调用struct默认析构函数？

Question

In C++, since you can have class-instances as members in structs, the compiler has an implicit destructor just like classes to clean them up. I can invoke a destructor of a class when I allocate an object into my own memory with the fixed-memory new-operator and need to clean it up, but what if I allocate a struct the same way? I know one workaround is to call the destructor of each class instance in the struct, just wondering if there was a way.

Answer 1

The same rules that apply to classes also apply to structs. The only difference between class and struct is the default access level, and no other.

Answer 2

There's no difference; class and struct are essentially identical:

class Bar { /* .. */ };

struct Foo
{
    Bar x;
};

char arena[HUGE];

Foo * p = ::new (arena) Foo;  // construct
p->~Foo();                    // destroy; calls the destructor for p->x as expected