Compilare: user.c: In function ‘main’: user.c:16:11: warning: type defaults to ‘int’ in declaration of ‘v’ [enabled by default] register v; ^ user.c:24:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("piramida.in", "r", stdin); ^ user.c:25:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.c:40:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("piramida.out", "w", stdout); ^