Section: POSIX Programmer's Manual (3P)
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.
--- get a byte from a stream
int getc(FILE *stream);
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.
function shall be equivalent to
except that if it is implemented as a macro it may evaluate
more than once, so the argument should never be an expression with
The following sections are informative.
If the integer value returned by
is stored into a variable of type
and then compared against the integer constant EOF, the comparison may
never succeed, because sign-extension of a variable of type
on widening to integer is implementation-defined.
Since it may be implemented as a macro,
may treat incorrectly a
argument with side-effects. In particular,
does not necessarily work as expected. Therefore, use of this function
should be preceded by
in such situations;
could also be used.
, Standard I/O Streams,
The Base Definitions volume of POSIX.1-2008,
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
Electrical 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
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