如何创建继承的类对象的数组？

Question

I'm having a bit of trouble working on my current project. The project consists of taking lines of data from a file and creating an array of class objects that all inherit a base class.

So, this is what I understand so far:

class BaseClass {
    // create empty and non-empty constructor
}

class SubClass : public BaseClass {
    // create constructor specifically for this class 
}

int main() {
    BaseClass *array[size];
    array[index] = new SubClass();

    return 0;
}

Since the SubClass inherits the BaseClass, When I add a new object to the array it should be of type SubClass, correct?

When I debug the program and look at that object, it doesn't allow me to point to any of the SubClass methods/variables for manipulation which is what I need to be able to do.

Now when I was searching for answers I came across static casting, so I tried it to the extent of:

(static_cast<SubClass*>(array[index])->subclass_variable) = some_value

But that doesn't seem to work either, any help with this would be greatly appreciated.

Answer 1

One way to handle this is defining an interface (virtual methods) in the base class and implementation in SubClass :

class BaseClass {
    // create empty and non-empty constructor
    virtual void f() = 0;
}

class SubClass : public BaseClass {
    // create constructor specifically for this class 
    virtual void f() { std::cout << "I am your SubClass" << std::endl; }
}

Then you can call array[index]->f(); .

Another way is visiting / type switching on the class, another is NVI, but those are somewhat more advanced topics.