Compilare: user.c: In function ‘qsort’: user.c:15:5: warning: implicit declaration of function ‘rand’ [-Wimplicit-function-declaration] int pivot = A[l + rand() % (r - l)], ^ user.c: In function ‘main’: user.c:40:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("algsort.out", "w", stdout); ^ user.c:42:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.c:44:34: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] for (i = 0; i < N; ++i) scanf("%d", &A[i]); ^