xref: /freebsd/lib/libc/stdio/putc.3 (revision 6b3455a7665208c366849f0b2b3bc916fb97516e)
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. All advertising materials mentioning features or use of this software
17.\"    must display the following acknowledgement:
18.\"	This product includes software developed by the University of
19.\"	California, Berkeley and its contributors.
20.\" 4. Neither the name of the University nor the names of its contributors
21.\"    may be used to endorse or promote products derived from this software
22.\"    without specific prior written permission.
23.\"
24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34.\" SUCH DAMAGE.
35.\"
36.\"     @(#)putc.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD$
38.\"
39.Dd January 10, 2003
40.Dt PUTC 3
41.Os
42.Sh NAME
43.Nm fputc ,
44.Nm putc ,
45.Nm putc_unlocked ,
46.Nm putchar ,
47.Nm putchar_unlocked ,
48.Nm putw
49.Nd output a character or word to a stream
50.Sh LIBRARY
51.Lb libc
52.Sh SYNOPSIS
53.In stdio.h
54.Ft int
55.Fn fputc "int c" "FILE *stream"
56.Ft int
57.Fn putc "int c" "FILE *stream"
58.Ft int
59.Fn putc_unlocked "int c" "FILE *stream"
60.Ft int
61.Fn putchar "int c"
62.Ft int
63.Fn putchar_unlocked "int c"
64.Ft int
65.Fn putw "int w" "FILE *stream"
66.Sh DESCRIPTION
67The
68.Fn fputc
69function
70writes the character
71.Fa c
72(converted to an ``unsigned char'')
73to the output stream pointed to by
74.Fa stream .
75.Pp
76The
77.Fn putc
78macro acts essentially identically to
79.Fn fputc ,
80but is a macro that expands in-line.
81It may evaluate
82.Fa stream
83more than once, so arguments given to
84.Fn putc
85should not be expressions with potential side effects.
86.Pp
87The
88.Fn putchar
89function
90is identical to
91.Fn putc
92with an output stream of
93.Dv stdout .
94.Pp
95The
96.Fn putw
97function
98writes the specified
99.Vt int
100to the named output
101.Fa stream .
102.Pp
103The
104.Fn putc_unlocked
105and
106.Fn putchar_unlocked
107functions are equivalent to
108.Fn putc
109and
110.Fn putchar
111respectively,
112except that the caller is responsible for locking the stream
113with
114.Xr flockfile 3
115before calling them.
116These functions may be used to avoid the overhead of locking the stream
117for each character, and to avoid output being interspersed from multiple
118threads writing to the same stream.
119.Sh RETURN VALUES
120The functions,
121.Fn fputc ,
122.Fn putc ,
123.Fn putchar ,
124.Fn putc_unlocked
125and
126.Fn putchar_unlocked
127return the character written.
128If an error occurs, the value
129.Dv EOF
130is returned.
131The
132.Fn putw
133function
134returns 0 on success;
135.Dv EOF
136is returned if
137a write error occurs,
138or if an attempt is made to write a read-only stream.
139.Sh SEE ALSO
140.Xr ferror 3 ,
141.Xr flockfile 3 ,
142.Xr fopen 3 ,
143.Xr getc 3 ,
144.Xr putwc 3 ,
145.Xr stdio 3
146.Sh STANDARDS
147The functions
148.Fn fputc ,
149.Fn putc ,
150and
151.Fn putchar ,
152conform to
153.St -isoC .
154The
155.Fn putc_unlocked
156and
157.Fn putchar_unlocked
158functions conform to
159.St -p1003.1-2001 .
160A function
161.Fn putw
162function appeared in
163.At v6 .
164.Sh BUGS
165The size and byte order of an
166.Vt int
167varies from one machine to another, and
168.Fn putw
169is not recommended for portable applications.
170