PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       fgetc — get a byte from a stream

SYNOPSIS

       #include <stdio.h>

       int fgetc(FILE *stream);

DESCRIPTION

       The  functionality  described  on  this  reference  page is aligned with the ISO C standard. Any conflict
       between the requirements described  here  and  the  ISO C  standard  is  unintentional.  This  volume  of
       POSIX.1‐2017 defers to the ISO C standard.

       If  the  end-of-file  indicator  for  the input stream pointed to by stream is not set and a next byte is
       present, the fgetc() function shall obtain the next byte as an unsigned char converted to  an  int,  from
       the  input stream pointed to by stream, and advance the associated file position indicator for the stream
       (if defined). Since fgetc() operates on bytes, reading a character consisting of multiple bytes  (or  ``a
       multi-byte character'') may require multiple calls to fgetc().

       The  fgetc()  function  may  mark  the  last data access timestamp of the file associated with stream for
       update. The last data access timestamp shall be marked for update by the first  successful  execution  of
       fgetc(),  fgets(),  fread(), fscanf(), getc(), getchar(), getdelim(), getline(), gets(), or scanf() using
       stream that returns data not supplied by a prior call to ungetc().

RETURN VALUE

       Upon successful completion, fgetc() shall return the next byte  from  the  input  stream  pointed  to  by
       stream.  If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
       of-file  indicator  for the stream shall be set and fgetc() shall return EOF. If a read error occurs, the
       error indicator for the stream shall be set, fgetc() shall return EOF, and shall set  errno  to  indicate
       the error.

ERRORS

       The fgetc() function shall fail if data needs to be read and:

       EAGAIN The  O_NONBLOCK  flag  is  set  for  the file descriptor underlying stream and the thread would be
              delayed in the fgetc() operation.

       EBADF  The file descriptor underlying stream is not a valid file descriptor open for reading.

       EINTR  The read operation was terminated due to the receipt of a signal, and no data was transferred.

       EIO    A physical I/O error has occurred, or the process is in a background process group  attempting  to
              read  from  its  controlling  terminal,  and  either the calling thread is blocking SIGTTIN or the
              process is ignoring SIGTTIN or the process group of the process is orphaned.  This error may  also
              be generated for implementation-defined reasons.

       EOVERFLOW
              The  file  is  a  regular  file  and  an  attempt was made to read at or beyond the offset maximum
              associated with the corresponding stream.

       The fgetc() function may fail if:

       ENOMEM Insufficient storage space is available.

       ENXIO  A request was made of a nonexistent device, or the request was outside  the  capabilities  of  the
              device.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       If the integer value returned by fgetc() is stored into a variable of type char and then compared against
       the  integer constant EOF, the comparison may never succeed, because sign-extension of a variable of type
       char on widening to integer is implementation-defined.

       The ferror() or feof() functions must be used to distinguish between an error condition  and  an  end-of-
       file condition.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section  2.5,  Standard  I/O  Streams,  feof(),  ferror(), fgets(), fread(), fscanf(), getchar(), getc(),
       gets(), ungetc()

       The Base Definitions volume of POSIX.1‐2017, <stdio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                         FGETC(3POSIX)