[RESOLVED] Variables within variable names

Staggy11

Would it be possible to create a variable that had the value of another variable within its name. For example, instead of having

$object1 = mysql_fetch_object($result1);
$object2 = mysql_fetch_object($result2);
$object3 = mysql_fetch_object($result3);
$object4 = mysql_fetch_object($result4);
$object5 = mysql_fetch_object($result5);
$object6 = mysql_fetch_object($result6);
$object7 = mysql_fetch_object($result7);
$object8 = mysql_fetch_object($result8);
$object9 = mysql_fetch_object($result9);

could you have something like

$i = 1;
whilst ($i<=9)
{
$object.'$i'. = mysql_fetch_object($result.'$i'.);
$i =+ 1;
}

If it isn't possible, can anyone recommend a way of doing 9 mysql_queries, and then fetching the object of those queries, and freeing the 9 results once you have got 9 different variables with the information in?

Kudose

for($i=1;$i<=9;$i++)
  $object{$i} = mysql_fetch_object($result{$i});

That should work.

laserlight

It is possible, of course, but you are better of using arrays.

for ($i = 1; i <= 9; ++$i)
{
	$object[$i] = mysql_fetch_object($result . '$i');
}

If you really have to use variable variables:

for ($i = 1; i <= 9; ++$i)
{
	${'object' . $i} = mysql_fetch_object($result . '$i');
}

Oh, and why have so many result sets?

Staggy11

Thanks for the response. I need to do 9 of everythig, because I am making a small map for a game. it would be a 3 by 3 grid, with your position in the middle. Each grid in the entire map has a row in a database, and I eed to get the information for the relevant cells to draw the map.

bradgrafelman

Well, this means you'll have that many resources connected to MySQL instead of just one.

Just use one and build an array...

Staggy11

I am now using arrays and 'while' functions. Thanks for the advice.

However, there is still one problem. My code now looks like this:

<?
session_start();
include 'db.php';
$playerx == $_POST['x'];
$playery == $_POST["y"];

$x = array (
"1" => $playerx-1, 
"2" => $playerx,
"3" => $playerx+1,
"4" => $playerx-1,
"5" => $playerx,
"6" => $playerx+1,
"7" => $playerx-1,
"8" => $playerx,
"9" => $playerx+1,
);

$y = array (
"1" => $playery-1, 
"2" => $playery-1,
"3" => $playery-1,
"4" => $playery,
"5" => $playery,
"6" => $playery,
"7" => $playery+1,
"8" => $playery+1,
"9" => $playery+1,
);

$result = array();
$i = 1;
while ($i <= 9)
{
$result[$i] = mysql_query("SELECT * FROM map WHERE x = '$x[$i]' AND y = '$y[$i]'");
$i += 1;
}

$i = 1;
while ($i <= 9)
{
    $object[$i] = mysql_fetch_object($result[$i]);
    $i += 1;
} 

$i = 1;
while ($i <= 9)
{
mysql_free_result($result[$i]);
$i += 1;
}
?>
<TABLE BORDER>
	        <TR>
	<? $i = 0;
	   $u = 1;



    while ($i < 3)
	{ 

	?>
	        <TD><form action="map.php" method="post">
                       <input type=hidden name="x" value="<? $object[$u]->x ; ?>">
                       <input type=hidden name="y" value="<? $object[$u]->y ; ?>">
                       <input type="submit" value="<? echo $object[$u]->name ; ?>">
                       </form>
                   </TD> 
            <?   
    $u += 1; 
$i += 1;  
}//end of making new cell  

$i = 0;
?> </TR><TR>
<?
   while ($i < 3)
	{ 

	?>
	        <TD><form action="map.php" method="post">
                       <input type=hidden name="x" value="<? $object[$u]->x ; ?>">
                       <input type=hidden name="y" value="<? $object[$u]->y ; ?>">
                       <input type="submit" value="<? echo $object[$u]->name ; ?>">
                       </form>
                   </TD> 
            <?   
$u += 1;  

	$i += 1;  

		}//end of making new cell  

	$i = 0;

?> </TR><TR>
<?
   while ($i < 3)
	{ 

	?>
	        <TD><form action="map.php" method="post">
                       <input type=hidden name="x" value="<? $object[$u]->x ; ?>">
                       <input type=hidden name="y" value="<? $object[$u]->y ; ?>">
                       <input type="submit" value="<? echo $object[$u]->name ; ?>">
                       </form>
                   </TD> 

            <?   

$u += 1; 
	$i += 1;  

	}//end of making new cell  


?> 

</TR>
</TABLE>

However, when I click on one of the buttons, it does nothing. Can anyone work out what is wrong? The page can be found here: http://staggy11.byethost3.com/map.php

laserlight

However, when I click on one of the buttons, it does nothing.

View source and find out.

By the way, the first part of your script can be simplified to:

<?php
session_start();
include 'db.php';
$playerx == $_POST['x'];
$playery == $_POST["y"];

$x = array (
	"1" => $playerx-1,
	"2" => $playerx,
	"3" => $playerx+1,
	"4" => $playerx-1,
	"5" => $playerx,
	"6" => $playerx+1,
	"7" => $playerx-1,
	"8" => $playerx,
	"9" => $playerx+1,
);

$y = array (
	"1" => $playery-1,
	"2" => $playery-1,
	"3" => $playery-1,
	"4" => $playery,
	"5" => $playery,
	"6" => $playery,
	"7" => $playery+1,
	"8" => $playery+1,
	"9" => $playery+1,
);

$rows = array();
for ($i = 1; $i <= 9; ++$i)
{
	$result = mysql_query("SELECT * FROM map WHERE x = '$x[$i]' AND y = '$y[$i]'");
	$rows[$i] = mysql_fetch_assoc($result);
	mysql_free_result($result);
}
?>

bradgrafelman

This:

$playerx == $_POST['x']; 
$playery == $_POST["y"];

is incorrect.

Looking on the man page [man]operators.logical[/man] we see that '==' means the same as a logical And, so == will always return either true or false (1 or 0).

What you need to do, however, is give the variable a value. Looking on the man page [man]operators.string[/man], we see that a single equal sign does this.

EDIT: Also, if you expect these two variables to be integers... be careful! You should always always ALWAYS sanitize user input before you use it. In this case, you could use a function like [man]intval/man to get the value for the variables.

Don't trust ANYTHING that can be manipulated by user input. Even $_SERVER['PHP_SELF'] is vulnerable to user input.

Staggy11

Thanks for all the support, it now works. The POST part looks like this:

if (($_POST[x])||($_POST[y]))
	{
$playerx = $_POST[x];
$playery = $_POST[y];	
}
else {
$playerx = 2;
$playery = 2;
}

Laserlight I took your suggestion, and I realised that I needed

<? echo $object[$u]->x ; ?>

instead of

<? $object[$u]->x ; ?>

It now works fully, and I will take your advice to use intval(). Thanks!

bradgrafelman

Don't forget, array indeces are strings, so you need quotes around them. $_POST['x'] and such.