What is the preferred way of allocating C++ class member data?

Question

Let's say I have a class that allocates some arbitrary member data. There are two common ways that I have seen used (I know that there are others):

class A
{
    public:
        A();
        ~A();

        //Accessors...
    private:
        B *mB;
}

A::A()
{
    mB = new B();
}

A::~A()
{
    delete B;
}

Versus...

class A
{
    public:
        //Accessors...
    private:
        B mB;
}

Assume that A itself will be allocated on the heap by consumer code.

In the general case, which method is preferred? I realize that specific situations really encourage one way or the other, but in absence of those demands, is one way preferred? What are the tradeoffs?

Answer 1

The second is the preferred route. Do not use new / delete unless you specifically need a variable to be on the heap or have a lifetime longer than it's container. C++ value types are easier to manage and have less error cases to worry about IMHO