//===============================================
    function edit(){
        $config = array(
                        'upload_path'=>'./uploads',
                        'allowed_types'=>'jpg|png|jpeg',
                        'max_size'=>2086
                        );

        $id = $this->input->post('id');
        $judul = $this->input->post('judul');
        $tebal = $this->input->post('tebal');
        $penerbit = $this->input->post('penerbit');
        $data_kode = array('id'=>$id);
        $foto = $this->db->get_where('tb_buku',$data_kode);

    if($foto->num_rows()>0){
      $pros=$foto->row();
      $name=$pros->gambar;

      if(file_exists($lok=FCPATH.'/uploads/'.$name)){
        unlink($lok);
      }
      if(file_exists($lok=FCPATH.'/uploads/thumbnail/'.$name)){
        unlink($lok);
      }}

        $this->load->library('upload',$config);

        if($this->upload->do_upload('gambar')){

        $finfo = $this->upload->data();
        $nama_foto = $finfo['file_name'];

        $data_buku = array(
                            'judul'=>$judul,
                            'tebal'=>$tebal,
                            'penerbit'=>$penerbit,
                            'gambar'=>$nama_foto
                            );

        $config2 = array(
                'source_image'=>'uploads/'.$nama_foto,
                'image_library'=>'gd2',
                'new_image'=>'uploads/thumbnail',
                'maintain_ratio'=>true,
                'width'=>150,
                'height'=>200
            );

        $this->load->library('image_lib',$config2);
        $this->image_lib->resize();

        }else{
        $data_buku = array(
                            'judul'=>$judul,
                            'tebal'=>$tebal,
                            'penerbit'=>$penerbit
                            );

        }

        $this->M_buku->edit_data($data_kode,$data_buku);
        redirect('C_buku');
    }