getc(3p) — Linux manual page

GETC(3P)                POSIX Programmer's Manual               GETC(3P)

PROLOG         top

       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         top

       getc — get a byte from a stream

SYNOPSIS         top

       #include <stdio.h>

       int getc(FILE *stream);

DESCRIPTION         top

       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.

       The getc() function shall be equivalent to fgetc(3p), 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         top

       Refer to fgetc(3p).

ERRORS         top

       Refer to fgetc(3p).

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       If the integer value returned by getc() 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.

       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         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Section 2.5, Standard I/O Streams, fgetc(3p)

       The Base Definitions volume of POSIX.1‐2017, stdio.h(0p)

COPYRIGHT         top

       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                          GETC(3P)

Pages that refer to this page: stdio.h(0p),  fgetc(3p),  fgets(3p),  fread(3p),  fscanf(3p),  getchar(3p),  getc_unlocked(3p),  stdin(3p),  ungetc(3p)

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