Null coalescing operator in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign $value to $result if $value is set, otherwise assign 'default'.

PHP

$result = $value [1] 'default';

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

A||

B??

C&&

D?:

Attempts:

3 left

💡 Hint

Common Mistakes

Using '||' instead of '??' which checks for truthiness, not null.

Using '?:' which is the ternary shorthand but behaves differently.

The null coalescing operator '??' returns the left operand if it exists and is not null; otherwise, it returns the right operand.

2fill in blank

medium

Complete the code to get the value of $_GET['name'] or use 'Guest' if it is not set.

PHP

$name = $_GET['name'] [1] 'Guest';

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

A??

B&&

C?:

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using '||' which checks for truthiness and can cause unexpected results.

Using '?:' which requires the left operand to be evaluated differently.

The null coalescing operator '??' returns the left value if it exists and is not null; otherwise, it returns the right value.

3fill in blank

hard

Fix the error in the code to safely assign $username from $_POST['user'] or 'anonymous' if not set.

PHP

$username = $_POST['user'] [1] 'anonymous';

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

A||

B&&

C?:

D??

Attempts:

3 left

💡 Hint

Common Mistakes

Using '||' which can cause warnings if the key does not exist.

Using '?:' which requires the left operand to be set and truthy.

Using '??' avoids undefined index warnings by checking if the key exists and is not null.

4fill in blank

hard

Fill both blanks to create an array $settings with keys 'theme' and 'language' using null coalescing operator to provide defaults.

PHP

$settings = [
    'theme' => $userSettings['theme'] [1] 'light',
    'language' => $userSettings['language'] [2] 'en'
];

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

A??

B||

C?:

D&&

Attempts:

3 left

💡 Hint

Common Mistakes

Using '||' which checks truthiness and can cause unexpected results.

Using '?:' which behaves differently and may cause warnings.

The '??' operator safely returns the value if set and not null, otherwise the default value.

5fill in blank

hard

Fill all three blanks to assign $finalName using nested null coalescing operators to check $input['first'], $input['nickname'], or default to 'User'.

PHP

$finalName = $input['first'] [1] $input['nickname'] [2] [3];

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

A??

C'User'

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using '||' which checks truthiness and can cause unexpected results.

Not nesting the operators correctly.

Nested '??' operators check each value in order, returning the first that exists and is not null, else the default string.