Unlock the power of PHP class constants with practical examples. Master efficient data encapsulation and code organization for streamlined web development.
Class constants can be useful if you need to define some constant data within a class.
A class constant is declared inside a class with the const
keyword.
A constant cannot be changed once it is declared.
Class constants are case-sensitive. However, it is recommended to name the constants in all uppercase letters.
We can access a constant from outside the class by using the class name followed by the scope resolution operator (::
) followed by the constant name, like here:
<?php
class Goodbye {
const LEAVING_MESSAGE = "Thank you for visiting W3Schools.com!";
}
echo Goodbye::LEAVING_MESSAGE;
?>
Or, we can access a constant from inside the class by using the self
keyword followed by the scope resolution operator (::
) followed by the constant name, like here:
<?php
class Goodbye {
const LEAVING_MESSAGE = "Thank you for visiting W3Schools.com!";
public function byebye() {
echo self::LEAVING_MESSAGE;
}
}
$goodbye = new Goodbye();
$goodbye->byebye();
?>
#php