I wonder what's the historical use of microtime() returning a string? is the string actually useful at some point? i see code every where just get back the value and constructing it as a float. why not returning it as a float when microtime() was first written?
microtime() has always returned the same. Only the "get as float" option was added later, but it's optional if you set the first argument to "true". www.php.net/microtime