/in/foo.cc: In function 'int main()':
/in/foo.cc:21:13: error: 'token' was not declared in this scope
     while ((token = strtok_r(token, " ", &next_token))!= NULL) {
             ^~~~~
/in/foo.cc:21:43: error: 'next_token' was not declared in this scope
     while ((token = strtok_r(token, " ", &next_token))!= NULL) {
                                           ^~~~~~~~~~