Compilare: user.cpp: In function ‘std::vector<int> add(std::vector<int>, std::vector<int>)’: user.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i < a.size()) ^ user.cpp:15:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i < b.size()) ^ user.cpp: In function ‘std::vector<int> multiply(std::vector<int>, int)’: user.cpp:27:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size() || t > 0; i++) { ^ user.cpp:28:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == a.size()) ^ user.cpp: In function ‘std::vector<int> dif(std::vector<int>, std::vector<int>)’: user.cpp:43:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++) { ^ user.cpp:46:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i < b.size()) { ^ user.cpp: In function ‘int main()’: user.cpp:70:43: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d %d %d %d " ,&l,&b,&p,&q); ^