fwrite()
fwrite() is usually used for local files, but depends. If you're talking about straight ansi C using stdio.h, then no, probably not. You could if you mapped a NFS share or something like that, but if you already have that type of access remotely, then I'm sure there's an easier way to do whatever it is you're trying to do. There's numerous c libs that support remote fwrites over various protocols, such as cURL and GASS.
Most scriptable languages have a friendlier approach to fwrite, particularly php. It support numerous types of remote connections to a server that could accomodate this, but again you'd need some type of pre existing link to the server (ftp, nfs, etc, or something along those lines, but again, probably an easier way to do whatever it is you're trying to do).
As for the PUT comment, I assume you mean an HTTP PUT, and yes that can work, but the server would have to be configured to support PUTs to begin with. Most don't (nor should they). Various httpd's have weaknesses in this regard, particularly older ones, but you can read about proper HTTP PUT's from head to toe at here for apache and here for IIS.
HTH