1GETC(3P)                   POSIX Programmer's Manual                  GETC(3P)
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PROLOG

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

12       getc — get a byte from a stream
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SYNOPSIS

15       #include <stdio.h>
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17       int getc(FILE *stream);
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DESCRIPTION

20       The functionality described on this reference page is aligned with  the
21       ISO C  standard.  Any  conflict between the requirements described here
22       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
23       defers to the ISO C standard.
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25       The  getc()  function shall be equivalent to fgetc(), except that if it
26       is implemented as a macro it may evaluate stream more than once, so the
27       argument should never be an expression with side-effects.
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RETURN VALUE

30       Refer to fgetc().
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ERRORS

33       Refer to fgetc().
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35       The following sections are informative.
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EXAMPLES

38       None.
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APPLICATION USAGE

41       If  the  integer  value returned by getc() is stored into a variable of
42       type char and then compared against the integer constant EOF, the  com‐
43       parison may never succeed, because sign-extension of a variable of type
44       char on widening to integer is implementation-defined.
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46       Since it may be implemented as a macro, getc() may treat incorrectly  a
47       stream  argument  with side-effects. In particular, getc(*f++) does not
48       necessarily work as expected. Therefore, use of this function should be
49       preceded  by  "#undefgetc"  in  such  situations; fgetc() could also be
50       used.
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RATIONALE

53       None.
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FUTURE DIRECTIONS

56       None.
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SEE ALSO

59       Section 2.5, Standard I/O Streams, fgetc()
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61       The Base Definitions volume of POSIX.1‐2017, <stdio.h>
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64       Portions of this text are reprinted and reproduced in  electronic  form
65       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
66       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
67       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
68       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
69       event of any discrepancy between this version and the original IEEE and
70       The Open Group Standard, the original IEEE and The Open Group  Standard
71       is  the  referee document. The original Standard can be obtained online
72       at http://www.opengroup.org/unix/online.html .
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74       Any typographical or formatting errors that appear  in  this  page  are
75       most likely to have been introduced during the conversion of the source
76       files to man page format. To report such errors,  see  https://www.ker‐
77       nel.org/doc/man-pages/reporting_bugs.html .
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81IEEE/The Open Group                  2017                             GETC(3P)
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