Compilare: user.c: In function ‘main’: user.c:3:27: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] int main(){int a,b;freopen("C.in","r",stdin);freopen("C.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);return 0;} ^ user.c:3:53: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] int main(){int a,b;freopen("C.in","r",stdin);freopen("C.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);return 0;} ^ user.c:3:79: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] int main(){int a,b;freopen("C.in","r",stdin);freopen("C.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);return 0;} ^