A simple recursive function in PHP

Recursion means that the function calls itself to perform a process. For example, take a look at the following array:

Array
(
    [0] => 1
    [1] => 3
    [2] => 6
    [3] => Array
        (
            [0] => 8
            [1] => 10
            [2] => Array
                (
                    [0] => 30
                )
 
        )
 
)

If we need to know the maximun integer into the elements of an array with multiple nested arrays, we can do it by using a recursive function... like this:

$test = array(
  0 => 2,
  1 => 50,
  2 => array(
    0 => 20,
    3 => 10,
    4 => 40,
  )
);

function maxInteger($arr) { 

  foreach ($arr as $key => $value) {
    if (is_array($value)) {
      maxInteger($value);
    }
    
    if (is_numeric($value) &&  $value > $max) {
      $max = $value;
    }
    
  }
  return $max;
}

print maxInteger($test);

That's all folks!!