MJ1986 MJ1986 -4 years ago 44
C++ Question

C++ Child class can't access other child class vector

At a loss here hope someone can help..

I have the following class structure.

A base class Room with two child classes Kitchen, and livingRoom.

I have a vector in my base class

Room::Room()
{
up = nullptr;
down = nullptr;
left = nullptr;
right = nullptr;

pocket = new vector<string>;

}


Defined as:

void Room::addPocket(string item)
{
char emptyPocket;

if (pocket->size()==1)
{
emptyPocket = 'N';
}

if(pocket->size()<1)
{
pocket->push_back(item);
cout << "Item added to pocket" << endl;
}
else
{
cout <<"Your pocket is full" << endl;
cout <<"Would you like to empty your pocket? 'Y' or 'N'" << endl;
cin >> emptyPocket;
if(emptyPocket == 'Y' || emptyPocket == 'y')
{
pocket->clear();
cout <<"You have emptied your pocket." << endl;
}
}
}


And my program function as follows. I have a another class Game, where the following happens. I go into the child class Kitchen and add to the vector. Go back into Game class. I move into the livingRoom class and when I access the vector, it's empty? What am I missing here.

Answer Source

Base class data is not shared between different instances of child classes. Each child class is, and effectively contains, a distinct instance of the base class.

So Kitchen has a pocket and livingRoom has another pocket. What is added to Kitchen's pocket is not added to LivingRoom's pocket.

Instead, you should look into making another class to represent the entity that is moving between the rooms and have this entity class contain pocket. No matter what room an entity is in, it always has the same pocket.

Also shy away from dynamically allocating std::vectors. They were designed to take away all of the responsibilities of managing dynamic allocations, so dynamically allocating a vector merely puts some of the those management responsibilities back into play for no benefit.

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