Differentiate an associative array from a regular array

Question

Without having to change the function signature, I'd like a PHP function to behave differently if given an associative array instead of a regular array.

Note: You can assume arrays are homogenous. E.g., array(1,2,"foo" => "bar") is not accepted and can be ignored.

function my_func(Array $foo){
  if (…) {
    echo "Found associative array";
  }
  else {
    echo "Found regular array";
  }
}


my_func(array("foo" => "bar", "hello" => "world"));
# => "Found associative array"

my_func(array(1,2,3,4));
# => "Found regular array"

Is this possible with PHP?

Answer 1

Just check the type of any key:

function is_associative(array $a) {
    return is_string(key($a));
}

$a = array(1 => 0);
$a2 = array("a" => 0);

var_dump(is_associative($a)); //false
var_dump(is_associative($a2)); //true