foo.cc: In function 'int main()':
foo.cc:22:7: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |   if(i<s.length())
      |      ~^~~~~~~~~~~
foo.cc:25:12: warning: comparison of integer expressions of different signedness: 'int' and 'const size_type' {aka 'const long unsigned int'} [-Wsign-compare]
   25 |    if(index!=s.npos)

[Hydro](https://hydro.ac)提供评测服务