fread.3s

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)fread.3s	8.1	9/11/90
.TH fread 3s
.SH Name
fread, fwrite \- buffered binary input/output
.SH Syntax
.B #include <stdio.h>
.nf

.B size_t fread\^(\fIptr, size, nitems, stream\fP)
.B void *\fIptr\fP;
.B size_t \fIsize\fP, \fInitems\fP;
.B FILE *\fIstream\fP;

.B size_t fwrite\^(\fIptr, size, nitems, stream\fP)
.B void *\fIptr\fP; 
.B size_t \fIsize, nitems\fP; 
.B FILE *\fIstream\fP;
.fi
.SH Description
.NXR "fread subroutine"
.NXR "fwrite subroutine"
.NXR "stream" "reading"
.NXR "stream" "appending"
The
.PN fread
function reads into a block beginning at
.IR ptr ,
.I nitems
of data of the size \fIsize\fP (usually sizeof 
.IR *ptr )
from the named input
.IR stream .
It returns the number of items actually read.
.PP
If
.I stream
is
.B stdin
and the standard output is line buffered, then any partial output line
will be flushed before any call to
.MS read 2
to satisfy the
.PN fread .
.PP
The
.PN fwrite
function appends, at most,
.I nitems
of data of the size \fIsize\fP (usually sizeof
.IR *ptr )
beginning at
.I ptr
to the named output
.IR stream .
It returns the number of items actually written.
.SH Return Values
The
.PN fread
and
.PN fwrite
functions return
0
upon end of file or error.
.SH See Also
read(2), write(2), fopen(3s), getc(3s), gets(3s),
printf(3s), putc(3s), puts(3s), scanf(3s)