fgetwc (The Red Hat newlib C Library)

#include <stdio.h>
#include <wchar.h>
wint_t fgetwc(FILE *fp);

#define _GNU_SOURCE
#include <stdio.h>
#include <wchar.h>
wint_t fgetwc_unlocked(FILE *fp);

#include <stdio.h>
#include <wchar.h>
wint_t _fgetwc_r(struct _reent *ptr, FILE *fp);

#include <stdio.h>
#include <wchar.h>
wint_t _fgetwc_unlocked_r(struct _reent *ptr, FILE *fp);

#include <stdio.h>
#include <wchar.h>
wint_t getwc(FILE *fp);

#define _GNU_SOURCE
#include <stdio.h>
#include <wchar.h>
wint_t getwc_unlocked(FILE *fp);

#include <stdio.h>
#include <wchar.h>
wint_t _getwc_r(struct _reent *ptr, FILE *fp);

#include <stdio.h>
#include <wchar.h>
wint_t _getwc_unlocked_r(struct _reent *ptr, FILE *fp);

Description
Use fgetwc to get the next wide character from the file or stream identified by fp. As a side effect, fgetwc advances the file’s current position indicator.

fgetwc_unlocked is a non-thread-safe version of fgetwc. fgetwc_unlocked may only safely be used within a scope protected by flockfile() (or ftrylockfile()) and funlockfile(). This function may safely be used in a multi-threaded program if and only if they are called while the invoking thread owns the (FILE *) object, as is the case after a successful call to the flockfile() or ftrylockfile() functions. If threads are disabled, then fgetwc_unlocked is equivalent to fgetwc.

The getwc and getwc_unlocked functions or macros functions identically to fgetwc and fgetwc_unlocked. It may be implemented as a macro, and may evaluate its argument more than once. There is no reason ever to use it.

_fgetwc_r, _getwc_r, _fgetwc_unlocked_r, and _getwc_unlocked_r are simply reentrant versions of the above functions that are passed the additional reentrant structure pointer argument: ptr.

Returns
The next wide character cast to wint_t, unless there is no more data, or the host system reports a read error; in either of these situations, fgetwc and getwc return WEOF.

You can distinguish the two situations that cause an EOF result by using the ferror and feof functions.

4.13 fgetwc, getwc, fgetwc_unlocked, getwc_unlocked—get a wide character from a file or stream

4.13 `fgetwc`, `getwc`, `fgetwc_unlocked`, `getwc_unlocked`—get a wide character from a file or stream