Subtraction operator not working!!

[dcr33]

Hi
I am trying to subtract a id from a roll number from a database. But the subtraction is not occurring !!
This is my code :

echo"
            <TR>
            <TD>$c</TD>
            <TD>$row[name]</TD>
            <TD>$row[roll]-$row[id]</TD>
            <TD><A HREF='1.php?page=$_GET[page]&upd=$row[id]'>UPDATE<A></TD>
            </TR>"; 

I am trying various ways like -

"$row[roll]"-"$row[id]" 

OR
like this :

"$row[roll]\"-\"$row[id]\" 

etc etc. but none is working.
Please can anyone tell me how to do the subtraction between row[roll] and row[id]??

[djr33]

Don't put it in quotes. It's a good idea to not put quotes around your variables anyway. Plus, it shouldn't work in quotes when you're using array keys in the []s.

echo"
            <TR>
            <TD>".$c."</TD>
            <TD>".$row[name]."</TD>
            <TD>".($row[roll]-$row[id])."</TD>
            <TD><A HREF='1.php?page=".$_GET[page]."&upd=".$row[id]."'>UPDATE<A></TD>
            </TR>"; 

I also put the subtraction operation in parentheses to avoid any potential ambiguities. (I think PHP first joins with . then subtracts with -, which would give you the wrong result obviously.)