Interface constants in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a constant named VERSION inside the interface.

PHP

<?php
interface AppInfo {
    const [1] = '1.0';
}
?>

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

ACONST_VERSION

BVERSION

CAppVersion

Dversion

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase names for constants.

Trying to use variables instead of constants.

The constant name inside an interface should be uppercase and descriptive. 'VERSION' is the correct constant name here.

2fill in blank

medium

Complete the code to access the constant MAX_USERS from the interface UserLimits.

PHP

<?php
interface UserLimits {
    const MAX_USERS = 100;
}

echo UserLimits::[1];
?>

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AMAX_USERS

BMaxUsers

Cmax_users

DmaxUsers

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or camelCase names when accessing constants.

Trying to access constants as variables.

Constants are accessed with the interface name followed by :: and the constant name exactly as defined, which is 'MAX_USERS'.

3fill in blank

hard

Fix the error in the code by completing the blank to correctly access the constant.

PHP

<?php
interface Config {
    const TIMEOUT = 30;
}

class App implements Config {
    public function getTimeout() {
        return self::[1];
    }
}
?>

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

Atimeout

BConfig::TIMEOUT

CTIMEOUT

Dself::TIMEOUT

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use the interface name with :: inside the class method.

Using lowercase constant names.

Inside the class implementing the interface, constants from the interface are accessed with self::CONSTANT_NAME. So 'TIMEOUT' is correct.

4fill in blank

hard

Fill both blanks to create a dictionary of constants from the interface with a condition.

PHP

<?php
interface StatusCodes {
    const OK = 200;
    const NOT_FOUND = 404;
    const ERROR = 500;
}

$codes = [
    'success' => StatusCodes::[1],
    'failure' => StatusCodes::[2]
];
?>

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AOK

BNOT_FOUND

CERROR

DSUCCESS

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined constant names.

Mixing up the success and failure codes.

'success' should map to the OK code (200), and 'failure' should map to ERROR (500) from the interface constants.

5fill in blank

hard

Fill all three blanks to define an interface with constants and use them in a class method.

PHP

<?php
interface Settings {
    const [1] = 'dark';
    const [2] = 24;
}

class UserSettings implements Settings {
    public function getTheme() {
        return self::[3];
    }
}
?>

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

ATHEME

BFONT_SIZE

DFONT

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent constant names between interface and class.

Using lowercase or partial names.

The interface defines THEME and FONT_SIZE constants. The class method returns THEME using self::THEME.