foo.cc: In function ‘int converts(std::string, int*)’:
foo.cc:8:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    8 |         for(int i=1;i<=s.size();i++)
      |                     ~^~~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:34:39: error: expected ‘;’ before ‘；’
   34 |         while(len>1&&ans[len]==0)len--；
      |                                       ^~
      |                                       ;