Please, teach me the result of this code... result :10101010

Question

<?php

class a{

public $c=5;
public function a(){

echo $this->c;

}
}
class b extends a{
public $c=10;
public function b(){
echo $this->c.$this->a();

}
}
$obj = new b();
$obj->b();
?>

Answer 1

When you create an instance of a, $c = 5, when you create an instance of b, $c = 10. You don't create instance of a in you code, so the value 5 will never be printed. Always remember that in the b class, $c is always equals to 10.
When you create your b object, the be function is called a first time. It print the $c value (your first 10), and call the a function, which is a member of the two classes here. This function only print the $c value, so, as in you b class $c = 10, the a() function prints 10 because it is called in b class where $c = 10. (Second 10)
(Your a() function doesn't return value, but print the $c value, so what you did in the b function is equivalent to do:
echo $this->c;
$this->a(); )
After, you recall the b function and the operation is repeated. ;) (Third and fourth 10)