Wroking With Filed Symbols

Many People affraid in writing the code with field symbols.
It's very simple. Field symbols are directly point to memory. So, If we modified the data in the field symbols it will directly effect to the memory.
Syntax : FIELD-SYMBOLS : TYPE .
Use ASSIGNIG statement to use field symbols.
Eg:
Declaration:
TYPES : BEGIN OF ty_itab,
A type N,
B type i,
C type i,
D type i,
END OF ty_itab.

FIELD-SYMBOLS : < wa > type ty_itab.
data : itab type standrad table of ty_itab.
now we can use this in the program.
Requirement is to calculate the value of d value from the itab table.
d = b + c.
LOOP AT itab ASSIGNING < wa >.
< wa >-d = < wa >-b + < wa >-c.
*Here no need to write modify statement. Beacuse < wa >is a field symbol and it is pointing to memory of itab. If you modified < wa >, It automatically effected to the internal table itab.
ENDLOOP.