Why Difference between call_user_func and call_user_func_array() return types

Question

I was trying to get a clear difference between methods call_user_func() and call_user_func_array() when I stumbled upon a difference in return types that wasn't apparent to me before.Consider the class Test with a method dnd($t):

class Test {
function dnd($t) {
    echo "<pre>";
    var_dump($t);
    echo "</pre>";
  }
 }

Instantiate:

$obj = new Test();
$params = [33,22,'fff'];

Now calling by call_user_func method

call_user_func([$obj,'dnd'], $params);

This results in:

array(3) {
 [0]=>
     int(33)
 [1]=>
     int(22)
 [2]=>
     string(3) "fff"
 }

While call_user_func_array:

call_user_func_array([$obj,'dnd'], $params);

yields:

int(33)

Why this variation and what impact does it have on parameters passed to functions or function calls that rely on parameters?

Answer 1

In the second parameter call_user_func receives the 'arguments' separately.
So our only argument is the array.

$t = [33,22,'fff']

The second parameter call_user_func_array receives the 'arguments' in the form of an array and sends them to the desired function.
As a result, the first array index is used as the only argument.

$t = int(33) // int(22) and 'fff' are the second and third arguments of the dnd() method (not defined here)