Code Structure/Errors

I'm just curious if there's a way to restructure my code so as to avoid getting "Undefined Variable" errors. I keep getting them and I know they're nothing to worry about for the most part, I'd like to get rid of them without turning off error reporting if possible. In the following code, I get an undefined variable error for $i and for $last_name, is there anything I can do to actually define them? $last_name is a variable produced by my MySQL query, $i is just a counter: while ($row = mysql_fetch_array($result)) { extract($row); $i++; if($i=="1") { print "<tr>\n"; } if($last_name) { <print stuff here> } else { <print other stuff> } ... if ($i=="5") { print "</tr>\n"; $i=0; } } Thanks! Jason Soza