fread(3) — Linux manual page


FREAD(3)                  Linux Programmer's Manual                 FREAD(3)

NAME         top

       fread, fwrite - binary stream input/output

SYNOPSIS         top

       #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         top

       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         top

       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         top

       For an explanation of the terms used in this section, see

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

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, C89.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.07 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

GNU                              2015-07-23                         FREAD(3)

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