FSEEK(3)                       Library Routines                       FSEEK(3)




NAME

       fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream


SYNOPSIS

       #include <stdio.h>

       int fseek (FILE *stream, long offset, int whence);
       long ftell (FILE *stream);
       void rewind (FILE *stream);
       int fgetpos (FILE *stream, fpos_t *pos);
       int fsetpos (FILE *stream, fpos_t *pos);


DESCRIPTION

       The  fseek  function  sets  the  file position indicator for the stream
       pointed to by stream.  The new position, measured in bytes, is obtained
       by  adding offset bytes to the position specified by whence.  If whence
       is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset  is  relative  to
       the  start of the file, the current position indicator, or end-of-file,
       respectively.  A successful call to the fseek function clears the  end-
       of-file  indicator  for  the  stream  and  undoes  any  effects  of the
       ungetc(3) function on the same stream.

       The ftell function obtains the current value of the file position indi-
       cator for the stream pointed to by stream.

       The  rewind  function  sets  the file position indicator for the stream
       pointed to by stream to the beginning of the file.   It  is  equivalent
       to:
                   (void) fseek(stream, 0L, SEEK_SET)
       except  that  the  error  indicator for the stream is also cleared (see
       clearerr(3)).

       The fgetpos and fsetpos functions are alternate  interfaces  equivalent
       to  ftell  and fseek (with whence set to SEEK_SET), setting and storing
       the current value of the file offset into or from the object referenced
       by  pos.   On  some  non-UNIX systems an fpos_t object may be a complex
       object and these routines may be the only way to portably reposition  a
       text stream.


RETURN VALUES

       The  rewind  function  returns  no  value.  Upon successful completion,
       fgetpos, fseek, fsetpos return 0, and ftell returns the current offset.
       Otherwise, -1 is returned and the global variable errno is set to indi-
       cate the error.


ERRORS

              EBADF  The stream specified is not a seekable stream.

              EINVAL The whence argument to fseek was not SEEK_SET,  SEEK_END,
                     or SEEK_CUR.

       The  function  fgetpos, fseek, fsetpos, and ftell may also fail and set
       errno for any of the  errors  specified  for  the  routines  fflush(3),
       fstat(2), lseek(2), and malloc(3).


SEE ALSO

       lseek(2)


STANDARDS

       The  fgetpos,  fsetpos,  fseek,  ftell, and rewind functions conform to
       ANSI/C.



GNO                            15 September 1997                      FSEEK(3)

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