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.\" @(#)fread.3 8.2 (Berkeley) 3/8/94 37.\" $FreeBSD: src/lib/libc/stdio/fread.3,v 1.5.2.3 2001/12/14 18:33:57 ru Exp $ 38.\" $DragonFly: src/lib/libc/stdio/fread.3,v 1.2 2003/06/17 04:26:46 dillon Exp $ 39.\" 40.Dd March 8, 1994 41.Dt FREAD 3 42.Os 43.Sh NAME 44.Nm fread , 45.Nm fwrite 46.Nd binary stream input/output 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.In stdio.h 51.Ft size_t 52.Fn fread "void *ptr" "size_t size" "size_t nmemb" "FILE *stream" 53.Ft size_t 54.Fn fwrite "const void *ptr" "size_t size" "size_t nmemb" "FILE *stream" 55.Sh DESCRIPTION 56The function 57.Fn fread 58reads 59.Fa nmemb 60objects, each 61.Fa size 62bytes long, from the stream pointed to by 63.Fa stream , 64storing them at the location given by 65.Fa ptr . 66.Pp 67The function 68.Fn fwrite 69writes 70.Fa nmemb 71objects, each 72.Fa size 73bytes long, to the stream pointed to by 74.Fa stream , 75obtaining them from the location given by 76.Fa ptr . 77.Sh RETURN VALUES 78The functions 79.Fn fread 80and 81.Fn fwrite 82advance the file position indicator for the stream 83by the number of bytes read or written. 84They return the number of objects read or written. 85If an error occurs, or the end-of-file is reached, 86the return value is a short object count (or zero). 87.Pp 88The function 89.Fn fread 90does not distinguish between end-of-file and error, and callers 91must use 92.Xr feof 3 93and 94.Xr ferror 3 95to determine which occurred. 96The function 97.Fn fwrite 98returns a value less than 99.Fa nmemb 100only if a write error has occurred. 101.Sh SEE ALSO 102.Xr read 2 , 103.Xr write 2 104.Sh STANDARDS 105The functions 106.Fn fread 107and 108.Fn fwrite 109conform to 110.St -isoC . 111