Default checked checkboxes undefined in php - forms

Question

I am having trouble with checkboxes. What I am doing is displaying a list of checkboxes, if previously checked they will show the check mark, then you submit them and another php should recognize which were checked and which weren't. My script works fine for boxes previously unchecked, if you check them the action php recognizes it, but for boxes already checked I get Notice - undefined variable - for the boxes (even if unchecked/checked again). I really can't seem to find my way around this.
My code is
$ind=0; //counting variable
//generating checkboxes from an xml
foreach($xml as $checkbox)
{
$checks=$xml->checkbox[$ind]->active; //the active tag has a 0 or 1 stored.
echo "Activate ".$ind; // shows activate 0, activate 1, etc...
echo "<form name='checkb' action='show.php' method='post'>
echo "<input type='checkbox' name='checks[]' class='act' value='".$ind."'";
if($checks==0){ echo ">";} else{echo " checked ='checked'>";}
echo "<input type='hidden' name='ind' value=".$ind.">";
$ind=$ind+1;
echo "<input type='submit' name='sub' value='Submit'/> </form>"; }
On my action php I have
$chks = $_POST['checks'];
$N = count($chks);
echo("Active checkboxes ");
for($i=0; $i < $N; $i++)
{
echo($chks[$i] . " ");}
All this worked well until I decided to show if the boxes had been previously checked. So I guess the question is, why won't php recognize checked=checked as a true value? Or is there any other way to do this?
Thanks!

Answer 1

Seems like a lot of issues here.
Why are you outputting a form for each checkbox?
Where is your submit for the form?
You need a space in front of checked='checked' where you echo it out - echo " checked='checked'>"
If you move form output out of the loop, you will need to add your incremented value to the hidden input name property as well (or make it an array like checks, otherwise you will
only get one value for the field.

Answer 2

My attempt to try and clean it up a little.
$ind = 0;
echo "<form name='checkb' action='show.php' method='post'>";
foreach($xml as $checkbox){
echo "Activate $ind";
echo "<input type='checkbox' name='checks[]' class='act' value='$ind' ".(($checks == 0) ? " />" : " checked='checked' />";
echo "<input type='hidden' name='ind_$ind' value='$ind' />";
$ind++
}
echo "</form>";
Notice, like Mike said before that checked='checked' has the space before so that there is seperation between components. Also, your hidden elements all had the same names, so I added the $ind quantifier.
Hope this helps.