// creat a public default Constructor (can constructor be private???)
public LinkedList()
{
// set default values
// assign null to Node head(both data and next are null???)
this.head = null;
// assign 0 to count
this.count = 0;
}
// creat a method named Add which has object data type output and has two argument int index and object o
public object Add(int index, object o)
{
// use if statement to control the user specified index won't smaller than 0
if ( index < 0)
{// if index < 0, throw a exception
throw new ArgumentOutOfRangeException("Index " + index);
}
// use if statement to control the user specified index won't bigger than count
if ( index > count)
{// if index > count, assign the heap of count to index
index = count;
}
// current point to the same heap that head point to
Node current = this.head;
// use if statement to deal with Empty is true or index == 0 is ture
if (this.Empty || index == 0)
{// when count is 0 and index is 0
//creat a Node object and invoke Node class constructor. assign o to data and assign head to next.Then head point to this Node object
// Node X = new Node();
// X.data = o;
// X.Next = head;
// head = X;
this.head = new Node(o, this.head);
}
// when count is not 0 and index == 0 is fasle
else
{// use for loop to process current = current.Next which measn change the heap that current point to until the loop stop
for (int i = 0; i < index -1; i++ )
{
current = current.Next;
}
// Node x = new Node(o, current.Next);
// x.data = o;
// x.Next = current.Next;
// current.Next = x;
current.Next = new Node(o, current.Next);
}
// count++
count++;
// return o
return o;
}
// this is a constructor with two argument which is declared above :data and next
public Node(object data, Node next)
{
//???
this.data = data;
this.next = next;
}
