/in/foo.cc:6:11: error: expected identifier before ';' token
  int class;
           ^
/in/foo.cc:6:11: error: multiple types in one declaration
/in/foo.cc:6:11: error: declaration does not declare anything [-fpermissive]
/in/foo.cc: In function 'int main()':
/in/foo.cc:15:18: error: 'scanf_s' was not declared in this scope
  scanf_s("%d", &N);
                  ^
/in/foo.cc:21:52: error: expected unqualified-id before 'class'
    scanf_s("%d %d %c %c %d",&stu[i]->avg, &stu[i]->class, &stu[i]->leader, &stu[i]->west, &stu[i]->num);
                                                    ^
/in/foo.cc: In function 'void cal(STU*)':
/in/foo.cc:42:10: error: expected unqualified-id before 'class'
   if (a->class > 80)a->scholarship += 4000;
          ^
/in/foo.cc:42:10: error: expected ')' before 'class'