Is it safe to cast between two unrelated types if their structures are similar?

This is piece of code from our team's small project (acdemic)

class B{
public:
 DWORD GetLen(){return i;}
 DWORD i ;
};
class A
{
public:
 DWORD GetLen(){return j;}
public:
 int j ;

};

 B b;
 b.i = 2;
 A * pA = (A *)&b;
 int j = pA->GetLen();

"j" will be 2. Is this code safe? Or, what should I modify it? By using rein开发者_开发百科terpret_cast or static_cast? or other thoughts?

Is this code safe?

No.

What should I do to correct it?

Remove the cast and only call member functions of A on instances of A.

As for what you should do instead, well, that depends entirely on what you're actually trying to do.

This code is not safe. In C++ use casting operators, e.g.: dynamic_cast, reinterpret_cast etc.

In this case casting is not allowed, and you're lying to the compiler.

It only works because the classes are essentially identical.