Read / write file with ABAP

Read file :

  DATA : lo_error  TYPE REF TO cx_root,
         lw_error  TYPE string.

*                    ENCODING DEFAULT = ANSCII on main SAP system.
  OPEN DATASET lw_fullname FOR INPUT IN TEXT MODE ENCODING DEFAULT. 
  IF sy-subrc <> 0.
    " Manage erreur
  ENDIF.

* For each line
  DO.
*   Read line
    TRY.
          READ DATASET lw_fullname INTO lw_string.

       CATCH cx_sy_conversion_codepage INTO lo_error.  " En cas d'erreur d`encodage, 
        lw_error = lo_error->get_text( ).              " fichier en UTF-8 alors que 
        WRITE / lw_error.                              " lu en mode défaut par exemple
        EXIT.       
    ENDTRY.

    IF sy-subrc = 0.
      " Treat data
      APPEND lw_string TO li_string.
    ELSE.
      EXIT.
    ENDIF.

  ENDDO.
  
  CLOSE DATASET lw_fullname.