Eroare de compilare: user.c: In function ‘main’: user.c:10:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(IN, "r", stdin); ^ user.c:11:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(OUT, "w", stdout); ^ user.c:13:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^ /tmp/ccil7CpM.o: In function `main': user.c:(.text.startup+0x65): undefined reference to `_a' user.c:(.text.startup+0x6b): undefined reference to `_b' /tmp/ccil7CpM.o: In function `endwhile': user.c:(.text.startup+0x89): undefined reference to `_d' collect2: error: ld returned 1 exit status