Array of Pointers to Structs

Every once in a while, I mean year, I need to create an Array of Pointers to Structs (at runtime - user defined size) and i can NEVER remember how to do it and my reference book example doesnt seem to help me too much. So, I made a test prog to do so yet it blows up on me at the end. What am i missing... this time?

Code:

---

#include <iostream>
using namespace std;

struct node
{
        int n;
        node * ptrnode;
        node(){n = 0; ptrnode = NULL;}
};

class Obj
{
public:
        Obj(){size = 0; root = NULL;}
        Obj(int i)
        {
                size = i;
                root->ptrnode = new node[i];
        }
//private:
        int size;
        node * root;
};


int main()
{
        int i;
        cout<<"create number: ";
        cin>> i;
        Obj test(i);
        cout << "Size is " << test.size;
        return 0;
}

---

In the constructor Obj (int i), root is not initialised to point at anything valid, but root->ptrnode is assigned to. That causes undefined behaviour.

One day you'll learn about std::vector.

Until that day comes, you should remember that in your constructor of Obj, you want to set root to be a pointer to an array, not root->ptrnode. (Unless you're trying to set a linked list, but you wouldn't do that in advance, so that can't be what you mean.)

Thnxs. I gotta engrave this into my head somehow.

EDIT: heh i just read about the mention of "vector" in my book. It does sounds like it will make things a lot easier, but i dont wanna keep on forgetting the basics which i tend to do quite often :/