How to handler special characters

CREATE OR REPLACE FUNCTION strip_special_character ( in_string IN varchar2,in_chars IN varchar2 DEFAULT NULL) RETURN varchar2 IS
TAB CHAR(1) := chr(9);
double_quote char( 1 ) := chr(34);
single_quote char( 1 ) := chr(39);
mask varchar2( 80 ) := '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
v_special_chars varchar2( 80 ) := '`~^\'double_quotesingle_quotetab;
begin
IF in_chars IS NOT NULL then
v_special_chars := in_chars;
end
IF; RETURN translate( in_string, mask v_special_chars, mask );
exception when others then RETURN in_string;
end strip_special_character;