Importing with use keyword in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of class usage with alias

What is the output of this PHP code when using the use keyword with an alias?

PHP

<?php
namespace Animals\Mammals;
class Dog {
    public function speak() {
        return "Woof!";
    }
}

namespace Pets;
use Animals\Mammals\Dog as PetDog;
$dog = new PetDog();
echo $dog->speak();

A Nothing is printed

B Fatal error: Class 'Pets\Dog' not found

C Woof!

D Woof Woof!

💡 Hint

Remember that the use keyword imports the class with the alias, so you can create an instance using the alias name.

The use Animals\Mammals\Dog as PetDog; imports the Dog class under the alias PetDog. Creating new PetDog() calls the Dog class's speak method, which returns 'Woof!'.

❓ Predict Output

intermediate

Output when importing multiple classes

What will be the output of this PHP code that imports multiple classes using the use keyword?

PHP

<?php
namespace Vehicles\Land;
class Car {
    public function type() {
        return "Car";
    }
}
class Bike {
    public function type() {
        return "Bike";
    }
}

namespace Garage;
use Vehicles\Land\Car;
use Vehicles\Land\Bike;
$car = new Car();
$bike = new Bike();
echo $car->type() . " and " . $bike->type();

A Car and Car

B Car and Bike

C CarBike

D Fatal error: Class 'Garage\Bike' not found

💡 Hint

Each class is imported separately with its full namespace path.

Both classes Car and Bike are imported correctly. Creating instances and calling their type methods returns 'Car' and 'Bike', concatenated with ' and '.

❓ Predict Output

advanced

Output when importing functions with use keyword

What is the output of this PHP code that imports a function using the use function syntax?

PHP

<?php
namespace Math\Operations;
function add($a, $b) {
    return $a + $b;
}

namespace Calculator;
use function Math\Operations\add;
echo add(5, 7);

A 12

B Fatal error: Call to undefined function add()

C 57

D 5 + 7

💡 Hint

The use function imports a function from another namespace so it can be called directly.

The function add is imported from Math\Operations namespace. Calling add(5, 7) returns 12.

❓ Predict Output

advanced

Output when importing constants with use keyword

What will this PHP code output when importing a constant using the use const keyword?

PHP

<?php
namespace Config;
const VERSION = '1.2.3';

namespace App;
use const Config\VERSION;
echo "App version: " . VERSION;

A App version: 123

B App version: VERSION

C Fatal error: Undefined constant 'VERSION'

D App version: 1.2.3

💡 Hint

Constants can be imported with use const to be used without namespace prefix.

The constant VERSION is imported from Config namespace and used directly, printing 'App version: 1.2.3'.

❓ Predict Output

expert

Output when importing multiple elements with group use syntax

What is the output of this PHP code that uses group use syntax to import multiple classes and functions?

PHP

<?php
namespace Library\Utils {
    class Formatter {
        public static function format() {
            return "Formatted";
        }
    }
    function helper() {
        return "Helped";
    }
}

namespace App;
use Library\Utils\{Formatter, function helper};
echo Formatter::format() . " and " . helper();

A Formatted and Helped

B Fatal error: Class 'App\Formatter' not found

C Formatted and helper

D Helped and Formatted

💡 Hint

Group use syntax imports multiple elements from the same namespace in one statement.

The group use imports Formatter class and helper function. Calling Formatter::format() returns 'Formatted' and helper() returns 'Helped'.