Hi,
pls check this
DATA:
v_count TYPE i,
v_namelen TYPE i,
lv_variable TYPE string VALUE 'KIRAN!$%^'.
v_count = 0.
v_namelen = strlen( lv_variable ).
DO v_namelen TIMES.
IF lv_variable+v_count(1) NA sy-abcde ."or lv_variable+v_count(1) NA space .
REPLACE lv_variable+v_count(1) WITH '#' INTO lv_variable.
endif.
v_count = v_count + 1.
ENDDO.