Converting category Id's and Names to an array

[Studebaker]

I am working on a script where a database containing link Id's and names is queried, the result(s) placed into an array and then formatted to display as a list. I am getting some errors regarding the "foreach" loop. The error states that there is an invalid argument in the "foreach" loop. Could anybody help me out?

Here is the code:
(The problem loop appears in the "display_categories" function.)

// Returns an array of categories within the system
function get_categories()
{
	// query database for a list of the categories/page links
	$conn = db_connect();
	$query = 'select catid, catname
			  from Categories';
	$result = @mysql_query($query);

if (!$result)
	return false;

$num_cats = @mysql_num_rows($result);

if ($num_cats == 0)
	return false;

$result = db_result_to_array($result);

return $result;
}

// Function that converts a MySQL result identifier into an array of results
function db_result_to_array($result)
{
	$res_array = array();

for ($count=0; $row = mysql_fetch_array($result); $count++)
	$res_array[$count] = $row;

return $res_array;

}

// This function displays an array of categories as a list of links to those categories
function display_categories($cat_array)
{
	if (is_array($cat_array))
	{
		return false;
	}
	echo '<ul>';

foreach ($cat_array as $row)
{
	$url = 'show_link.php?linkid='.($row['catid']);
	$title = $row['catname'];
	echo '<li>';
	do_html_url($url, $title);
	echo'</li>';
}
echo '</ul>';
}