Compilare: user.cpp: In function ‘std::vector<int> multiply(std::vector<int>, std::vector<int>)’: user.cpp:22:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++) { ^ user.cpp:24:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < b.size() || t > 0; j++) { ^ user.cpp:25:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(c.size() <= i + j) ^ user.cpp:27:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j < b.size()) ^ user.cpp: In function ‘int main()’: user.cpp:57:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a.size() - i - 1; i++) ^ user.cpp:59:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < b.size() - i - 1; i++) ^ user.cpp:46:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d " ,&fr[i]); ^