Union types in practice in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function that accepts an int or a string.

PHP

<?php
function printValue([1] $value) {
    echo $value;
}
?>

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

Astring

Bint&string

Cint|string|null

Dint|string

Attempts:

3 left

💡 Hint

Common Mistakes

Using & instead of | for union types.

Adding null when not needed.

Using only one type instead of a union.

The union type int|string allows the function to accept either an integer or a string.

2fill in blank

medium

Complete the code to declare a variable that can hold either an array or null.

PHP

<?php
/** @var [1] $data */
$data = null;
?>

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

Aarray&null

Barray|null

Carray|string

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using & instead of |.

Using unrelated types like string.

Not including null when needed.

The union type array|null means the variable can be an array or null.

3fill in blank

hard

Fix the error in the function parameter type declaration to accept int or float.

PHP

<?php
function calculateArea([1] $radius) {
    return pi() * $radius * $radius;
}
?>

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

Aint|float

Bfloat

Cint&float

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using & instead of |.

Using only one type.

Using unrelated types.

The union type int|float allows the function to accept either an integer or a float.

4fill in blank

hard

Fill both blanks to declare a function that returns int or string and accepts int or string.

PHP

<?php
function convert([1] $input): [2] {
    if (is_int($input)) {
        return (string)$input;
    }
    return strlen($input);
}
?>

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

Aint|string

Bstring

Cint

Dfloat

Attempts:

3 left

💡 Hint

Common Mistakes

Using different types for parameter and return.

Using only one type instead of union.

Using unrelated types like float.

The function accepts int|string and returns int|string as a union type.

5fill in blank

hard

Fill all three blanks to create a function that accepts int|string|null and returns string|int|null.

PHP

<?php
function processValue([1] $value): [2] {
    if ($value === null) {
        return null;
    }
    if (is_int($value)) {
        return (string)$value;
    }
    return strlen($value);
}

/** @var [3] $result */
$result = processValue(123);
?>

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

Aint|string|null

Bstring|int|null

Dstring|null

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up order of types in unions.

Not including null when needed.

Using only one type instead of union.

The function parameter uses int|string|null, the return type is string|int|null, and the variable is declared with int|string|null.