ANDs Error in Authentication script

Anon

I am using the code below to create an authentication system. Ie each group of users has a number (1,2,4,8,16,32 etc...) each page then has a number value dependent on who can access that page ie index = 3 (2+1) and accounts = 28 (16+8+4).

I store these values in a DB and they are seleted by a multiple List menu, my problem is trying to edit using the list menu. I want the page to open up, select the record for that page, then show a list box with all the user groups, and the ones that can access the page are selected. Here is my code, but it only selects the 1st 2 always, regardless of the value.

$sql = "SELECT * from userlevels
";
#execute the query
$users = mysql_query($sql)
or die("Error!");

<select name="levels[]" size="<? echo "$numusers"; ?>" multiple>
<?
#now we'll loop thorugh and isert labels and values
while ($row = mysql_fetch_array($users)) {
$ulabel = $row['groupname'];
$ulevel = $row['grouplevel'];
echo " <option value=\"$ulevel\" ";

for($i=0;pow(2,$i) <= $levreq;$i++) {
if($levreq & pow(2,$i)) {
if($i == $ulevel){
echo "selected";
}
}
}

echo ">$ulabel</option>
";
}

$levreq is the Level Required and
$ulevel is the field in the user groups DB that contains the level value

Any help would be appreciated

Marcus

Anon

Changing your "for" loop to this should do the trick:

// start at 1, since 0 is not a valid group
for($i = 1; $i <= $levreq; $i *= 2) {
    if(($levreq & $i) && ($ulevel & $i)) {
        echo "selected";
    }
}