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FWRITE(3P)                 POSIX Programmer's Manual                FWRITE(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       fwrite - binary output
SYNOPSIS
       #include <stdio.h>
       size_t fwrite(const void *restrict ptr, size_t size, size_t nitems,
              FILE *restrict stream);

DESCRIPTION
       The fwrite() function shall write, from the array pointed to by ptr, up
       to  nitems  elements  whose  size  is  specified by size, to the stream
       pointed to by stream.  For each object, size calls shall be made to the
       fputc()  function,  taking  the  values  (in  order)  from  an array of
       unsigned char exactly overlaying the object. The file-position  indica-
       tor  for  the  stream  (if  defined) shall be advanced by the number of
       bytes successfully written. If an error occurs, the resulting value  of
       the file-position indicator for the stream is unspecified.
       The st_ctime and st_mtime fields of the file shall be marked for update
       between the successful execution of fwrite() and  the  next  successful
       completion  of  a call to fflush() or fclose() on the same stream, or a
       call to exit() or abort().
RETURN VALUE
       The fwrite() function shall return the number of elements  successfully
       written, which may be less than nitems if a write error is encountered.
       If size or nitems is 0, fwrite() shall return 0 and the  state  of  the
       stream remains unchanged. Otherwise, if a write error occurs, the error
       indicator for the stream shall be set,  and errno shall be set to indi-
       cate the error.
ERRORS
       Refer to fputc().
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       Because  of  possible  differences in element length and byte ordering,
       files written using fwrite() are  application-dependent,  and  possibly
       cannot  be read using fread() by a different application or by the same
       application on a different processor.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       ferror(), fopen(), printf(), putc(), puts(), write(), the Base  Defini-
       tions volume of IEEE Std 1003.1-2001, <stdio.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                           FWRITE(3P)