Compilare: user.c: In function ‘main’: user.c:11:21: warning: operation on ‘u[i]’ may be undefined [-Wsequence-point] u[i]^=v[i]^=u[i]^=v[i]; ^ user.c:4:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("radixsort.in","r",stdin),freopen("radixsort.out","w",stdout), ^ user.c:4:46: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("radixsort.in","r",stdin),freopen("radixsort.out","w",stdout), ^ user.c:5:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&a,&b,&c),v[0]=b%c,r=sizeof(v[0]); ^