NAME

       fread - binary input

SYNOPSIS

       #include <stdio.h>

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

DESCRIPTION

       The  fread()  function  shall  read  into the array pointed to by ptr up to nitems elements whose size is
       specified by size in bytes, from the stream pointed to by stream.  For each object, size calls  shall  be
       made  to  the  fgetc()  function  and the results stored, in the order read, in 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 read. If an error occurs, the resulting value of the file position
       indicator for the stream is unspecified. If a partial element is read, its value is unspecified.

       The fread() function may mark the st_atime field of the file  associated  with  stream  for  update.  The
       st_atime  field  shall  be  marked  for  update  by  the  first successful execution of fgetc(), fgets(),
       fgetwc(), fgetws(), fread(), fscanf(), getc(), getchar(), gets(), or scanf() using  stream  that  returns
       data not supplied by a prior call to ungetc() or ungetwc().

RETURN VALUE

       Upon  successful  completion, fread() shall return the number of elements successfully read which is less
       than nitems only if a read error or end-of-file is encountered. If size or nitems  is  0,  fread()  shall
       return 0 and the contents of the array and the state of the stream remain unchanged. Otherwise, if a read
       error  occurs, the error indicator for the stream shall be set,    and errno shall be set to indicate the
       error.

ERRORS

       Refer to fgetc() .

       The following sections are informative.

EXAMPLES

   Reading from a Stream
       The following example reads a single element from the fp stream into the array pointed to by buf.

              #include <stdio.h>
              ...
              size_t bytes_read;
              char buf[100];
              FILE *fp;
              ...
              bytes_read = fread(buf, sizeof(buf), 1, fp);
              ...

APPLICATION USAGE

       The ferror() or feof() functions must be used to distinguish between an error condition  and  an  end-of-
       file condition.

       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

       feof()  ,  ferror()  ,  fgetc()  ,  fopen()  , getc() , gets() , scanf() , 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 .

IEEE/The Open Group                                   2003                                              FREAD(P)