Position of an item and 'Cannot implicitly convert type to string error'
<p>I am working with lists. I am now experimenting with determining the positions of items inside list: <code>first</code>, <code>next</code> and <code>last</code>. I have been able to determine the first and last position of items in my list through function <code>getPostion</code> and displaying the item name through a Label. Three buttons in my form: ShowFirstItem ShowNextItem and ShowLastItem show the corresponding item in a label. I am having problems for displaying the next item. I have special method for <code>next</code> called <code>GetNextTree</code>. When I am calling this method from inside <code>ShowNextItem</code> click I get this error: <code>Cannot implicitly convert type 'TreeFarm.Form1.fruit_trees' to 'string'.</code> How can avoid this error and display the item currently pointed to?</p>

<pre><code>namespace TreeFarm {
     public partial class Form1: Form {
         public Form1() {
             InitializeComponent();
         }

         public class ListForTrees {


             public fruit_trees GetNextTree() {
                 //save currently pointed tree
                 fruit_trees tree = this.current_tree;
                 if (tree != null) {
                     //move current_tree to the next tree, to be returned next time
                     current_tree = current_tree.next_tree;
                     //return saved tree object
                 }
                 return tree;
             }

         }
         private void ShowNextItem_Click(object sender, EventArgs e) {
             //Show Next Item
             labelSpecificTree.Text = mainlist.GetNextTree();
         }

     }
</code></pre>
