c++ arrays tips - Pointers, arrays, and problems

[ben2ong2]

PROBLEM: C++ has a very large hole concerning type safety regarding pointers
and arrays.


RESPONSE: Taken from class notes on Adv C++ by Desmond Dsouza

class A {
public:
   int av;
};

class B : public A {
public:
   int bv;
};

void f (A* x)
{
   x[1].av = 0;
}

main ()
{
   B y [100];
   y

• .bv = 1;   
  
     f (y);
  
     // One of the B in the array has just been stomped on.
     // This assertion will fail.
  
     assert (y
• .bv == 1);
  }
  
  
  Never write methods that accept (manipulate) arrays of objects of types
  that may be subclasses. Someday they will fail!