Little tip to get the nr of elements in a local structure using RTTI

Question

sometimes you need to know the number of elements in a structure for manpulating data
for example you might need to convert the elements in an internal table to a special file format such as "field","field",......"field".
instead of something like this where  you have counted the number of elements in your structure
you can obtain the number of elements dynamically. This saves changing the code each time you change the structure and can avoid errors.
data: zstring type string
data: zstring1 type string.
lv_index = 1.
    WHILE lv_index LE 47. 
      .CLEAR zstring.
      ASSIGN COMPONENT lv_index OF STRUCTURE  your_ structure  TO  <fsa>.
      CONCATENATE '"' <fsa> '"' INTO zstring.
      CONCATENATE zstring1 zstring INTO zstring1.
      CONCATENATE  zstring1 ',' INTO zstring1.
      lv_index = lv_index + 1.
      CLEAR zstring.
    endwhile
lv_index = 48.
    ASSIGN COMPONENT lv_index OF STRUCTURE wa_interface_contracts TO  <fsa>.
    CONCATENATE '"' <fsa> '"' INTO zstring.
    CONCATENATE zstring1 zstring INTO zstring1.
    CONDENSE zstring1.    "Left align all data fields within the string
    APPEND zstring1 TO ta_string1.
    CLEAR zstring.
    CLEAR zstring1.
    lv_index = 1.
Using the RTTI
DATA lr_rtti_struc TYPE REF TO cl_abap_structdescr .
DATA: zog    LIKE LINE OF lr_rtti_struc->components .
DATA:  zogt                    LIKE TABLE OF zog,
  CREATE DATA dref TYPE your_structure
  ASSIGN dref->* TO <fs>.
  lr_rtti_struc ?= cl_abap_structdescr=>describe_by_data( <fs> ).
* get the structure details into a table.
* table zogt[] contains the structure details
  zogt[]  = lr_rtti_struc->components. 
now the nr of rows in this table contains the number of elements in your structure.
cheers
jimbo

Answer 1

hi Jimbo,
why don't you start blogging?
ec