Question

I have a reset() function that goes through a bunch of data and resets it. One of these is a pointer to a custom class, let’s say Apple *a;

The Apple class has a vector<Seed *> object, and a method resetSeeds() to go through and reset them all.

If reset() is called before a is allocated, I don’t want resetSeeds to iterate over its Seed objects, since these aren’t allocated yet. How do I do this?

Answer 1

Set a to NULL to begin with. Then, in reset(), only call a->resetSeeds() if a is not NULL:

class Foo
{
private:
    Apple* a;

public:
    Foo() : a(NULL) { }

    void reset()
    {
        if (a != NULL) {
            a->resetSeeds();
        }
    }
};

If you’re using C++11, switch out NULL in favour of nullptr.