For historical reasons, the type of the C data structure that represents
a stream is called
FILE rather than “stream”. Since most of
the library functions deal with objects of type
FILE *, sometimes
the term file pointer is also used to mean “stream”. This leads
to unfortunate confusion over terminology in many books on C. This
manual, however, is careful to use the terms “file” and “stream”
only in the technical sense.
FILE type is declared in the header file stdio.h.
This is the data type used to represent stream objects. A
object holds all of the internal state information about the connection
to the associated file, including such things as the file position
indicator and buffering information. Each stream also has error and
end-of-file status indicators that can be tested with the
feof functions; see EOF and Errors.
FILE objects are allocated and managed internally by the
input/output library functions. Don’t try to create your own objects of
FILE; let the library do it. Your programs should
deal only with pointers to these objects (that is,
FILE * values)
rather than the objects themselves.