foo.cc: In function ‘int main()’:
foo.cc:14:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   14 |     while(i<a->size()&&j<b->size())
      |           ~^~~~~~~~~~
foo.cc:14:25: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   14 |     while(i<a->size()&&j<b->size())
      |                        ~^~~~~~~~~~
foo.cc:16:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   16 |     while(i<a->size())c->push_back((*a)[i++]);
      |           ~^~~~~~~~~~
foo.cc:17:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   17 |     while(j<b->size())c->push_back((*b)[j++]);
      |           ~^~~~~~~~~~