1_Static_assert(__builtin_isdigit('0')); 2_Static_assert(__builtin_isdigit('9')); 3 4_Static_assert(!__builtin_isdigit(0)); 5_Static_assert(!__builtin_isdigit(' ')); 6_Static_assert(!__builtin_isdigit('z')); 7 8/* 9 * check-name: builtin_isdigit 10 */ 11