Name

fread, fwrite — binary stream input/output

Synopsis

#include <stdio.h>
size_t fread( void *ptr,
  size_t size,
  size_t nmemb,
  FILE *stream);
 
size_t fwrite( const void *ptr,
  size_t size,
  size_t nmemb,
  FILE *stream);
 

DESCRIPTION

The function fread() reads nmemb elements of data, each size bytes long, from the stream pointed to by stream, storing them at the location given by ptr.

The function fwrite() writes nmemb elements of data, each size bytes long, to the stream pointed to by stream, obtaining them from the location given by ptr.

For nonlocking counterparts, see unlocked_stdio(3).

RETURN VALUE

On success, fread() and fwrite() return the number of items read or written. This number equals the number of bytes transferred only when size is 1. If an error occurs, or the end of the file is reached, the return value is a short item count (or zero).

fread() does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred.

CONFORMING TO

C89, POSIX.1-2001.

SEE ALSO

read(2), write(2), feof(3), ferror(3), unlocked_stdio(3)

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright (c) 1990, 1991 The Regents of the University of California.
All rights reserved.

This code is derived from software contributed to Berkeley by
Chris Torek and the American National Standards Committee X3,
on Information Processing Systems.

%%%LICENSE_START(BSD_4_CLAUSE_UCB)
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modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
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This product includes software developed by the University of
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4. Neither the name of the University nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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    (#)fread.3 6.6 (Berkeley) 6/29/91

Converted for Linux, Mon Nov 29 15:37:33 1993, faithcs.unc.edu
Sun Feb 19 21:26:54 1995 by faith, return values
Modified Thu Apr 20 20:43:53 1995 by Jim Van Zandt <jrvvanzandt.mv.com>
Modified Fri May 17 10:21:51 1996 by Martin Schulze <joeyinfodrom.north.de>