fseek(3S)                                                  fseek(3S)


       NAME
             fseek, rewind, ftell - reposition a file pointer in a stream

       SYNOPSIS
             #include <stdio.h>
             int fseek(FILE *stream, long offset, int ptrname);
             void rewind(FILE *stream);
             long ftell(FILE *stream);

       DESCRIPTION
             fseek sets the position of the next input or output operation
             on the stream [see intro(3)].  The new position is at the
             signed distance offset bytes from the beginning, from the
             current position, or from the end of the file, according to a
             ptrname value of SEEK_SET, SEEK_CUR, or SEEK_END (defined in
             stdio.h) as follows:

             SEEK_SET    set position equal to offset bytes.

             SEEK_CUR    set position to current location plus offset.

             SEEK_END    set position to EOF plus offset.

             fseek allows the file position indicator to be set beyond the
             end of the existing data in the file.  If data is later
             written at this point, subsequent reads of data in the gap
             will return zero until data is actually written into the gap.
             fseek, by itself, does not extend the size of the file.

             rewind (stream) is equivalent to:

                   (void) fseek (stream, 0L, SEEK_SET);

             except that rewind also clears the error indicator on stream.

             fseek and rewind clear the EOF indicator and undo any effects
             of ungetc on stream.  After fseek or rewind, the next
             operation on a file opened for update may be either input or
             output.

             If stream is writable and buffered data has not been written
             to the underlying file, fseek and rewind cause the unwritten
             data to be written to the file.





                           Copyright 1994 Novell, Inc.               Page 1

      fseek(3S)                                                  fseek(3S)


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

         Errors
            fseek returns -1 for improper seeks, otherwise zero.  An
            improper seek can be, for example, an fseek done on a file
            that has not been opened via fopen; in particular, fseek may
            not be used on a terminal or on a file opened via popen.
            After a stream is closed, no further operations are defined on
            that stream.

      REFERENCES
            fopen(3S), lseek(2), popen(3S), stdio(3S), ungetc(3S),
            write(2)

      NOTICES
            Although on the UNIX system an offset returned by ftell is
            measured in bytes, and it is permissible to seek to positions
            relative to that offset, portability to non-UNIX systems
            requires that an offset be used by fseek directly.  Arithmetic
            may not meaningfully be performed on such an offset, which is
            not necessarily measured in bytes.


























                          Copyright 1994 Novell, Inc.               Page 2