vb.net - Linked Structures in Visual Basic; is it possible to implement a double reference? -

when 1 traversing linked structure intent of acting upon structure (i.e.: inserting node simple linked list trivial example,) 1 obtains best algorithm pushing double pointer through structure; if single reference used, 1 must write 1 or more special cases null roots and/or tail insertions.

node_type **dp = &root;  while(*dp && /insertion point not reached/) dp=&(*dp)->next; 

when fall out of loop, *dp point of insertion list; i'm holding reference object's link. reference might root, null object @ end of structure, or other node. structure becomes more complex, need double-reference becomes more pronounced need special cases tends grow exponentially.

how 1 implement double-reference in visual basic?

note: linked list bit serves example... know: there lots of ways around simple issue.

please excuse c#, vb.net rather rusty. way safely double references in c#/vb.net using ref parameter method.

using system;  namespace test {     class program     {         private static void main(string[] args)         {             // create example root node. example still works when root             // null.             node root = new node() { next = new node() };              // setup node contains pointer root. variable             // not destroyed iteration , rp.next root             // after iteration, if root started null.             node rp = new node() { next = root };              // initialize iterator root pointer.             node dp = rp;              // define new node inserted example.             node nn1 = new node();             node nn2 = new node();              // iterate calling dowork until null reference returned.             // note reference dp.next passed method.             // allows method change dp.next points to. node             // insert given method. change             // second parameter action works on desired node.             while(null != (dp = dowork(ref dp.next, nn1))) { }             dp = rp;             while(null != (dp = dowork(ref dp.next, nn2))) { }              // force root assigned. if root did not start null             // line unnecessary.             root = rp.next;         }          private static node dowork(ref node node, node nn)         {             // logic determine if insertion point not reached.             // example new node inserted before tail.             bool logic = null != node && null != node.next;              // check node , logic. return node continue iterating.             if(null != node && logic)             {                 return node;             }              // insertion logic here. example new node inserted             // linked list.             nn.next = node;             node = nn;              // return null signify iteration has completed.             return null;         }     }      [system.diagnostics.debuggerdisplay("{id} - {next}")]     class node     {         private static int sid;          public int id;         public node next;          public node()         {             id = ++sid;         }     } }