PHP Accessing Global classes

When PHP parser encounters an unqualified identifier such as class or function name, it resolves to current namespace. Therefore, to access PHP's predefined classes, they must be referred to by their fully qualified name by prefixing \.

Using Built-in Classes

In following example, a new class uses predefined stdClass as base class. We refer it by prefixing \ to specify global class ?

<?php
namespace testspace;
class testclass extends \stdClass{
    //
}
$obj = new testclass();
$obj->name = "Raju";
echo $obj->name;
?>

Raju

Accessing Classes from Included Files

Included files will default to the global namespace. Hence, to refer to a class from included file, it must be prefixed with \.

Creating a Global Class

First, let's create a file with a class in global namespace ?

// test1.php
<?php
class myclass{
    function hello(){ 
        echo "Hello World<br>";
    }
}
?>

Including and Extending Global Class

When this file is included in another namespace, we must use \ to access the global class ?

<?php
// Simulating included content
class myclass{
    function hello(){ 
        echo "Hello World<br>";
    }
}

namespace testspace;

class testclass extends \myclass{
    function hello(){
        echo "Hello PHP<br>"; 
    }
}

$obj1 = new \myclass();
$obj1->hello();
$obj2 = new testclass();
$obj2->hello();
?>

Hello World
Hello PHP

Conclusion

Always prefix global classes and functions with \ when working within namespaces to ensure proper resolution. This applies to both PHP's built-in classes and user-defined classes from included files.