Replacing first character in a string

Hi there, I wonder if anyone can help me? I have a string something like this: ",.00109863,.00219725,.00329588.... and so on....". If the *first character* in the string is a comma (as in the case above) then I want to replace it with "0,", but I cannot find a way to do it. E.g. say the above string is called $rawPOINTS, what would be in the body of the if loop below to replace the comma? if ($rawPOINTS[0] == ",") { // hmmmm.... } I can think of a few long winded ways of do it, but are there any "one liner" string manipulation functions I can use? I shall look into regular expressions, but if anyone could tell me the solution I'd appreciate it ;-) - Thanks, Lee