Tricky array question

Hi there, I have a tricky array question. My app is passing via post a array variable called glacier. Now I am checking for the content of this array. Because there are more of those arrays, I am getting all the names out of a db. How is it possible to get the value and keep the name of the array dynamic? e.g: Array name passed by post is: $glacier // contains e.g. $glacier[0] = testname Array with category names coming out of db is: $category // contains e.g. $category[0] = glacier echo $categories[0]; // returns glacier echo $glacier[0]; // returns testname I tryed $categories[0][0] but it returns only the first letter of glacier (g) Any ideas?? Thanx, Andy