xref: /illumos-gate/usr/src/man/man3c/fputc.3c (revision bbf21555)

Sun Microsystems, Inc. gratefully acknowledges The Open Group for
permission to reproduce portions of its copyrighted documentation.
Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.

The Institute of Electrical and Electronics Engineers and The Open
Group, have given us permission to reprint portions of their
documentation.

In the following statement, the phrase ``this text'' refers to portions
of the system documentation.

Portions of this text are reprinted and reproduced in electronic form
in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6,
Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy
between these versions 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
http://www.opengroup.org/unix/online.html.

This notice shall appear on any product containing this material.

The contents of this file are subject to the terms of the
Common Development and Distribution License (the "License").
You may not use this file except in compliance with the License.

You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
or http://www.opensolaris.org/os/licensing.
See the License for the specific language governing permissions
and limitations under the License.

When distributing Covered Code, include this CDDL HEADER in each
file and include the License file at usr/src/OPENSOLARIS.LICENSE.
If applicable, add the following below this CDDL HEADER, with the
fields enclosed by brackets "[]" replaced with your own identifying
information: Portions Copyright [yyyy] [name of copyright owner]


Portions Copyright (c) 1992, X/Open Company Limited. All Rights Reserved.
Copyright (c) 2003, Sun Microsystems, Inc. All Rights Reserved.

FPUTC 3C "March 25, 2020"
NAME
fputc, putc, putc_unlocked, putchar, putchar_unlocked, putw - put a byte on a stream
SYNOPSIS
#include <stdio.h>

int fputc(int c, FILE *stream);

int putc(int c, FILE *stream);

int putc_unlocked(int c, FILE *stream);

int putchar(int c);

int putchar_unlocked(int c);

int putw(int w, FILE *stream);
DESCRIPTION
The fputc() function writes the byte specified by c (converted to an unsigned char) to the output stream pointed to by stream, at the position indicated by the associated file-position indicator for the stream (if defined), and advances the indicator appropriately. If the file cannot support positioning requests, or if the stream was opened with append mode, the byte is appended to the output stream.

The st_ctime and st_mtime fields of the file will be marked for update between the successful execution of fputc() and the next successful completion of a call to fflush(3C) or fclose(3C) on the same stream or a call to exit(3C) or abort(3C).

The putc() routine behaves like fputc(), except that it is implemented as a macro. It runs faster than fputc(), but it takes up more space per invocation and its name cannot be passed as an argument to a function call.

The call putchar(c) is equivalent to putc(c, stdout). The putchar() routine is implemented as a macro.

The putc_unlocked() and putchar_unlocked() routines are variants of putc() and putchar(), respectively, that do not lock the stream. It is the caller's responsibility to acquire the stream lock before calling these routines and releasing the lock afterwards; see flockfile(3C) and stdio(3C). These routines are implemented as macros.

The putw() function writes the word (that is, type int) w to the output stream (at the position at which the file offset, if defined, is pointing). The size of a word is the size of a type int and varies from machine to machine. The putw() function neither assumes nor causes special alignment in the file.

The st_ctime and st_mtime fields of the file will be marked for update between the successful execution of putw() and the next successful completion of a call to fflush(3C) or fclose(3C) on the same stream or a call to exit(3C) or abort(3C).

RETURN VALUES
Upon successful completion, fputc(), putc(), putc_unlocked(), putchar(), and putchar_unlocked() return the value that was written. Otherwise, these functions return EOF, the error indicator for the stream is set, and errno is set to indicate the error.

Upon successful completion, putw() returns 0. Otherwise, it returns a non-zero value, sets the error indicator for the associated stream, and sets errno to indicate the error.

An unsuccessful completion will occur, for example, if the file associated with stream is not open for writing or if the output file cannot grow.

ERRORS
The fputc(), putc(), putc_unlocked(), putchar(), putchar_unlocked(), and putw() functions will fail if either the stream is unbuffered or the stream's buffer needs to be flushed, and: EAGAIN

The O_NONBLOCK flag is set for the file descriptor underlying stream and the process would be delayed in the write operation.

EBADF

The file descriptor underlying stream is not a valid file descriptor open for writing.

EFBIG

An attempt was made to write to a file that exceeds the maximum file size or the process' file size limit.

EFBIG

The file is a regular file and an attempt was made to write at or beyond the offset maximum.

EINTR

The write operation was terminated due to the receipt of a signal, and no data was transferred.

EIO

A physical I/O error has occurred, or the process is a member of a background process group attempting to write to its controlling terminal, TOSTOP is set, the process is neither ignoring nor blocking SIGTTOU and the process group of the process is orphaned. stream was created by open_wmemstream(3C) and a wide-character or byte sequence buffered is invalid in the current locale. This error may also be returned under implementation-dependent conditions.

ENOSPC

There was no free space remaining on the device containing the file.

EPIPE

An attempt is made to write to a pipe or FIFO that is not open for reading by any process. A SIGPIPE signal will also be sent to the calling thread.

The fputc(), putc(), putc_unlocked(), putchar(), putchar_unlocked(), and putw() functions may fail if: ENOMEM

Insufficient storage space is available.

ENXIO

A request was made of a non-existent device, or the request was outside the capabilities of the device.

USAGE
Functions exist for the putc(), putc_unlocked(), putchar(), and putchar_unlocked() macros. To get the function form, the macro name must be undefined (for example, #undef putc).

When the macro forms are used, putc() and putc_unlocked() evaluate the stream argument more than once. In particular, putc(c, *f++); does not work sensibly. The fputc() function should be used instead when evaluating the stream argument has side effects.

Because of possible differences in word length and byte ordering, files written using putw() are implementation-dependent, and possibly cannot be read using getw(3C) by a different application or by the same application running in a different environment.

The putw() function is inherently byte stream oriented and is not tenable in the context of either multibyte character streams or wide-character streams. Application programmers are encouraged to use one of the character-based output functions instead.

ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability
fputc(), putc(), putc_unlocked(), putchar(), and putchar_unlocked() are Standard.
MT-Level See NOTES below.
SEE ALSO
getrlimit(2), ulimit(2) write(2), Intro (3), abort (3C), exit (3C), fclose (3C), ferror (3C), fflush (3C), flockfile (3C), printf (3C), putc (3C), puts (3C), setbuf (3C), stdio (3C), attributes (7), standards (7)
NOTES
The fputc(), putc(), putchar(), and putw() routines are MT-Safe in multithreaded applications. The putc_unlocked() and putchar_unlocked() routines are unsafe in multithreaded applications.