C++ a class using other class - c++

Question

I'm trying to define Node into NodeList class, And store it.
Whay I've tried is:
In Try() function, I defined a node like Node *node = malloc... This works fine. But if I use the node that I defined in class like node = malloc... this line gives runtime error. I don't understand what is the difference between these two.
Here are classes:
Node.hpp
#ifndef NODE_HPP
#define NODE_HPP
class Node{
public:
int data;
};
#endif
Node.cpp
#include <iostream>
#include "Node.hpp"
using namespace std;
NodeList.hpp
#ifndef NODELIST_HPP
#define NODELIST_HPP
#include "Node.hpp"
class NodeList{
public:
Node *node;
void Try();
};
#endif
NodeList.cpp
#include <iostream>
#include "NodeList.hpp"
#include "Node.hpp"
using namespace std;
void NodeList::Try(){
//This works (doesn't give error):
//Node *node = (Node*)malloc(sizeof(Node));
//But I use the node I defined in class here and this line gives runtime error:
node = (Node*)malloc(sizeof(Node));
}
Main.cpp
#include <iostream>
#include "NodeList.hpp"
using namespace std;
int main()
{
NodeList *node = NULL;
node->Try();
system("PAUSE");
return 0;
}

Answer 1

You code has many problems:
In Main.cpp you are dereferencing a NULL pointer: node->DosyaOku();, but node is NULL. This is an undefined behavior.
You have the same problem in NodeList.cpp
You are using a malloc in Node.cpp and you should probably want to use a new instead (read here), and you should think how to free/delete that pointer.
The Create in Node.cpp has a parameter that is overwritten immediately, that looks like an error.