Get the Number of rows or set the number of rows dynamically (internal tab)

Question

Hi,
question pls see subject ?
Regards
sas

Answer 1

Hi,
Use the method describe_by_data of the class cl_abap_structdescr. this will give you a refernce of the class type descriptor class and you need to down cast it to a more specifc class of cl_abap_structdescr.
Once you get the correct reference, you can use the components attribute and you will get a list of all the fields of that table.
DATA: BEGIN OF line OCCURS 0,
        col1 TYPE i,
        col2(10) TYPE c,
        col3 TYPE i,
      END OF line.
FIELD-SYMBOLS : <itab_line> TYPE ANY.
DATA : BEGIN OF t_comp OCCURS 0,
        comp(5) TYPE c,
       END OF t_comp.
DATA : l_struc TYPE REF TO cl_abap_structdescr.
DATA : l_typedesc TYPE REF TO cl_abap_typedescr.
DATA : lt_comp TYPE abap_compdescr_tab,
       w_comp LIKE LINE OF lt_comp.
line-col1 = 11.line-col2 = 'SAP'.line-col3 = 33.
APPEND line.
line-col1 = 44.line-col2 = 'P.I.'.line-col3 = 66.
APPEND line.
ASSIGN line TO <itab_line>.  " Refer of the table is passed to the field symbol
*Call the static method of the structure descriptor describe_by_data
CALL METHOD cl_abap_structdescr=>describe_by_data
  EXPORTING
    p_data      = <itab_line>
  RECEIVING
    p_descr_ref = l_typedesc.
*The method returns a reference of  a type descriptor class therefore
*we need to Cast the type descriptor to a more specific class i.e
*Structure Descriptor.
l_struc ?= l_typedesc.
*Use the Attribute COMPONENTS of the structure Descriptor class to get
*the field names of the structure
lt_comp = l_struc->components.
data l_components.
describe table lt_comp lines l_compoents.  " count the components
Write : 'Table has ', l_component, ' fields.'.
Hope this helps.
regards,
Advait