string convert to array

I want split a 开发者_如何学编程string to array by Case Sensitivity. like

$str = 'CreateTechBook' 

convert to

 array('Create','Tech', 'Book')

---

function splitCamelCase($str) {
    return preg_split('/(?<=\\w)(?=[A-Z])/', $str);
}

---

 preg_replace('/([a-z0-9])?([A-Z])/','$1 $2 $3',$string);