FREAD

Section: Linux Programmer's Manual (3)
Updated: 2015-07-23
Index Return to Main Contents

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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 items 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 items 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.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
fread(), fwrite()	Thread safety	MT-Safe

 

CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C89.  

SEE ALSO

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

COLOPHON

This page is part of release 4.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

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Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ATTRIBUTES

CONFORMING TO

SEE ALSO

COLOPHON