How to create a Dynamic Internal Table or Array?

Can you create an internal table dynamically? (at run time)

Yes , you can create a Dynamic Internal table .Just chek out this program .

type-pools : abap.
field-symbols: <dyn_table> type standard table,
<dyn_wa>,
<dyn_field>.
data: dy_table type ref to data,
dy_line type ref to data,
xfc type lvc_s_fcat,
ifc type lvc_t_fcat.
selection-screen begin of block b1 with frame.
parameters: p_table(30) type c default 'T001'.
selection-screen end of block b1.
start-of-selection.
perform get_structure.
perform create_dynamic_itab. **********Creates a dyanamic internal table**********
perform get_data.
perform write_out.
form get_structure.
data : idetails type abap_compdescr_tab,
xdetails type abap_compdescr.
data : ref_table_des type ref to cl_abap_structdescr.
* Get the structure of the table.
ref_table_des ?=
cl_abap_typedescr=>describe_by_name( p_table ).
idetails[] = ref_table_des->components[].
loop at idetails into xdetails.
clear xfc.
xfc-fieldname = xdetails-name .
xfc-datatype = xdetails-type_kind.
xfc-inttype = xdetails-type_kind.
xfc-intlen = xdetails-length.
xfc-decimals = xdetails-decimals.
append xfc to ifc.
endloop.
endform.
form create_dynamic_itab.
* Create dynamic internal table and assign to FS
call method cl_alv_table_create=>create_dynamic_table
exporting
it_fieldcatalog = ifc
importing
ep_table = dy_table.
assign dy_table->* to <dyn_table>.
* Create dynamic work area and assign to FS
create data dy_line like line of <dyn_table>.
assign dy_line->* to <dyn_wa>.
endform.

form get_data.
* Select Data from table.
select * into table <dyn_table>
from (p_table).
endform.
Write out data from table.
loop at <dyn_table> into <dyn_wa>.
do.
assign component sy-index
of structure <dyn_wa> to <dyn_field>.
if sy-subrc 0.
exit.
endif.
if sy-index = 1.
write:/ <dyn_field>.
else.
write: <dyn_field>.
endif.
enddo.
endloop.



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REPORT ZCLUST1 .
*
* Example: how to create a dynamic internal table
*
* The dynamic internal table stucture
DATA: BEGIN OF STRUCT OCCURS 10,
FILDNAME(8) TYPE C,
ABPTYPE TYPE C,
LENGTH TYPE I,
END OF STRUCT.

* The dynamic program source table
DATA: BEGIN OF INCTABL OCCURS 10,
LINE(72),
END OF INCTABL.

DATA: LNG TYPE I, TYPESRTING(6).

* Sample dynamic internal table stucture
STRUCT-FILDNAME = 'field1'. STRUCT-ABPTYPE = 'c'. STRUCT-LENGTH = '6'.
APPEND STRUCT. CLEAR STRUCT.

STRUCT-FILDNAME = 'field2'. STRUCT-ABPTYPE = 'd'.
APPEND STRUCT. CLEAR STRUCT.

STRUCT-FILDNAME = 'field3'. STRUCT-ABPTYPE = 'i'.
APPEND STRUCT. CLEAR STRUCT.

* Create the dynamic internal table definition in the dyn. program
INCTABL-LINE = 'program zdynpro.'. APPEND INCTABL.
INCTABL-LINE = 'data: begin of dyntab occurs 10,'. APPEND INCTABL.

LOOP AT STRUCT.
INCTABL-LINE = STRUCT-FILDNAME.
LNG = STRLEN( STRUCT-FILDNAME ).

IF NOT STRUCT-LENGTH IS INITIAL .
TYPESRTING(1) = '('.
TYPESRTING+1 = STRUCT-LENGTH.
TYPESRTING+5 = ')'.
CONDENSE TYPESRTING NO-GAPS.
INCTABL-LINE+LNG = TYPESRTING.
ENDIF.

INCTABL-LINE+15 = 'type '.
INCTABL-LINE+21 = STRUCT-ABPTYPE.
INCTABL-LINE+22 = ','.
APPEND INCTABL.
ENDLOOP.
INCTABL-LINE = 'end of dyntab. '.
APPEND INCTABL.

* Create the code processes the dynamic internal table
INCTABL-LINE = ' '. APPEND INCTABL.
INCTABL-LINE = 'dyntab-field1 = ''aaaaaa''.'. APPEND INCTABL.
INCTABL-LINE = 'dyntab-field1 = ''19970814''.'. APPEND INCTABL.
INCTABL-LINE = 'dyntab-field1 = 1.'. APPEND INCTABL.
INCTABL-LINE = 'append dyntab.'. APPEND INCTABL.
INCTABL-LINE = ' '. APPEND INCTABL.
INCTABL-LINE = 'loop at dyntab.'. APPEND INCTABL.
INCTABL-LINE = 'write: / dyntab.'. APPEND INCTABL.
INCTABL-LINE = 'endloop.'. APPEND INCTABL.

* Create and run the dynamic program
INSERT REPORT 'zdynpro'(001) FROM INCTABL.
SUBMIT ZDYNPRO.



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or Just try out this simpler dynamic internal tables

DATA: itab TYPE STANDARD TABLE OF spfli,
wa LIKE LINE OF itab.

DATA: line(72) TYPE c,
list LIKE TABLE OF line(72).

START-OF-SELECTION.
*line = ' CITYFROM CITYTO '.
line = ' AIRPTO '.
APPEND line TO list.

SELECT DISTINCT (list)
INTO CORRESPONDING FIELDS OF TABLE itab
FROM spfli.

IF sy-subrc EQ 0.
LOOP AT itab INTO wa.
* WRITE: / wa-cityfrom, wa-cityto.
WRITE :/ wa-airpto.
ENDLOOP.
ENDIF.