How do you store information temporarily without the use of an config?

How do you store information temporarily without the use of an config? Do you have to use a private?
Ex:

PHP:

Private $example = false;


When you change it with something like umm,

PHP:

$this->example = true;


Will this work also?

PHP:

Private $example = 0;


When you change it with something like umm,

PHP:

$this->example = 1;
//and will this work also?
$this->example = 0; + $a;
$a = 1;


S

So I have to change it to public?

Wait so my question is right?

@Legomite if you want to use a variable in any function of your plugin, you need to declare it
at the begining of the plugin, with the private $api;

PHP:

class PLUGIN implements Plugin
{
    private $api;
    private $exemple;

    public function __construct(ServerAPI $api, $server = false)
    {
        $this->api = $api;
        $this->exemple = array();
    }
...

you can easy store informations in $exemple but this variable ll be deleted if you stop de server.
dont forget to unset() if it contain useless value !

That's what I want it to do

PHP:

public function UnsetArray($data){
    if($key = in_array("$data", $this->example)){
        unset($this->example[$key]);
    }
}

^^^^^ This will let you unset arrays

PHP:

public function SetArray($data){
    array_push($this->example, "$data");
}

^^^^^ This will let you set arrays

PHP:

public function CreateArray($data){
    $this->example = array();
}

^^^^^ This will let you create arrays @Legomite

Wow! this would have been really helpful, I had no idea you could do the public variable thing, I made a CTF plugin and I used the config to link all the functions together this is ridiculously helpful thanks.