下列对结构类型变量的定义中不正确的是() A: struct{longintnum;charname[20];charsex;charaddr[20];}student;structstudentstd1; B: #defineSTUDENT structstudentSTUDENT{longintnum;charname[20];charsex;charaddr[20];}std1; C: struct{longintnum;charname[20];charsex;charaddr[20];}std1; D: struct student{longintnum;charname[20];charsex;charaddr[20];}std1;

下面程序是从键盘输入学号,然后输出学号中百位数字是3的学号,输入0时结束循环，请填空。main(){longintnum;scanf("%ld",&num);do{if(______)printf("%ld",num);scanf("%ld",&num);}while(______);}