How to output dynamic arrays values form container array in c++?

Question

I will try to explain my situation a first. I have a class with structure inside of it and an array of this container calss

class A
{
    struct B
    {
        int I;
        B *next;
    };

    B *objOfB; //Array of structures
    B *lastB;  //Pointer to last objOfB element

public:
    //Method for adding values to objOfB
    void addB(int i)
    {
        B *temp = new B;
        temp->I = i;
        temp->next = NULL;
        if(ing == NULL)
        {
            last = temp;
            objOfB = temp;
        }
        else
        {
            last->next = temp;
            last = temp;
        }
    }
};

Object's array is used in some functions file

A * objA = A[100];

What I can not figure out is how to hand single value of objOfB. There is a simple example which will go from start to end of objOfB.

for (B *temp = objOfB; temp != NULL; temp = temp->next) {
  cout << temp->I << endl;
}

I would like to execute this loop in functions file but I can not think of method which would not return all objOfB (it is used in the first part of the loop B *temp = objOfB;). Here are the methods I have created to execute this loop:

B listOfBs() { return *objOfB;  }
B toNextB() { return *objOfB->next; }
bool noLastB(){ return objOfB->next != NULL; }

And how it works it may be used in the loop:

for (B *temp = listOfBs(); noLastB(); temp = toNextB()) {
  cout << temp->I << endl;
}

However I understand that all 3 methods are not suitable for this loop. So I need some method to return value and another one to tell that the next value should be read... Hope not it is clearer what I am trying to achieve.

How to pass container class dynamic arrays of structures value using a method?

Answer 1

From what I understand, you have the class A (that represents a wrapper of singly-linked list) and this simple struct B nested in it :

struct B
{
    int I;
    B *next;
};

and you want the class A to also provide an interface, that would provide the simpler way of iterating through this list.

At first, this data member is very confusing:

B *objOfB; //Array of structures

since you are treating it as a pointer to the first element. Good start would be to rename it to: B *head; So now each instance of B can point to the next element and you have the pointer to the head, last element is the element with next equal to NULL, you don't need B *lastB;.

Then you will realize that methods you tried to provide don't make much sense:

B listOfBs() { return *head;  }
B toNextB() { return *head->next; }
bool noLastB(){ return head->next != NULL; }

there is no reason why these methods should return by value and since the definition of struct B will have to be visible to the caller anyway. For the sake of KISS principle, just make head the public data member of A and rename A to more meaningful name, for example MyList. Then let the caller do this:

MyList list;
...
for (B* b = list.head; b != NULL; b = b->next) {
    ...
}