Question

I’m having trouble with C++ calling elements of an array of type class.
Here is a sample of my code;

//village.h
class village
{
    public:
        class Human
        {
            public:
                void setGender(std::string g);
                std::string getGender();
            private:
                std::string gender;
        };

        class World
        {
            public:
                void join(Human c, int i);
            private:
                Human humanArray[20];
        };

//village.cpp
void village::World::join(Human c, int i)
{
    humanArray[i] = c;
    cout << humanArray[i].gender << endl;
    cout << c.getGender() << endl;
}

//main.cpp

village::Human h;
village::World world

h.setGender("Male");
world.join(c, 1);

The problem I’m having is, I’m getting error in the line;

cout << humanArray[i].gender << endl;

saying

‘gender’ is private.

However, didn’t I declare the array of type Human? And I’m not getting error when adding so I assume this works ok. But when I try and call an element, I’m getting error. I can’t change the variables from private to public.

Answer 1

Change it to

cout << humanArray[i].getGender() << endl;

Technical background on why this works:

The member variable gender is declared private in the Human class, thus other classes (and instances of them) cannot access it (without special permission). The member functions Human::getGender() and Human::setGender() are declared public, so they can be accessed on instances (objects) of class Human.

Because a member function can access private members (variables and functions) of the class it belongs to, Human::getGender() (also true for Human::setGender()) can access the private gender member variable of class Human.

The function join() is a member of class World, which is distinct from class Human, thus it has access to public members only (i.e. has access to Human::getGender(), but not to Human::gender)

Accessing the elements of the array has nothing to do with the above. All elements of an array can be accessed by code that has visibility/access to the array (think of the elements as if they were public within the array, with no way to set them private)