在模型中存储持久值（PHP，MVC）

I am doing a quiz in PHP code igniter. I am trying to have a function that increments the score for every correct answer. At the moment I am not passing anything to the view, and I have this in the controller:

if ($res == true)
        {
        $scoreIncrement = 1;    
        $scoreResult = $this->Starmodel->increment($scoreIncrement);
        var_dump($scoreResult);

If the quess is right, I am passing value 1 to the function increment, and I am dumping the results to see what I get. Here is my function in the model:

var $score; //variable to hold the total score.

function increment($increment){

        $this->score = $this->score + $increment;
        return $this->score;
}

When every I run the application I always get 1 from the var_dump. Is the variable var $score; persistent in the model? Also I am clicking next, which means I am loading the function to display a new message maybe this is resetting the results. How can I have a variable in the model that will hold the current score? Thanks

use session.

You don't seem to be aware of the fact that you invoke a new PHP process with each answer.

PHP start over and over again with each post from a form or request via a href..

Your internal data is re-initialized with each request, hence the result.

Look up session to achieve persistence between requests.

http://php.net/manual/en/features.sessions.php

You could use SESSIONS, or COOKIES to be able to have what is called as "data persistence"

http://php.net/manual/en/features.cookies.php

Setting new cookie
=============================
<?php 
setcookie("name","value",time()+$int);
/*name is your cookie's name
value is cookie's value
$int is time of cookie expires*/
?>

Getting Cookie
=============================
<?php 
echo $_COOKIE["your cookie name"];
?>

you can also put the current score in a hidden form field

// in your view form 
echo form_hidden('currentscore',$this->score); 

then pick up the value after form submit

// pass to your method to increase the score
$currentscore = $this->input->post( 'currentscore') ; 

$score = $currentscore + 1 ; 

opinion: using $this-> is really powerful but it can get unwieldy. if you need to pass a value to a method in a model, consider just doing it explicitly.

function incrementScore($increment,$score){

        $scoretotal = $increment + $score;
        return $scoretotal;
}