Returns the size of the file in bytes, or FALSE (and generates an error
of level E_WARNING) in case of an error.
Note:
Because PHP's integer type is signed and many platforms use 32bit integers,
filesize() may return unexpected results for files which
are larger than 2GB. For files between 2GB and 4GB in size this can usually
be overcome by using sprintf("%u", filesize($file)).
Note: The results of this
function are cached. See clearstatcache() for
more details.
Tip
As of PHP 5.0.0, this function
can also be used with some URL wrappers. Refer to
List of Supported Protocols/Wrappers for a listing of which wrappers support
stat() family of functionality.