Question

Attempting to write a constructor for LinkedList to be initialised with an array of integers.

The program would call linked(array); which will add all the values within the array in to a linkedlist.

LinkedList::LinkedList(int array[])
{
    headPtr->setData(array[0]); //setData method stores the integer at position 0 inside headPtr

    Node *currentPtr = headPtr;

    for (int i = 0; i < array.length(); ++i)    //for loop to add the integers to the next node
    {
        currentPtr->setNext(new Node(array[i])); //creates a new node with the integer value of array position i
    }
}

the trouble is the array.length (coming from Java) and I don’t think the array length can be obtained this way?

Answer 1

Like others have said, it is not only important but vital that you get a good introductory C++ book and read it from front to back, simultaneously trying to forget what you know about Java while in C++ mode. They are not remotely similar.

Now to your problem, it can be solved by using std::vector and using its size method:

// put this with the other includes for your file
#include <vector>

LinkedList::LinkedList(const std::vector<int>& array)
{
    headPtr->setData(array[0]); //setData method stores the integer at position 0 inside headPtr

    Node *currentPtr = headPtr;

    for (int i = 0; i < array.size(); ++i)    //for loop to add the integers to the next node
    {
        currentPtr->setNext(new Node(array[i])); //creates a new node with the integer value of array position i
    }
}

If you don’t want to use vector, you have to pass in the size of the array to the function:

LinkedList::LinkedList(int array[], int arrlen)
{
    headPtr->setData(array[0]); //setData method stores the integer at position 0 inside headPtr

    Node *currentPtr = headPtr;

    for (int i = 0; i < arrlen; ++i)    //for loop to add the integers to the next node
    {
        currentPtr->setNext(new Node(array[i])); //creates a new node with the integer value of array position i
    }
}

But it is recommended to use the vector version.