PHP check whether property exists in object or class

I understand PHP does not have a pure object variable, but I want to check whether a property is in the given object or class.

$ob = (object) array('a' => 1, 'b' => 12); 

or

$ob = new stdClass;
$ob->a = 1;
$ob->b = 2;

In JS, I can write this to check if variable a exists in an object:

if ('a' in ob)

In PHP, can anything like this be done?

property_exists( mixed $class , string $property )

if (property_exists($ob, 'a')) 

isset( mixed $var [, mixed $... ] )

NOTE : Mind that isset() will return false if property is null

if (isset($ob->a))

Example 1:

$ob->a = null
var_dump(isset($ob->a)); // false

Example 2:

class Foo
{
   public $bar = null;
}

$foo = new Foo();

var_dump(property_exists($foo, 'bar')); // true
var_dump(isset($foo->bar)); // false

To check if the property exists and if it's null too, you can use the function property_exists().

Docs: http://php.net/manual/en/function.property-exists.php

As opposed with isset(), property_exists() returns TRUE even if the property has the value NULL.

bool property_exists ( mixed $class , string $property )

Example:

if (property_exists($testObject, $property)) {
    //do something
}