What is an abstract class in PHP?

Question

What is an abstract class in PHP?

How can it be used?

Answer 1

Abstract Class
1. Contains an abstract method
2. Cannot be directly initialized
3. Cannot create an object of abstract class
4. Only used for inheritance purposes

Abstract Method
1. Cannot contain a body
2. Cannot be defined as private
3. Child classes must define the methods declared in abstract class

Example Code:

abstract class A {
    public function test1() {
        echo 'Hello World';
    }
    abstract protected function f1();
    abstract public function f2();
    protected function test2(){
        echo 'Hello World test';
    }
}

class B extends A {
    public $a = 'India';
    public function f1() {
        echo "F1 Method Call";
    }
    public function f2() {
        echo "F2 Method Call";
    }
}

$b = new B();
echo $b->test1() . "
";
echo $b->a . "
";
echo $b->test2() . "
";
echo $b->f1() . "
";
echo $b->f2() . "
";

Output:

Hello World
India
Hello World test
F1 Method Call
F2 Method Call