Variable variables?

Clarkey_Boy

Hi,

I have been using php for a LOT of SQL recently. I have several nested while loops, and I need to use the values clarified in the while loops several times throughout a page. Is there any way to create these while loops once and make variable variables out of them?

$x = 0;
while($x <= 3) {
$a$x = $x + 1;
$x++;
}

The idea of this is to make $a0 = 1, $a1 = 2, $a2 = 3, $a3 = 4. I have been tring to do this for ages but have not yet found a way.

Clarkey Boy

Drakla

Straight from my example book I keep for mysqlf for these type of days

<pre>
<?php
	for ($i = 1; $i < 5; $i++)
	{
		${'r' . $i} = $i * 10 . ' chahhh';			// $r1, $r2 etc
		${'XX' . $i*10} = $i * 10 . ' zing!';		// $XX10, $XX20 DOESN'T NEED BRACKETS
		${'YYY' . ($i + 500)} = $i + 500 . ' Noo Noo';// $YYY500, $YYY501 NEED BRACKETS

	$m{$i} = $i * 100 . ' mooolooo';			// acts as $m[$i]

	//$p$i = $ * 1000;	// not poseeeble
}

$vars = get_defined_vars();
	// take out any key with underscores
foreach ($vars as $key => $value)
	if (strpos($key, '_') !== false)
		unset($vars[$key]);

ksort($vars);
print_r($vars);
?>
</pre>

Installer

You really should be using arrays instead of numbered variables, which are, in most cases, a trite newbie hack.

jdorsch

Installer wrote:
You really should be using arrays instead of numbered variables, which are, in most cases, a trite newbie hack.

Exactly, if you start declaring variables like this your code is going to turn into a trainwreck of readability.

Clarkey_Boy

I actually use a mixture of arrays and variables. My entire game is basically based on tables (using an MS Access database. I just want to try out a few different methods before settling for one of them. The variable variables thing is just for declaring variables as values within nested while loops. That way, I don't have to call the same group of while loops several times in one page, I can just use one while loop for the variables (to update the database if a user trains their villagers or purchases / upgrades a building).

Thanks for the advice.

jdorsch

If you need variables like these, and there is no other way, then you can use eval to create these variables

$code = '$a'.$x .' = '.$x+1 ; // if $x = 2 then '$a2 = 3' ;
eval( $code ) ;

I am curious as to exactly how you are doing your updates for your game and how your code works or why this is needed. Are you using objects for each of your entities, for instance a villager object and a building object? If this is some sort of RTS it would be a very good application of OO design patterns.

MarkR

Using "variable variables" is probably a very bad idea, as others have hinted. Use an array instead.

Mark