The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

NAME

getc - get a byte from a stream

SYNOPSIS

#include <stdio.h>

int getc(FILE *
stream);

DESCRIPTION

[CX] [Option Start] 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 IEEE Std 1003.1-2001 defers to the ISO C standard. [Option End]

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 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 "#undef getc" in such situations; fgetc() could also be used.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

fgetc(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

End of informative text.

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