1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)putc.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/stdio/putc.3,v 1.16 2007/01/09 00:28:07 imp Exp $ 34.\" 35.Dd November 22, 2020 36.Dt PUTC 3 37.Os 38.Sh NAME 39.Nm fputc , 40.Nm fputc_unlocked , 41.Nm putc , 42.Nm putc_unlocked , 43.Nm putchar , 44.Nm putchar_unlocked , 45.Nm putw 46.Nd output a character or word to a stream 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.In stdio.h 51.Ft int 52.Fn fputc "int c" "FILE *stream" 53.Ft int 54.Fn fputc_unlocked "int c" "FILE *stream" 55.Ft int 56.Fn putc "int c" "FILE *stream" 57.Ft int 58.Fn putc_unlocked "int c" "FILE *stream" 59.Ft int 60.Fn putchar "int c" 61.Ft int 62.Fn putchar_unlocked "int c" 63.Ft int 64.Fn putw "int w" "FILE *stream" 65.Sh DESCRIPTION 66The 67.Fn fputc 68function 69writes the character 70.Fa c 71(converted to an ``unsigned char'') 72to the output stream pointed to by 73.Fa stream . 74.Pp 75The 76.Fn putc 77macro acts essentially identically to 78.Fn fputc , 79but is a macro that expands in-line. 80It may evaluate 81.Fa stream 82more than once, so arguments given to 83.Fn putc 84should not be expressions with potential side effects. 85.Pp 86The 87.Fn putchar 88function 89is identical to 90.Fn putc 91with an output stream of 92.Dv stdout . 93.Pp 94The 95.Fn putw 96function 97writes the specified 98.Vt int 99to the named output 100.Fa stream . 101.Pp 102The 103.Fn fputc_unlocked , 104.Fn putc_unlocked , 105and 106.Fn putchar_unlocked 107functions are equivalent to 108.Fn fputc , 109.Fn putc , 110and 111.Fn putchar 112respectively, 113except that the caller is responsible for locking the stream 114with 115.Xr flockfile 3 116before calling them. 117These functions may be used to avoid the overhead of locking the stream 118for each character, and to avoid output being interspersed from multiple 119threads writing to the same stream. 120.Sh RETURN VALUES 121The functions, 122.Fn fputc , 123.Fn putc , 124.Fn putchar , 125.Fn putc_unlocked 126and 127.Fn putchar_unlocked 128return the character written. 129If an error occurs, the value 130.Dv EOF 131is returned. 132The 133.Fn putw 134function 135returns 0 on success; 136.Dv EOF 137is returned if 138a write error occurs, 139or if an attempt is made to write a read-only stream. 140.Sh SEE ALSO 141.Xr ferror 3 , 142.Xr flockfile 3 , 143.Xr fopen 3 , 144.Xr getc 3 , 145.Xr putwc 3 , 146.Xr stdio 3 147.Sh STANDARDS 148The functions 149.Fn fputc , 150.Fn putc , 151and 152.Fn putchar , 153conform to 154.St -isoC . 155The 156.Fn putc_unlocked 157and 158.Fn putchar_unlocked 159functions conform to 160.St -p1003.1-2001 . 161A function 162.Fn putw 163function appeared in 164.At v6 . 165.Sh BUGS 166The size and byte order of an 167.Vt int 168varies from one machine to another, and 169.Fn putw 170is not recommended for portable applications. 171