfalls such as not providing a valid comparison function or incorrectly implementing the comparison logic, which can lead to unexpected sorting results or errors. To avoid these issues, make sure to carefully define and test the comparison function before using it with usort().

// Example of using usort() with a properly defined comparison function
function customSort($a, $b) {
    if ($a == $b) {
        return 0;
    }
    return ($a < $b) ? -1 : 1;
}

$data = [3, 1, 2];
usort($data, 'customSort');

print_r($data);