Correct way of initializing a struct in a class constructor

Question

So I want to add a struct from a c header file as a class member to a c++ class. But I get a compiler error for the cpp file: bar was not declared inn thi

Answer 1

Let us consider an example. Consider a Linked List in which each node is represented by:

struct ListNode {
     int val;
     ListNode *next;
     ListNode(int x){
        val = x;
        next = NULL;
     }
};

To initialize a node with value 5 and next pointer pointing to NULL you can write the code snippet as:

ListNode node = new ListNode();
node.val = 5;
node.next = NULL;

or

ListNode node = new ListNode(5);

Another fancy declaration can be made as

struct ListNode {
     int val;
     ListNode *next;
     ListNode(int x) : val(x), next(NULL) {}
};

Here ListNode(int x): val(x), next(NULL) is a constructor which initializes the value of the struct ListNode.

Hope this make things more clear and easy. :)