Instanceof operator in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if $obj is an instance of the class MyClass.

PHP

<?php
class MyClass {}
$obj = new MyClass();
if ($obj [1] MyClass) {
    echo "Yes";
} else {
    echo "No";
}
?>

Drag options to blanks, or click blank then click option'

A===

B==

Cinstanceof

Dis_a

Attempts:

3 left

💡 Hint

Common Mistakes

Using == or === instead of instanceof.

Using is_a as if it were an operator.

The instanceof operator checks if an object is an instance of a specific class.

2fill in blank

medium

Complete the code to check if $animal is an instance of the class Dog.

PHP

<?php
class Dog {}
class Cat {}
$animal = new Dog();
if ($animal [1] Dog) {
    echo "It's a dog.";
} else {
    echo "It's not a dog.";
}
?>

Drag options to blanks, or click blank then click option'

A==

Binstanceof

Cis_a

D===

Attempts:

3 left

💡 Hint

Common Mistakes

Using == or === which compare values, not types.

Trying to use is_a as an operator.

instanceof checks if $animal is an instance of Dog or its subclass.

3fill in blank

hard

Fix the error in the code to correctly check if $obj is an instance of MyInterface.

PHP

<?php
interface MyInterface {}
class MyClass implements MyInterface {}
$obj = new MyClass();
if ($obj [1] MyInterface) {
    echo "Implements interface.";
} else {
    echo "Does not implement interface.";
}
?>

Drag options to blanks, or click blank then click option'

A===

B==

Cis_a

Dinstanceof

Attempts:

3 left

💡 Hint

Common Mistakes

Using == or === which do not check interface implementation.

Trying to use is_a as an operator.

instanceof works with interfaces to check if an object implements them.

4fill in blank

hard

Fill in the blank to create a dictionary with words as keys and their lengths as values, but only for words longer than 3 characters.

PHP

<?php
$words = ['apple', 'cat', 'banana', 'dog'];
$lengths = array_filter(array_combine($words, array_map(function($word) {
    return strlen($word);
}, $words)), function($length) {
    return $length [1] 3;
});
print_r($lengths);
?>

Drag options to blanks, or click blank then click option'

A>

B<

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using < or == which filter wrong lengths.

Using != which includes unwanted lengths.

We want lengths greater than 3, so use > operator.

5fill in blank

hard

Fill all three blanks to create an associative array with uppercase words as keys and their lengths as values, only for words longer than 3 characters.

PHP

<?php
$words = ['apple', 'cat', 'banana', 'dog'];
$lengths = array_filter(array_combine(array_map(function($word) {
    return [1];
}, $words), array_map(function($word) {
    return [2];
}, $words)), function($length) {
    return $length [3] 3;
});
print_r($lengths);
?>

Drag options to blanks, or click blank then click option'

A$word strtoupper($word)

Bstrlen($word)

C>

Dstrtoupper($word)

Attempts:

3 left

💡 Hint

Common Mistakes

Using $word instead of strtoupper($word) for keys.

Using wrong comparison operator in filter.

Mixing keys and values in array_combine.

Use strtoupper($word) for keys, strlen($word) for values, and > 3 to filter lengths.