- XBT_VERB(" %s (state=%ld)", prev_state->get_transition()->to_cstring(), prev_state->num_);
- XBT_VERB(" %s (state=%ld)", state->get_transition()->to_cstring(), state->num_);
+ XBT_VERB(" %s (state=%ld)", prev_state->get_transition()->to_string().c_str(), prev_state->num_);
+ XBT_VERB(" %s (state=%ld)", state->get_transition()->to_string().c_str(), state->num_);