foo.cc: In function ‘bool b(std::string)’:
foo.cc:5:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    5 |         for(int i=0;i<n.size();i++)
      |                     ~^~~~~~~~~
foo.cc: In function ‘bool o(std::string)’:
foo.cc:11:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   11 |         for(int i=0;i<n.size();i++)
      |                     ~^~~~~~~~~
foo.cc:11:9: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation]
   11 |         for(int i=0;i<n.size();i++)
      |         ^~~
foo.cc:13:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
   13 |                 return 1;
      |                 ^~~~~~
foo.cc: In function ‘bool d(std::string)’:
foo.cc:17:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   17 |         for(int i=0;i<n.size();i++)
      |                     ~^~~~~~~~~
foo.cc: In function ‘bool h(std::string)’:
foo.cc:23:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   23 |         for(int i=0;i<n.size();i++)
      |                     ~^~~~~~~~~