Explode string by one or more spaces or tabs

How can I explode a string by one or more spaces or tabs?

Example:
A      B      C      D

To separate by tabs:

$comp = preg_split("/[\t]/", $var);

To separate by spaces/tabs/newlines:

$comp = preg_split('/\s+/', $var);

To seperate by spaces alone:

$comp = preg_split('/ +/', $var);