Attempts to rename oldname to newname.
Palauttaa TRUE onnistuessaan, muutoin FALSE.
Huomaa: Prior to PHP 4.3.3, rename() could not rename files across partitions on *nix based systems.
Huomaa: As of PHP 5.0.0 rename() can also be used with some URL wrappers. Refer to Liite J for a listing of which wrappers support rename().
Huomaa: The wrapper used in oldname MUST match the wrapper used in newname.
Huomaa: The context parameter was added as of PHP 5.0.0.
See also copy(), unlink(), and move_uploaded_file().