void setbuf( FILE *stream, char *buf )

	- prototype in stdio.h

	- causes "buf" to be used for I/O buffering instead of the
	  automatically allocated buffer, and are used after given
	  stream is opened
	- if "buf" is NULL, I/O is unbuffered
	- no I/O to the file should occur after opening file until
	  buffering is set

	- see	setvbuf()