Compilare: user.c: In function ‘main’: user.c:6:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("insula.in","r",stdin),freopen("insula.out","w",stdout),scanf("%d",&t); ^ user.c:6:43: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("insula.in","r",stdin),freopen("insula.out","w",stdout),scanf("%d",&t); ^ user.c:6:74: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("insula.in","r",stdin),freopen("insula.out","w",stdout),scanf("%d",&t); ^ user.c:8:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%f",&r),printf("%.3f\n",floor(1000/sqrt(r*r+1))/1000.0); ^