Final keyword +const keyword

Final keyword

1. If we want a class to not be inherited by other classes (perhaps because of security considerations), you can use final.

Examples

<?    Final class a{}     class extends a{}; // will error    Echo "OK";? >

2. If we want a method, such as a method for calculating personal income tax, that cannot be overridden by a subclass, you can use final to modify the method.

Examples

<?PHPclassa{Final  Public functionGetrate ($salary){    return $salary*0.08;}} classBextendsa{//Unable to overwrite the Getrate method of the parent class    /*Public function Getrate ($sal) {return $sal *0.01;} */}    $b=NewB (); Echo $b->getrate (100);?>

The 3.final keyword cannot be modified to a property.

const keyword

The basic usage is:

Class a{

Const constant NAME = assigned initial value;

}

Interface interface Name {

Const constant NAME = assigned initial value;

}

Note: Constants are public

Examples

<? PHP     class a{    const tax_tate=0.08;      Public function paytax ($va 1) {    return$va 1*a::tax_tate;}}     $a=new  A ();     Echo $a->pay tax (+);? >

Final keyword +const keyword