I HATE ARRAYs!

[Anon]

function categories_in ($field, $db) {
global $counter, $cat_array;

$query = "SELECT * FROM X WHERE a ='$field'";
$result = mysql_query($query, $db);
$total_matches  = mysql_num_rows($result);
echo "<b>$field</b> total_matches: $total_matches<br>";
if (!$category){
	echo "error <br>";
}else{
	while ($row=mysql_fetch_array($result)){
		$b = $row["b"];echo "found: $b<br>";
		$c = $row["c"];
		$cat_array[$counter] = $b;
		// or other method $cat_array = array($b);
		$counter ++;
	}
}
echo "Total Counted: $counter<br>";
echo "cat_array[$counter]= $cat_array[$counter] <br>";

[Anon]

Ok, try these magic lines in your for next loop one at a time...

while ($row=mysql_fetch_array($result)){
print array_splice (implode (":", array_keys ($row) ), implode (":", array_values($row));
print "<BR>";
}

Or:

while ($row=mysql_fetch_array($result)){
print "Array keys:".implode(" ",$array_keys($row));
print "<BR>";
print "Array values:".implode(" ",array_values($row));
}

And tell us what you see.

PS, read up on all the array functions on the docs at:
ref.array.html on php documentation trees. Arrays in PHP are easily tamed with a few neat commands that show them their place.

P.s. both of those examples assumed single dimension arrays. You can write some fun functions to explore multi-dimensional arrays, even uneven ones, quickly.