fseek, rewind, ftell

Purpose

     Repositions the file pointer of a stream.

Library

     Standard I/O Library (libc.a)

Syntax

     #include <stdio.h>

     int fseek (stream, offset, whence)        void rewind (stream)
     FILE *stream;                             FILE *stream;
     long offset;
     int whence;                               long ftell (stream)
                                               FILE *stream;
     Description

     The fseek subroutine sets the  position of the next input
     or output  operation on the  I/O stream specified  by the
     stream parameter.  The position  of the next operation is
     determined by  the offset parameter, which  can be either
     positive or negative.

     The  fseek subroutine  sets the  file pointer  associated
     with the specified stream as follows:

     o   If the whence  parameter is 0, the pointer  is set to
         the value of the offset parameter.

     o   If the whence  parameter is 1, the pointer  is set to
         its  current location  plus the  value of  the offset
         parameter.

     o   If the whence  parameter is 2, the pointer  is set to
         the size  of the  file plus the  value of  the offset
         parameter.

     The fseek  subroutine fails if  attempted on a  file that
     has not  been opened  using fopen.  In  particular, fseek
     cannot be  used on a terminal,  or on a file  opened with
     popen.

     Upon successful  completion, fseek returns a  value of 0.
     If fseek fails, a nonzero value is returned.

     The  rewind subroutine  is equivalent  to fseek  (stream,
     (long) 0, 0), except that it does not return a value.

     The fseek and rewind subroutines  undo any effects of the
     ungetc subroutine.

     After an fseek or a rewind,  the next operation on a file
     opened for update can be either input or output.

     The ftell  subroutine returns  the offset of  the current
     byte  relative to  the beginning  of the  file associated
     with the named stream.

     Related Information

     In this  book:  "lseek,"  "fopen, freopen,  fdopen," and
     "standard i/o library."