void fucn(string a, string b, string c) { string ret = ""; ret = System.String.Concat( ret, a ); ret = System.String.Concat( ret, '\0' ); ret = System.String.Concat( ret, b ); ret = System.String.Concat( ret, '\0' ); ret = System.String.Concat( ret, c ); ret = System.String.Concat( ret, '\0' ); ret = System.String.Concat( ret, '\0' ); } func("aaa","bbb","ccc");