Compilare: user.cpp: In function ‘int main()’: user.cpp:31:32: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘std::vector<double>::size_type {aka long unsigned int}’ [-Wformat=] fprintf(fo,"%d\n", V.size()); ^ user.cpp:14:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d%lf", &n, &l); ^ user.cpp:16:134: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i = 1; i <= n; i++) fscanf(fi,"%lf%lf%lf%lf%lf", &v[i].a, &v[i].b, &v[i].k, &v[i].q, &v[i].v), c1 += v[i].a, c2 += v[i].k; ^