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.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)