Constants in classes in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a constant in a PHP class?

A constant in a PHP class is a fixed value that cannot be changed once set. It is defined using the <code>const</code> keyword and is accessed without creating an object.

beginner

How do you define a constant inside a PHP class?

Use the <code>const</code> keyword followed by the constant name and value. For example: <code>const PI = 3.14;</code>

beginner

How do you access a class constant from outside the class?

Use the class name followed by the scope resolution operator <code>::</code> and the constant name. For example: <code>ClassName::CONSTANT_NAME</code>

beginner

Can class constants be changed after they are defined?

No, class constants cannot be changed after they are defined. They are fixed values throughout the program.

intermediate

What is the difference between a class constant and a class property?

A class constant is a fixed value defined with <code>const</code> and cannot change. A class property is a variable that can hold different values and can be changed.

How do you define a constant inside a PHP class?

A Using the <code>var</code> keyword

B Using the <code>const</code> keyword

C Using the <code>static</code> keyword

D Using the <code>define()</code> function

Class constants are defined using the const keyword inside the class.

How do you access a class constant from outside the class?

A Using <code>ClassName::CONSTANT</code>

B Using <code>$object->CONSTANT</code>

C Using <code>$object::CONSTANT</code>

D Using <code>ClassName->CONSTANT</code>

Class constants are accessed with the class name and the scope resolution operator ::.

Can you change the value of a class constant after it is set?

A Yes, anytime

B Only inside the class constructor

C No, constants are immutable

D Only if declared as <code>static</code>

Class constants cannot be changed once defined; they are immutable.

Which keyword is NOT used to define a class constant?

A var

B const

C define

D static

var is used for properties, not constants.

What is the correct way to define a constant named VERSION with value '1.0' inside a class?

A define('VERSION', '1.0');

B static $VERSION = '1.0';

C var VERSION = '1.0';

D const VERSION = '1.0';

Class constants are defined with const followed by the name and value.

Explain how to define and access a constant inside a PHP class.

Think about how constants are fixed and how you call them without creating an object.

Describe the difference between a class constant and a class property in PHP.

Consider mutability and how you use each in a class.