4.10 fgetc, fgetc_unlocked—get a character from a file or stream

Synopsis

#include <stdio.h>
int fgetc(FILE *fp);

#define _BSD_SOURCE
#include <stdio.h>
int fgetc_unlocked(FILE *fp);

#include <stdio.h>
int _fgetc_r(struct _reent *ptr, FILE *fp);

#define _BSD_SOURCE
#include <stdio.h>
int _fgetc_unlocked_r(struct _reent *ptr, FILE *fp);

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

For a macro version of this function, see getc.

fgetc_unlocked is a non-thread-safe version of fgetc. fgetc_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 fgetc_unlocked is equivalent to fgetc.

The functions _fgetc_r and _fgetc_unlocked_r are simply reentrant versions that are passed the additional reentrant structure pointer argument: ptr.

Returns
The next character (read as an unsigned char, and cast to int), unless there is no more data, or the host system reports a read error; in either of these situations, fgetc returns EOF.

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

Portability
ANSI C requires fgetc.

fgetc_unlocked is a BSD extension also provided by GNU libc.

Supporting OS subroutines required: close, fstat, isatty, lseek, read, sbrk, write.