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 GroupA newer edition of this document exists here
NAME
putc - put a byte on a stream
SYNOPSIS
#include <stdio.h>
int putc(int c, FILE *stream);
DESCRIPTION
[CX] ![[Option Start]](../images/opt-start.gif)
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]](../images/opt-end.gif)
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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