The Open Group Base Specifications Issue 7, 2018 edition
IEEE Std 1003.1-2017 (Revision of IEEE Std 1003.1-2008)
Copyright © 2001-2018 IEEE and The Open Group

NAME

putc - put a byte on a stream

SYNOPSIS

#include <stdio.h>

int putc(int
c, 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 POSIX.1-2017 defers to the ISO C standard. [Option End]

The putc() function shall be equivalent to fputc(), 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 fputc.

ERRORS

Refer to fputc.


The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

Since it may be implemented as a macro, putc() may treat a stream argument with side-effects incorrectly. In particular, putc(c,*f++) does not necessarily work correctly. Therefore, use of this function is not recommended in such situations; fputc() should be used instead.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

Standard I/O Streams, fputc

XBD <stdio.h>

CHANGE HISTORY

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

Issue 7

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0470 [14] is applied.

End of informative text.

 

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