rem: unsigned int i;
add: enum Char_class i;
context: look_up_char_class (const unsigned char *class_str, size_t len){  unsigned int i;  for (i = 0; i < N_CHAR_CLASSES; i++)    if (strncmp ((const char *) class_str, char_class_name[i], len) == 0	&& strlen (char_class_name[i]) == len)      return (enum Char_class) i;  return CC_NO_CLASS;}