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 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().

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
       indicate 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 Definitions 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 .