Compilare: user.c:2:1: warning: data definition has no type or storage class [enabled by default] a,b;main(){freopen("tabela.in","r",stdin);freopen("tabela.out","w",stdout);scanf("%d %d",&a,&b);printf("%d",--a^--b);} ^ user.c:2:1: warning: type defaults to ‘int’ in declaration of ‘a’ [enabled by default] user.c:2:3: warning: type defaults to ‘int’ in declaration of ‘b’ [enabled by default] a,b;main(){freopen("tabela.in","r",stdin);freopen("tabela.out","w",stdout);scanf("%d %d",&a,&b);printf("%d",--a^--b);} ^ user.c:2:5: warning: return type defaults to ‘int’ [enabled by default] a,b;main(){freopen("tabela.in","r",stdin);freopen("tabela.out","w",stdout);scanf("%d %d",&a,&b);printf("%d",--a^--b);} ^ user.c: In function ‘main’: user.c:2:19: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] a,b;main(){freopen("tabela.in","r",stdin);freopen("tabela.out","w",stdout);scanf("%d %d",&a,&b);printf("%d",--a^--b);} ^ user.c:2:50: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] a,b;main(){freopen("tabela.in","r",stdin);freopen("tabela.out","w",stdout);scanf("%d %d",&a,&b);printf("%d",--a^--b);} ^ user.c:2:81: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] a,b;main(){freopen("tabela.in","r",stdin);freopen("tabela.out","w",stdout);scanf("%d %d",&a,&b);printf("%d",--a^--b);} ^