both asterisk and ampersand in a parameter c++

Question

I am reading a book about Binary Search Tree and something weird came up.

class BST
{
public:
   void insert(const Comparable & item)

private:
   Binary         


        

Answer 1

It's reference to pointer, you can change pointer in this function and it will changed outside. Simple example http://liveworkspace.org/code/1EfD0Q$8

Answer 2

In your expression BinaryNode * & t)

            BinaryNode*                & t
           -------------              -----
            BinaryNode pointer        t is reference variable  

so t is reference to pointer of BinaryNode class.

Pointer of the address of t?

You are confused ampersand & operator in c++. that give address of an variable. but syntax is different.

ampersand & in front of some of variable like below:

BinaryNode b;
BinaryNode* ptr = &b;

But following way is for reference variable (its simple not pointer):

BinaryNode b;
BinaryNode & t  = b; 

and your is like below:

BinaryNode b;
BinaryNode* ptr = &b;
BinaryNode* &t  = ptr;