Alfabetic order error code

Hi all!

I have an alfabetic order code that lists a number of results that looks like this:

<?
$conn = mysql_connect('localhost', 'root', '') or die('ERROR: Unable to connect to database.');
$db = mysql_select_db('nieto') or die('ERROR: Unable to select database.');
$sql = 'SELECT produto FROM produto ORDER BY produto';
$result = mysql_query($sql) or die('ERROR: '.$query.' '.mysql_error());
$letterlinks = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
echo '<a name="top"></a>';
echo '<a href="#number">0-9</a> ';
for ($i = 0; $i < 37; $i++):
echo '<a href="#'.$letterlinks[$i].'">'.$letterlinks[$i].'</a> ';
endfor;
while ($list = mysql_fetch_object($result)):
$letter = strtoupper(substr($list->produto, 0, 1));

if ($prev_row != '0-9' && is_numeric($letter)):
echo '<br /><a name="number"></a><b><u>0-9</u></b> ';
echo '<a href="top"><i>goto top</i></a><br />';
$prev_row = '0-9';
endif;
if ($letter != $prev_row && !is_numeric($letter)):
echo '<br /><a name="'.$letter.'"></a><b><u>'.$letter.'</u></b> ';
echo '<a href="#"><i>top</i></a><br />';
$prev_row = $letter;
endif;
echo $list->produto.'<br />';
endwhile;
?>

I getting 3 errors that I do not understand:

1- Notice: Uninitialized string offset: 36 in c:\programas\easyphp1-8\www\nieto\expe.php on line 10

2-Notice: Undefined variable: prev_row in c:\programas\easyphp1-8\www\nieto\expe.php on line 15

3- I’m getting repeated alphabetic letters. This is perhaps because of Portuguese Special charset:

Example I get:

O
Ontario

Ó
Óntário

And then again

O
Omanel.

Anyone?

Thanks
António

 

this will help you get rid of notices