1.\" $NetBSD: fread.3,v 1.5 1995/02/02 01:15:42 jtc Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Chris Torek and the American National Standards Committee X3, 8.\" on Information Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" @(#)fread.3 8.2 (Berkeley) 3/8/94 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 SYNOPSIS 48.Fd #include <stdio.h> 49.Ft size_t 50.Fn fread "void *ptr" "size_t size" "size_t nmemb" "FILE *stream" 51.Ft size_t 52.Fn fwrite "const void *ptr" "size_t size" "size_t nmemb" "FILE *stream" 53.Sh DESCRIPTION 54The function 55.Fn fread 56reads 57.Fa nmemb 58objects, each 59.Fa size 60bytes long, from the stream pointed to by 61.Fa stream , 62storing them at the location given by 63.Fa ptr . 64.Pp 65The function 66.Fn fwrite 67writes 68.Fa nmemb 69objects, each 70.Fa size 71bytes long, to the stream pointed to by 72.Fa stream , 73obtaining them from the location given by 74.Fa ptr . 75.Sh RETURN VALUES 76The functions 77.Fn fread 78and 79.Fn fwrite 80advance the file position indicator for the stream 81by the number of bytes read or written. 82They return the number of objects read or written. 83If an error occurs, or the end-of-file is reached, 84the return value is a short object count (or zero). 85.Pp 86The function 87.Fn fread 88does not distinguish between end-of-file and error, and callers 89must use 90.Xr feof 3 91and 92.Xr ferror 3 93to determine which occurred. 94The function 95.Fn fwrite 96returns a value less than 97.Fa nmemb 98only if a write error has occurred. 99.Sh SEE ALSO 100.Xr read 2 , 101.Xr write 2 102.Sh STANDARDS 103The functions 104.Fn fread 105and 106.Fn fwrite 107conform to 108.St -ansiC . 109