Examples of using PHP class constants

class Foo{
const con_var="The value of a constant attribute cannot be modified";
public function method_a(){
echo (self::con_var);
 }
}
echo(Foo::con_var);
$myFoo=new Foo();
echo ($myFoo->method_a());
?>

Note: Constant attributes cannot be accessed using objects, but can only be accessed using classes. Within the class body, you can use "self::constant name", and outside the class body, you can use "class name::constant name".

For information on PHP constants, you can also refer to the following articles: php variables and constants php constants Define and use php constants Learn to understand the usage of constants in php