Is there equivalent for __toString() method for other simple types in PHP?

_toString() is called when an object is used as string. How can I do something similar for numerical values, something like __toInt(), or __toArray(). Do such methods exist? Is there a work around? Is it a bad idea to use something like that even if there is a workaround for it?

There is no __toArray magic-method (just check the ones that exist here), but then, there shouldn't be, IMO.
Though people have asked for a magic toArray method, it doesn't look like such a method will be implemented any time soon.

Considering what objects are for, and how we use them, a toInt method wouldn't make much sense, and since all objects can be cast to an array, and can be iterated over, I see very little point in using __toArray anyway.
To "convert" on object to an array, you can use either one of the following methods:

$obj = new stdClass;
$obj->foo = 'bar';
var_dump((array) $obj);
//or
var_dump(json_decode(json_encode($obj), true));

This can be done with both custom objects, as stdClass instances alike.
As far as accessing them as an array, I can't see the point. Why write a slow magic method to be able to do something like:

$bar = 'foo';
$obj[$bar];

if you can do:

$obj->{$bar}

or if you can do:

foreach($obj as $property => $value){}

Or, if you need something a tad more specific, just implement any of the Traversable interfaces.
And for those rare cases, where you want an object to produce an array from specific properties in a very particular way, just write a method for that and call that method explicitly.

class ComplexObject
{
    private $secret = null;
    private $childObject = null;
    public $foo = null;
    //some methods, then:
    public function toArray()
    {//custom array representation of object
        $data = array();
        foreach($this->childObject as $property => $val)
        {
            if (!is_object($this->childObject->{$property}))
            {
                $data[$property] = $val;
            }
        }
        $data['foo'] = $this->foo;
        return $data;
    }
    //and even:
    public function toJson()
    {
        return json_encode($this->toArray());
    }
}

Ok, you have to call these methods yourself, explicitly, but that's not that hard, really... is it?