Returns TRUE if the file or directory specified by filename exists; FALSE otherwise.
On windows, use //computername/share/filename or \\computername\share\filename to check files on network shares.
備注:此函數的結果會被快取。詳細資訊請參考 clearstatcache()。
心得:As of PHP 5.0.0 this function can also be used with some URL wrappers. Refer to 附錄 L for a listing of which wrappers support stat() family of functionality.
See also is_readable(), is_writable(), is_file() and file().