search for a string?

[David Broadwell (remove spam.)]

> 
>     OldString = File.read() + OldString
> 
>     I perfer, though: OldString = "%s %s" % (File.read(),OldString)
> 
The second once certianly looks more .. programmer. Now which is more
efficent? (faced with to apparenly equal choices) and why?