foo.cc: In function ‘int main()’:
foo.cc:12:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   12 |         while (idx != -1&&idx<t.size())
      |                           ~~~^~~~~~~~~
foo.cc:18:45: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   18 |                         for (int i = pre; i < t.size(); i++) cout << t[i];
      |                                           ~~^~~~~~~~~~