FSEEK(3S)            INTERACTIVE UNIX System            FSEEK(3S)



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

          SYNOPSIS
               #include <stdio.h>
               #include <unistd.h>

               int fseek (stream, offset, ptrname)
               FILE *stream;
               long offset;
               int ptrname;

               void rewind (stream)
               FILE *stream;

               long ftell (stream)
               FILE *stream;

          DESCRIPTION
               The fseek function sets the position of the next input or
               output operation on the stream.  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 as
               ptrname has the value 0, 1, or 2, which is defined in the
               <unistd.h> header file as follows:

                    Name      Description
                    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.

               Rewind(stream) is equivalent to fseek(stream, 0L, 0), except
               that no value is returned.

               fseek and rewind undo any effects of ungetc(3S).

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

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

          SEE ALSO
               lseek(2), fopen(3S), popen(3S), stdio(3S), ungetc(3S).

          DIAGNOSTICS
               The fseek function returns non-zero for improper seeks, oth-
               erwise zero.  An improper seek can be, for example, an fseek
               done on a file that has not been opened via fopen; in par-
               ticular, fseek may not be used on a terminal or on a file
               opened via popen(3S).

          WARNING


          Rev. C Software Development Set                            Page 1

          FSEEK(3S)            INTERACTIVE UNIX System            FSEEK(3S)



               Although on the UNIX system an offset returned by ftell is
               measured in bytes, and it is permissible to seek to posi-
               tions relative to that offset, portability to non-UNIX sys-
               tems 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.

















































          Rev. C Software Development Set                            Page 2