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