Compilare: user.c:2:1: warning: return type defaults to ‘int’ [enabled by default] main(){int a,b;freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);} ^ user.c: In function ‘main’: user.c:2:23: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] main(){int a,b;freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);} ^ user.c:2:55: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] main(){int a,b;freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);} ^ user.c:2:87: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] main(){int a,b;freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);scanf("%d%d",&a,&b);printf("%d",a+b);} ^