Determining Property Existence in PHP

Unlike JavaScript, PHP does not inherently possess pure object variables. However, ascertaining whether a property exists within an object or class is possible using various approaches.

property_exists() Method

The property_exists() function allows for explicit checks on property existence. Its syntax is:

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

where $ob is the object or class instance.

isset() Method

Alternatively, isset() can verify if a property is set within an object. However, it's crucial to note that isset() returns false if the property's value is null.

if (isset($ob->a))

Here's an example demonstrating the differences:

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

Even though the property exists, isset() returns false due to the null value.

class Foo
{
   public $bar = null;
}

$foo = new Foo();

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

In this scenario, property_exists() returns true since the property is defined, while isset() returns false because the value is null.