Checking if array is multidimensional or not?

Question

1. What is the most efficient way to check if an array is a flat array of primitive values or if it is a multidimensional array?

Answer 1

The native print_r function returns a human-readable string. Just count the "Array" instances.

try...

substr_count(print_r([...array...], true), 'Array') > 1;

$a = array(1 => 'a',2 => 'b',3 => array(1,2,3));
$b = array(1 => 'a',2 => 'b');
$c = array(1 => 'a',2 => 'b','foo' => array(1,array(2)));
$d = array(array());
$e = array(1, array());
$f = array(array(), array());
$g = array("hello", "hi" => "hi there");
$h[] = $g;

var_dump(substr_count(print_r($a, true), 'Array') > 1);
...

//a: bool(true)
//b: bool(false)
//c: bool(true)
//d: bool(true)
//e: bool(true)
//f: bool(true)
//g: bool(false)
//h: bool(true)

On my box, "is_multi took 0.83681297302246 seconds in 500000 times"

Courtesy: Ruach HaKodesh