1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
.\"
.\" 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]
.\"
.\"
.\" Copyright 1989 AT&T
.\" Copyright (c) 1997, The Open Group. All Rights Reserved.
.\" Portions Copyright (c) 2002, Sun Microsystems, Inc. All Rights Reserved
.\"
.TH FREAD 3C "Jul 24, 2002"
.SH NAME
fread \- binary input
.SH SYNOPSIS
.LP
.nf
#include <stdio.h>
\fBsize_t\fR \fBfread\fR(\fBvoid *\fR\fIptr\fR, \fBsize_t\fR \fIsize\fR, \fBsize_t\fR \fInitems\fR, \fBFILE *\fR\fIstream\fR);
.fi
.SH DESCRIPTION
.sp
.LP
The \fBfread()\fR function reads into the array pointed to by \fIptr\fR up to
\fInitems\fR elements whose size is specified by \fIsize\fR in bytes, from the
stream pointed to by \fIstream\fR. For each object, \fIsize\fR calls are made
to the \fBfgetc\fR(3C) function and the results stored, in the order read, in
an array of \fBunsigned char\fR exactly overlaying the object. The
file-position indicator for the stream (if defined) is advanced by the number
of bytes successfully read. If an error occurs, the resulting value of the
file-position indicator for the stream is unspecified. If a partial element is
read, its value is unspecified.
.sp
.LP
The \fBfread()\fR function may mark the \fBst_atime\fR field of the file
associated with \fIstream\fR for update. The \fBst_atime\fR field will be
marked for update by the first successful execution of \fBfgetc\fR(3C),
\fBfgets\fR(3C), \fBfgetwc\fR(3C), \fBfgetws\fR(3C), \fBfread()\fR,
\fBfscanf\fR(3C), \fBgetc\fR(3C), \fBgetchar\fR(3C), \fBgets\fR(3C), or
\fBscanf\fR(3C) using \fIstream\fR that returns data not supplied by a prior
call to \fBungetc\fR(3C) or \fBungetwc\fR(3C).
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBfread()\fR returns the number of elements
successfully read, which is less than \fInitems\fR only if a read error or
end-of-file is encountered. If \fIsize\fR or \fInitems\fR is 0, \fBfread()\fR
returns 0 and the contents of the array and the state of the stream remain
unchanged. Otherwise, if a read error occurs, the error indicator for the
stream is set and \fBerrno\fR is set to indicate the error.
.SH ERRORS
.sp
.LP
Refer to \fBfgetc\fR(3C).
.SH EXAMPLES
.LP
\fBExample 1 \fRReading from a Stream
.sp
.LP
The following example reads a single element from the \fIfp\fR stream into the
array pointed to by \fIbuf\fR.
.sp
.in +2
.nf
#include <stdio.h>
\&...
size_t bytes_read;
char buf[100];
FILE *fp;
\&...
bytes_read = fread(buf, sizeof(buf), 1, fp);
\&...
.fi
.in -2
.SH USAGE
.sp
.LP
The \fBferror()\fR or \fBfeof()\fR functions must be used to distinguish
between an error condition and end-of-file condition. See \fBferror\fR(3C).
.sp
.LP
Because of possible differences in element length and byte ordering, files
written using \fBfwrite\fR(3C) are application-dependent, and possibly cannot
be read using \fBfread()\fR by a different application or by the same
application on a different processor.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp
.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE ATTRIBUTE VALUE
_
Interface Stability Standard
_
MT-Level MT-Safe
.TE
.SH SEE ALSO
.sp
.LP
\fBread\fR(2), \fBfclose\fR(3C), \fBferror\fR(3C), \fBfopen\fR(3C),
\fBgetc\fR(3C), \fBgets\fR(3C), \fBprintf\fR(3C), \fBputc\fR(3C),
\fBputs\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)
|
