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