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

       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

       fwrite - binary output

       #include <stdio.h>

       size_t fwrite(const void *restrict ptr, size_t size, size_t nitems,
              FILE *restrict stream);

       The fwrite() function shall write, from the array pointed to by ptr, up to nitems elements whose size is speci-
       fied 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 indicator 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().

       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 indicate the error.

       Refer to fputc().

       The following sections are informative.


       Because of possible differences in element length and byte ordering, files written using fwrite() are  applica-
       tion-dependent, and possibly cannot be read using fread() by a different application or by the same application
       on a different processor.



       ferror(), fopen(), printf(), putc(), puts(), write(), the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  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 Stan-
       dard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The original Standard can be
       obtained online at .

IEEE/The Open Group                  2003                           FWRITE(3P)