data ref

[Former Member]

Please read this code & answer the following questions

REPORT demo_data_reference.

TYPES: BEGIN OF t_struct,
         col1 TYPE i,
         col2 TYPE i,
       END OF t_struct.
DATA: dref1 TYPE REF TO data,
      dref2 TYPE REF TO data.
FIELD-SYMBOLS: <fs1> TYPE t_struct,
               <fs2> TYPE i.
CREATE DATA dref1 TYPE t_struct.
ASSIGN dref1->* TO <fs1>.
<fs1>-col1 = 1.
<fs1>-col2 = 2.
dref2 = dref1.
ASSIGN dref2->* TO <fs2> CASTING.
WRITE / <fs2>.
GET REFERENCE OF <fs1>-col2 INTO dref2.
ASSIGN dref2->* TO <fs2>.
WRITE / <fs2>.

The list output is:

1

2

This example declares two data reference variables dref1 and dref2. dref1is used to create a structured dynamic data object. This is dereferenced with the field symbol <fs1>, and values are then assigned to it. dref1 is assigned to dref2. dref2then points to the structured data object. When dref2 is dereferenced, it is cast to the elementary type i of field symbol <fs2>. Its first component is assigned to the field symbol. GET REFERENCE is then used to get a reference to the second component not the structured data object in dref2. It is dereferenced without casting.

http://help.sap.com/saphelp_nw2004s/helpdata/en/16/0dce0a0cf711d3b9360000e8353423/frameset.htm

Q1] In the GET REFERENCE statement are we assigning twice, as “dref2” has already been assigned in the statement

“ DREF2 = DREF1 .”

Q2] What is CASTING?

Q3 ] WHAT IS DEREFERENCING?

[seshatalpasai_madala]

Hi.

Q1] In the GET REFERENCE statement are we assigning twice, as “dref2” has already been assigned in the statement.

Here you are asigning the memory address of <fs1>->col2. You are just replacing the memory address it was previously reffering to with a new memory addrress.

Q2] What is CASTING?

With the addition CASTING you are saying that assign the TYPE of the data that is there in the dref2->* to the FIELD-SYMBOL <fs2>.

Q3 ] WHAT IS DEREFERENCING?

Dereferencing is getting the value from the Memory address to which we have reference it is done using ->* operator.

Regards,

Sesh