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 .