GETC(3P) POSIX Programmer's Manual GETC(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.
NAMEgetc — get a byte from a stream
SYNOPSIS
#include <stdio.h>
int getc(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.
The getc() function shall be equivalent to fgetc(), except that if it
is implemented as a macro it may evaluate stream more than once, so the
argument should never be an expression with side-effects.
RETURN VALUE
Refer to fgetc().
ERRORS
Refer to fgetc().
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
If the integer value returned by getc() 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.
Since it may be implemented as a macro, getc() may treat incorrectly a
stream argument with side-effects. In particular, getc(*f++) does not
necessarily work as expected. Therefore, use of this function should be
preceded by "#undefgetc" in such situations; fgetc() could also be
used.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
Section 2.5, Standard I/O Streams, fgetc()
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 GETC(3P)
