Argument for IEnumerator on TreeNode

Question

what is the valid argument for IEnumerator on TreeNode?

i got the error on this line:

IEnumerator ie = tn.Nodes.GetEnumerator();

in this method:

private void parseNode(TreeNode tn)
    {
        IEnumerator ie = tn.Nodes.GetEnumerator();

        string parentnode = "";

        parentnode = tn.Text;

        while (ie.MoveNext())
        {
            TreeNode ctn = (TreeNode)ie.Current;

            if (ctn.GetNodeCount(true) == 0)
            {
                _nodeToString += ctn.Text;
            }
            else
            {
                _nodeToString += "<" + ctn.Text + ">";
            }
            if (ctn.GetNodeCount(true) > 0)
            {
                parseNode(ctn);
            }
        }

        _nodeToString += "</" + parentnode + ">";
        _nodeToString += "\n";
    }

orthoganol to the question, but why not use the `foreach (TreeNode node in tn.Nodes)`? — Sam Holder, Jun 05 '11 at 15:00
and also what error do you get? That would be helpful to know... — Sam Holder, Jun 05 '11 at 15:01
are you building xml via string concatenation? that is not a great idea... `XmlWriter` would be ideal here... — Marc Gravell, Jun 05 '11 at 15:04
yep.. im building for xml.. :) the error is Error 1 Using the generic type 'System.Collections.Generic.IEnumerator' requires '1' type arguments — Vincent Dagpin, Jun 05 '11 at 15:09
just want also to convert the nodes to string in xml format.. :) — Vincent Dagpin, Jun 05 '11 at 15:10

Marc Gravell · Accepted Answer · 2011-06-05T15:23:11.650

(from comments)

Using the generic type 'System.Collections.Generic.IEnumerator' requires '1' type arguments

That means you have

using System.Collections.Generic;

and not

using System.Collections;

switch to the latter and it will work. IEnumerable / IEnumerator are the non-generic API.

Or better: use foreach - it is simpler, safer and more correct (you didn't remember to check for IDisposable, for example).

Additional notes:

concatenating strings in a loop is very bad - it causes telescopic string allocations (i.e. lots of intermediate strings); something like StringBuilder is preferred by a long margin
building xml by hand is not ideal - you need to encode etc; XmlWriter would be ideal

so IMO: use an XmlWriter that writes to a StringBuilder, using foreach

Untested, but something like:

    private string parseNode(TreeNode tn)
    {
        var sb = new StringBuilder();
        using (var writer = XmlWriter.Create(sb))
        {
            writer.WriteStartElement("xml");
            parseNode(tn, writer);
            writer.WriteEndElement();
        }
        return sb.ToString();
    }
    private void parseNode(TreeNode tn, XmlWriter writer)
    {
        if (tn.Nodes.Count > 0)
        {
            writer.WriteStartElement(tn.Text);
            foreach (TreeNode child in tn.Nodes)
            {
                parseNode(child, writer);
            }
            writer.WriteEndElement();
        }
        else
        {
            writer.WriteString(tn.Text);
        }
    }

Or use System.Collections.IEnumerator instead of "IEnumerator". — Larry Osterman, Jun 05 '11 at 15:18
anyway, there's an argumentexception at writer.WriteStartElement(tn.Text); it says Invalid name character in 'f:\'. The ':' character, hexadecimal value 0x3A, cannot be included in a name. — Vincent Dagpin, Jun 05 '11 at 15:34
@vrynxzent, Unless you can be sure all nodes use a valid XML name as text, you should consider writing the text as attributes or text instead of node names. `...` or `f:\...`. — Markus Jarderot, Jun 05 '11 at 15:53

Argument for IEnumerator on TreeNode

1 Answers1