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

Synopsis

     #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.

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

fgetwc_unlocked and getwc_unlocked are GNU extensions.