Re: Public in Classes

Ben Stones schreef:

Hi, I have this piece of code that I have created: class userQueries {

    public function numberUsers() {
        $get_users=mysql_query("SELECT * FROM users WHERE online <

NOW()") or exit("../includes/error.php");

    }

} class usersOnline extends userQueries {

    public function usersOnline() {
        echo mysql_num_rows($this->numberUsers);
    }

} How do I request specific methods in other classes? The error that comes up is: mysql_num_rows(): supplied argument is not a valid MySQL result resource which is somewhat expected as $this only refers to the variables and there are no variables called numberUsers. Cheers!

1. don't double post, a bit of patience is in order. 2. this has nothing to do with public/private methods. 3. use braces to call a method ... methods are not variables. 4. you can't pass an include file to exit and expect it to run that file (it will just echo out the string you gave it) 5. the 'foo() or exit()' error handling strategy is rather crap (imho) ... you could do it gracefully instead of just killing the script. 6. I doubt whether "online < NOW()" will give you the result your looking for class userQueries {

    public function numberUsers($where = "1") {
        $r = mysql_query("SELECT * FROM users WHERE $where") or $this->killMe();

$n = mysql_num_rows($r); mysql_free_result($r); return $n;

    }

    protected function killMe()
    {

include "../includes/error.php"; exit(1);

    }

} class usersOnline extends userQueries {

    public function usersOnline() {
        return $this->numberUsers("online < NOW()");
    }

}

2008/9/21 Jochem Maas <jochem@iamjochem.com>

Ben Stones schreef: Hi,

Just started with object oriented programming and glad I have come across it, just need a few things clearing up. When I make a variable or method public, does this mean that it can be used outside of classes, for instance in other classes or as well as instantiating classes? So if I made it private, it wouldn't be able to be instantiated or extended in other classes, am I right? I have never added public when I am creating methods so I presume its already set as default if you don't add it? Hope you can understand my question.

yes, and the answer nearly always lies in trying it out, run this (and if/when you hit a fatal error, comment the offending line and run it again): <?php class Test {

       public          $a = "A";
       protected       $b = "B";
       private         $c = "C";

       function tryme()
       {
               echo $this->a, "\n";
               echo $this->b, "\n";
               echo $this->c, "\n";
               echo $this->d, "\n";
       }

} class TestTwo {

       function tryme()
       {
               echo $this->a, "\n";
               echo $this->b, "\n";
               echo $this->c, "\n";
               echo $this->d, "\n";
       }

} $t1 = new Test; $t2 = new TestTwo; $t1->tryme(); echo $t1->a, "\n"; echo $t1->b, "\n"; echo $t1->c, "\n"; echo $t1->d, "\n"; $t2->tryme(); echo $t2->a, "\n"; echo $t2->b, "\n"; echo $t2->c, "\n"; echo $t2->d, "\n"; ?> Cheers.