Trying to stack values with PHP - php

Question

Im currently trying to make a little dice game in php. Right now Im trying to make a "currentscore" where all the points from a rand(1,6) are stacked into a single variable.
Here is the class Im doing this in:
<?php
class CDice {
public $roll;
public $currentscore;
public function Roll()
{
$this->roll = rand(1,6);
return $this->roll;
}
public function currentScore()
{
$this->currentscore += $this->roll;
return $this->currentscore;
}
}
I don't under stand why $this->currentscore += $this->roll; doesn't work.

Answer 1

You do realise that at the end of execution of this class no values are kept right? If you wish to transfer over this data to the next page render, you should use PHP sessions.
<?php
class CDice {
public $roll;
public $currentscore = 0;
public function Roll(){
$this->roll = rand(1,6);
$this->currentscore += $this->roll;
return $this->roll;
}
public function currentScore(){
return $this->currentscore;
}
public function __construct(){
if(session_status() == PHP_SESSION_ACTIVE){
$this->currentscore = isset($_SESSION['dice.score']) ? $_SESSION['dice.score'] ? 0;
# In PHP 7.0
# $this->currentscore = $_SESSION['dice.score'] ?? 0;
} else {
echo 'session has not been initiated';
}
}
}
session_start();
$tmp = new CDice();
echo $tmp->Roll();
echo $tmp->Roll();
echo $tmp->currentScore();
?>
Also not assigning an "initalial" value to a variable before trying to add things to it with +=, -=, etc causes PHP to throw a warning.