Delete Before simpul pointer dalam pascal

 Delete Before

Yaitu menghapus data di sebelah kanan dari simpul

program dlete;

{$APPTYPE CONSOLE}

uses

  SysUtils;

type

   point = ^recKar ;

   reckar = record

              id_mhs : string ;

              nama : string ;

              prodi : string ;

              semester : integer ;

              next,prev : point;

            end;

var

  head,now,tail : point ;

  jawab : char ;

  no : byte ;

procedure insertAfter ;      // insert After

begin

  new(now) ;

  if head =nil then

     begin

       head := now ;

       tail := now ;

       head^.prev := nil ;

       tail^.prev := nil ;

     end

  else

    begin

      tail^.next := now ;

      now^.prev := tail ;

      tail := now ;

      tail^.next := nil ;

    end;

end;

procedure deleteBefore ;

begin

  now := head ;

  if now <> tail then

    begin

      head := now^.next ;

      head^.prev := nil ;

    end

  else

    begin

      tail := nil ;

      head := nil ;

    end;

    if now <> nil then Dispose(now) ;

end;

begin

  writeln('DATA MAHASISWA');

  writeln('__________________________');

  writeln ;

  repeat

     insertAfter ;

      write('ID MAHASISWA :'); readln(now^.id_mhs);

      write('NAMA         :'); readln(now^.nama);

      write('PRODI        :'); readln(now^.prodi);

      write('SEMESTER     :'); readln(now^.semester);

      writeln ;

      write('Apakah ingin isi data lagi (Y/T)?  ');readln(jawab);

      writeln ;

  until upcase(jawab) ='T' ;

  writeln ;

  writeln('DATA MAHASISWA');

  writeln('__________________________');

  writeln ;

  no := 1 ;

  now := head ;

  while now <> nil do

    begin

      writeln (No,'. ID MAHASISWA :',Now^.id_mhs) ;

      writeln ('   NAMA           :',Now^.nama) ;

      writeln ('   PRODI          :',Now^.prodi) ;

      writeln ('   SEMESTER       :',Now^.semester) ;

      writeln ;

      inc(no) ;      

   now := now^.next ;  

    end;

  write('Apakah anda ingin menghapus Data (Y/T)? : ');Readln(jawab);

  if UpCase(jawab)='Y' then deleteBefore ;

  writeln ;

  writeln('DATA MAHASISWA');

  writeln('__________________________');

  writeln ;

  no := 1 ;

  now := head ;

  while now <> nil do

    begin

      writeln (No,'. ID MAHASISWA :',Now^.id_mhs) ;

      writeln ('   NAMA :',Now^.nama) ;

      writeln ('   PRODI :',Now^.prodi) ;

      writeln ('   SEMESTER :',Now^.semester) ;

      writeln ;

      inc(no) ;   

      now := now^.next ;  

    end;

  readln ;

end.