foo.cc: In member function 'void BigNum::init(std::string&, std::string&)':
foo.cc:54:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |         for(int i=0;i<x.size();i++)
      |                     ~^~~~~~~~~
foo.cc:56:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |         for(int i=0;i<y.size();i++)
      |                     ~^~~~~~~~~
foo.cc: In member function 'std::vector<int> BigNum::Add()':
foo.cc:70:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   70 |         for(int i=0; i<a.size(); i++)
      |                      ~^~~~~~~~~
foo.cc: In member function 'std::vector<int> BigNum::Sub()':
foo.cc:89:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |         for(int i=0; i<a.size(); i++)
      |                      ~^~~~~~~~~
foo.cc: In member function 'std::vector<int> BigNum::Div()':
foo.cc:131:5: warning: no return statement in function returning non-void [-Wreturn-type]
  131 |     }
      |     ^
foo.cc: In member function 'std::vector<int> BigNum::Mod()':
foo.cc:136:5: warning: no return statement in function returning non-void [-Wreturn-type]
  136 |     }
      |     ^
foo.cc: In member function 'void BigNum::Print(std::vector<int>&)':
foo.cc:139:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  139 |         for(int i=0; i<ve.size(); i++)
      |                      ~^~~~~~~~~~

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