Multiple explode characters with comma and - (hyphen)

... or if you don't like regexes and you still want to explode stuff, you could replace multiple characters with just one character before your explosion:

$keywords = explode("-", str_replace(array("\n", "\t", "\r", "\a", ",", "-"), "-", 
  "my string\nIt contains text.\rAnd several\ntypes of new-lines.\tAnd tabs."));
var_dump($keywords);

This blows into:

array(6) {
  [0]=>
  string(9) "my string"
  [1]=>
  string(17) "It contains text."
  [2]=>
  string(11) "And several"
  [3]=>
  string(12) "types of new"
  [4]=>
  string(6) "lines."
  [5]=>
  string(9) "And tabs."
}