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FGETC(3P)                  POSIX Programmer's Manual                 FGETC(3P)
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.1-2008
       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 sup-
       plied 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 sig-
              nal, and no data was transferred.
       EIO    A physical I/O error has occurred, or the process is in a  back-
              ground  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 com-
       parison 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.1-2008, <stdio.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  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.unix.org/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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                            FGETC(3P)