getc man page

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.

getc — 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.

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 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.

See Also

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

The Base Definitions volume of POSIX.1‐2008, <stdio.h>

Info

2013 IEEE/The Open Group POSIX Programmer's Manual