FSEEK(3)                            Linux Programmer's Manual                            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, const 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, respec‐
       tively.   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  indicator  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 reposi‐
       tion a text stream.

RETURN VALUE
       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
       errno is set to indicate 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.   Or:  the
              resulting file offset would be negative.

       The  functions  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).

CONFORMING TO
       C89, C99.

SEE ALSO
       lseek(2), fseeko(3)

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



GNU                                         2014-05-28                                   FSEEK(3)