variables scoping when inheriting

Question

I have two classes in C++, where one inherits from the other:

class A {
public: 
    virtual void Initialize(){
        m_MyString = "Default value";
    }

protected: 
     string m_MyString;
}

class B : public A {
public: 
    void Initialize(){ 
       A::Initialize(); 
       m_MyString = "New Value";
    }
}

Is there a difference between the above class B and this one?

class B : public A {
public: 
    void Initialize(){ 
       A::Initialize(); 
       A::m_MyString = "New Value";
    }
}

It seem using the scoping operator will result in a the string having garbage, correct? I'm thinking when it overrides, the A::m_MyString is different than B::m_MyString. Does this even make sense?

I'm seeing the variable get set in A, then when we return to B, have garbage. This has to do with "hidden" vs. overridden?

Answer 1

Your code is not valid in many ways. It should look like:

class A { // << errors were here
public: 
    virtual void Initialize(){
        m_MyString = "Default value";
    }

protected: 
     string m_MyString;
}; // << lost ;

class B : public A // << errors were here
{
public: 
    virtual void Initialize(){  // << virtual
       A::Initialize(); // has no effect in the end

       A::m_MyString = "New Value"; // same as `m_MyString = "New Value";`
    }
}; // << lost ;

In the code above there is no difference with m_MyString. Post your actual code with error.

If your code looks like:

class B : public A
{
public: 
    virtual void Initialize(){
       // here is a difference
       A::m_MyString = "New Value"; 
       m_MyString = "New Value";
    }
protected: 
     string m_MyString; // !!! overridden
};

Then there is a difference because B has two instances of m_MyString: A::m_MyString and B::m_MyString.