C# How to use treeView to list the directories and subdirectories without showing the root directory?

Question

From

main folder
|_a
| |_b
| |_c
|_d
|_e

to

a
 |_b
 |_c
d
e

I want a treeview without the main folder. I foun

Answer 1

Try this, it looks real fast here. You can control whether all nodes are expanded or not.. You need to included the LINQ namspace (using System.Linq;)

// somewhere:
string yourRoot = "D:\\";
treeView1.Nodes.AddRange(getFolderNodes(yourRoot, true).ToArray());

private void treeView1_BeforeExpand(object sender, TreeViewCancelEventArgs e)
{
    TreeNode tn = e.Node.Nodes[0];
    if (tn.Text == "...")
    {
        e.Node.Nodes.AddRange(getFolderNodes(((DirectoryInfo)e.Node.Tag)
              .FullName, true).ToArray());
        if (tn.Text == "...") tn.Parent.Nodes.Remove(tn);
    }
}

List getFolderNodes(string dir, bool expanded)
{
    var dirs = Directory.GetDirectories(dir).ToArray();
    var nodes = new List();
    foreach (string d in dirs)
    {
        DirectoryInfo di = new DirectoryInfo(d);
        TreeNode tn = new TreeNode(di.Name);
        tn.Tag = di;
        int subCount = 0;
        try { subCount = Directory.GetDirectories(d).Count();  } 
        catch { /* ignore accessdenied */  }
        if (subCount > 0) tn.Nodes.Add("...");
        if (expanded) tn.Expand();   //  **
        nodes.Add(tn);
    }
    return nodes;
}

If you are sure you always want to see all levels expaded from the start you can use this function and delete the BeforeExpand code:

List getAllFolderNodes(string dir)
{
    var dirs = Directory.GetDirectories(dir).ToArray();
    var nodes = new List();
    foreach (string d in dirs)
    {
        DirectoryInfo di = new DirectoryInfo(d);
        TreeNode tn = new TreeNode(di.Name);
        tn.Tag = di;
        int subCount = 0;
        try { subCount = Directory.GetDirectories(d).Count(); } 
        catch { /* ignore accessdenied */  }
        if (subCount > 0)
        {
            var subNodes = getAllFolderNodes(di.FullName);
            tn.Nodes.AddRange(subNodes.ToArray());
        }
        nodes.Add(tn);
    }
    return nodes;
}

You call it as before:

string yourRoot = "D:\\";
Cursor.Current = Cursors.WaitCursor;
treeView1.Nodes.AddRange(getAllFolderNodes(yourRoot).ToArray());
Cursor.Current = Cursors.Default;