Compilare: user.cpp: In function ‘int main()’: user.cpp:11:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &n); ^ user.cpp:13:27: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &v[i]); ^ user.cpp:42:3: warning: ‘flag’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (flag == -1) { ^ user.cpp:45:65: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] fprintf(f, "%d %d\n", n - i, !flag ? v[i] - x : x - v[i - 1]); ^