PHP convert string to array -

How do I convert a string to an array? For example, I have this string:

  $ str = 'abcdef';  

And I want to:

  array (6) {[0] => String (1) "a" [1] = & gt; String (1) "B" [2] = & gt; String (1) "c" [3] = & gt; String (1) "D" [4] = & gt; String (1) "E" [5] = & gt; Use strings (1) "f"}  

str_split