How do I return words from string (1) which starts with char and ends with space and (2) starts with space and ends with space? : <pre>(1) which starts with char and ends with space ? and 
(2) starts with space and ends with space ?

For example:
$string = "I am using php regular expressions";

Output:
$out = {"I", "am", "using", "php", "regular"}; #expected output

Any suggesions. </pre>
