<?php

class BankAccount
{
    private static $nextAccNumber = 1;

    private $number;
    private $balance;

    public function __construct()
    {
        $this->number = self::$nextAccNumber;
        $this->balance = 0;

        self::$nextAccNumber++;
    }

    function getNumber()
    {
        return $this->number;
    }

    function getBalance()
    {
        return $this->balance;
    }

    public function depositCash($amount)
    {
        if (!is_numeric($amount) || $amount <= 0) {
            return false;
        }
        $this->balance += $amount;
    }

    public function withdrawCash($amount)
    {
        if (!is_numeric($amount) || $amount < 0) {
            return false;
        }

        $rest = $this->balance - $amount;

        if ($rest < 0) {
            return $amount;
        }

        $this->balance = $rest;
        return $amount;
    }

    public function printInfo()
    {
        echo "ID konta: " . $this->number . ", saldo: " . $this->balance . "<br>";
    }

}

$user1 = new BankAccount();
$user2 = new BankAccount();
$user3 = new BankAccount();
$user4 = new BankAccount();
$user5 = new BankAccount();


var_dump($user3);
var_dump($user5);
var_dump($user1);