Parsing Strings

Hi. Before I try and reinvent the wheel, I thought I'd query the list. I want to take this string: thisIsAStringIHave and turn it into: This Is A String I Have Essentially, I want to capitalize the first letter (ucfirst) and then put a space in front of each uppercase letter. I didn't find a PHP function that did this (but maybe I didn't look diligently enough). My idea to accomplish this is to create an array of capital letters. Then iterate through each letter in the string. If a letter in the string matches a letter in the array of capital letters, replace that letter with a space + that letter. Is there a better way than brute-forcing this?? =D Thanks in advance, ~Philip