linked list: why does 'root-> next' change when...

[rmurv]

Got this code from tutorial

#include <iostream>
using namespace std;
struct node {
  int x;
  node *next;
};

int main()
{
  node *root;       // This won't change, or we would lose the list in memory
  node *conductor;  // This will point to each node as it traverses the list

  root = new node;  // Sets it to actually point to something
  root->next = 0;   //  Otherwise it would not work well
  root->x = 12;
  conductor = root; // The conductor points to the first node
  if ( conductor != 0 ) {
    while ( conductor->next != 0)
      conductor = conductor->next;
  }
 cout << "Before    " << root->next << endl;
  conductor->next = new node;  // Creates a node at the end of the list

//Why does 'root -> next' change  here?
 cout << "After    " << root->next;
  conductor = conductor->next; // Points to that node
  conductor->next = 0;         // Prevents it from going any further
  conductor->x = 42;
cin.get();
}

[hk_mp5kpdw]

root and conductor are pointing to the same thing before the second node gets created. When you add a new node to conductor->next, you are also effectively updating root->next.

[Elysia]

Code does not free root. Consequently, it's bad code.

[robwhit]

conductor->next = 0; //conductor is 0.