Vector calculations class oop php - php

Question

I'm learning php oop and seems like i still do not understand of how some things work as my code, which, imo, looks properly doesn't work and returns few errors. This is the code:
<?php
class Vector {
private $x;
private $y;
public function __construct($x, $y) {
if (is_nan($x) || is_nan($y)) {
$this->x = 0 && $this->y = 0;
} else {
$this->set($x, $y);
}
}
public function __destruct() {
var_dump($x, $y);
}
public function setx($x) {
if (is_numeric($x)) {
$this->x;
}
}
public function sety($y) {
if (is_numeric($y)) {
$this->y;
}
}
public function retLength() {
return $x;
}
public function addVector() {
$sum=$x+$y;
}
public function dotProduct() {
$dot_product = array_sum(array_map(function($x,$y) { return $x*$y; }, $array1, $array2));
}
}
$wekt= new Vector($x, $y);
echo $wekt->addVector(5,7);
Errors i get are: undefined variables "x" and "y" on line 42 (which is $wekt= new Vector($x, $y); ) and "Call to undefined method Vector::set()".
Specification for this class is:
two private attributes $x and $y (seems to be ok)
constructor receives $x and $y and on receive checks if these are numbers. Constructor is supposed to output message about just created vector.
I do not understand much all this constructor and probably this is one of reasons why this code doesn't work as it is intended to.
destructor is supposed to output info about destroyed object.
there should be available functions to change values of $x and $y
there should be available function to return $x
two more functions: one outputting sum of two vectors, second function supposed to output scalar product which takes as value a number.

Answer 1

There are two things in your code going wrong. See the following code:
class Vector {}
$wekt= new Vector($x, $y);
echo $wekt->addVector(5,7);
Where are $x and $y defined? This is the main reason you are getting the error. You class has a different scope then the global scope, meaning everything you define there is only accessible by $wekt-> as $wekt is defined in the global scope.
Now the second thing is addVector():
echo $wekt->addVector(5,7);
You ask to echo the return of this method, yet no return is defined in that function. Secondly where is the $x and $y defined within the scope of that function?
Change it to something like:
class Vector {
private $list = [];
public function addVector($x, $y) {
$this->list[] = new Vector($x, $y);
return $x + $y;
}
}