abap-补零函数 上传函数

CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
      EXPORTING
        input  = GS_itab-aktnr
      IMPORTING

        output = GS_itab-aktnr.

CALL FUNCTION 'GUI_UPLOAD'
    EXPORTING
      filename                      = dfile
*   FILETYPE                      = 'BIN'
      has_field_separator           = 'X'
*   HEADER_LENGTH                 = 0
*   READ_BY_LINE                  = 'X'
*   DAT_MODE                      = ' '
*   CODEPAGE                      = '8400'
*   IGNORE_CERR                   = ABAP_TRUE
*   REPLACEMENT                   = '#'
*   CHECK_BOM                     = ' '
*   VIRUS_SCAN_PROFILE            = VIRUS_SCAN_PROFILE
*   NO_AUTH_CHECK                 = ' '
* IMPORTING
*   FILELENGTH                    = FILELENGTH
*   HEADER                        = HEADER
    TABLES
      data_tab                      = GI_itab
   EXCEPTIONS
     file_open_error               = 1
     file_read_error               = 2
     no_batch                      = 3
     gui_refuse_filetransfer       = 4
     invalid_type                  = 5
     no_authority                  = 6
     unknown_error                 = 7
     bad_data_format               = 8
     header_not_allowed            = 9
     separator_not_allowed         = 10
     header_too_long               = 11
     unknown_dp_error              = 12
     access_denied                 = 13
     dp_out_of_memory              = 14
     disk_full                     = 15
     dp_timeout                    = 16
            .