[SOLVED] OOP PHP 4-5 Problem

[V34]

It's actually the same problem as last time, but this time I got more specific with my problem.

It seems like the Health variable don't want to change of some reason.

 

I'm still using PHP 4.

<?php
class Person {
  var $health = 100;

  function attack($perAtt) {
   if ($man->health > 0 && $woman->health > 0) {
   $perAtt->health = $perAtt->health - 25;
   }
  }

}

$man = new Person();
$woman = new Person();

while ($man->health > 0 && $woman->health > 0) {
$man->attack($woman);
$woman->attack($man);
echo "$man->health | $woman->health<hr>";
}

echo $man->health." || ".$woman->health;

?> 

 

It echo's 100 | 100 all the time, but if I change my PHP version from 4 to 5 there's no problem at all.

Now this is not a solution. I want to know how I change the variable, thanks.

 

- Jesper Eiby

[448191]

This makes no sense:

 

$man->health > 0 && $woman->health > 0

 

Where are these $man and $woman variables coming from?

[V34]

$man = new Person();

$woman = new Person();

 

[448191]

Well duh, but those are not in the same scope as that line. 

[V34]

<?php
class Person {
		var $health = 100;

		function attack($perAtt) {
		 if ($this->health > 0 && $perAtt->health > 0) {
		  $perAtt->health = $perAtt->health - 25;
		 }
		}

}

$man = new Person();
$woman = new Person();

while ($man->health > 0 && $woman->health > 0) {
$man->attack($woman);
$woman->attack($man);
echo $man->health." | ".$woman->health."<hr>";
}

echo $man->health." || ".$woman->health;

?>

 

My bad, but still this improvement didn't seem to work.

[448191]

Try using &new.

[V34]

Thanks for the help, but the &new didn't seem to have any effect at all.

 

I've also tryed putting global $health; in top of the attack() function. Again with no luck

 

 

[448191]

<?php
class Person {
var $health = 100;

function attack($perAtt) {
	if ($this->health > 0 && $perAtt->health > 0) {
		$perAtt->health = $perAtt->health - 25;
	}
}
}

$man = &new Person();
$woman = &new Person();

while ($man->health > 0 && $woman->health > 0) {
$man->attack($woman);
$woman->attack($man);
echo $man->health." | ".$woman->health."<hr>";
}
echo $man->health." || ".$woman->health;
?>

 

It outputs this on php5:

 

75 | 75

50 | 50

25 | 25

25 | 0

25 || 0

 

I don't see any reason why it should output anything different on php4.

[V34]

Neither do I, but if change my PHP version from 5 to 4, it will print 100 | 100 infinity.

[448191]

What do you mean by 'infinity'?

 

Edit: please show the EXACT output.

[V34]

100 | 100

100 | 100

100 | 100

100 | 100

 

It never ends, it keep loading and continuing  100 | 100.

 

 

[448191]

I see. So you get stuck in a loop because Person::health never decrements.

[448191]

Try this:

 

while ($man->health > 0 && $woman->health > 0) {
$man->attack(&$woman);
$woman->attack(&$man);
echo $man->health." | ".$woman->health."<hr>";
}

[V34]

Yes exactly.

But if I change $perAtt->health = $perAtt->health - 25; to $this->health = $this->health - 25;

It has no problem working, but then they're attacking them self.

 

Again thanks for you help.

[448191]

The above post should work. It's basic stuff, actually, but I've been off php4 for so long that I overlooked it. php4 makes copies of objects whedn you pass them, so you have to pass by reference to avoid that a copy is made (to avoid $health being set to 100 every time you attack()).

[V34]

Thanks alot! That worked!

And it also worked on PHP 5.

 

Could you explain what the & does, or do you reefer me to Google?

 

EDIT: Ahh, thanks a lot for all your help! I'm quite new in OOP but I've been programming PHP for 2years.

[448191]

OOP on php4 is a bit tweaky. The golden rule is to use the 'reference operator' (&) whenever you pass an object, unless you intend to clone it.