right way to declare field symbols

[Former Member]

i am new to field symbols, pls help

i want to know which is the right way of declaration ?

types: begin of typ_tab,
           vbeln  type vbap-vbeln,
           posnr type vbap-posnr,
           matnr  type vbap-matnr,
           - - - - -
          end of typ_tab.
 
data:  itab type standard table of typ_tab,
          wa  type typ_tab.
 
field-symbols: <f_t> type standard table,  
                       <f_w> type any,                or      <f_w>  like  line of typ_tab,  ??
                        <f_s> type any.
 
select  vbeln posnr  ....... into itab......
 
assign  itab to <f_t>.
assign wa  to <f_w>.
 
loop at <f_t> assigning <f_w>.
assign component 'vbeln' of structure <f_w>  to <f_s>.
write : / <f_s>.
endloop.

OR

loop at itab assigning <f_w>.  
write: / <f_w>-vbeln.
endloop.  

r these 2 statements correctt ? if so then which one  to use,  pls show with an example. wats the diff btwn above 2  types of  looping statements ?   how to use read statement on this ?

[asik_shameem]

Hello Saurajit,

Both the way are correct. And it depends on the requirement, which one to use.

<f_w> TYPE ty_tab - is TYPED field symbol - if you know TYPE before runtime you can use this. It will just work like a static work area.

<f_w> TYPE any - is not TYPED and structure of this field symbol is defined during runtime using ASSIGN statement. And fields of the structure is read by ASSIGN COMPONENT <<field name>> statement.