Strange behaviour from XmlReader

Hello,

I've been using the XmlReader class to read xml files.
Lately it has had some strange quirks. It seems to ignore elements when
there is no whitespace between them.

ex
<main><textline><textelement>A</textelement>
<textelement>B</textelement<textelement>C</textelement></textline></main>
(really on one line)

works fine, but with

<main><textline><textelement>A</textelement><textelement>B</textelement><textelement>C</textelement></textline></main>

it skips element B.

and with
<main><textline><textelement>A</textelement>
<textelement>B</textelement><textelement>C</textelement></textline></main>

it skips element C

A short program to demonstrate the problem:

using System;
using System.Xml;
using System.IO;

namespace XmlTest
{
class TestXml
{
public static void Main()
{
string xml =
"<main><textline><textelement>A</textelement><textelement>B</textelement><textelement>C</textelement></textline></main>";
StringReader strReader = new StringReader(xml);
XmlReader reader = XmlReader.Create(strReader);
reader.MoveToContent();
int i = 0;
while (!(reader.NodeType == XmlNodeType.EndElement &&
reader.Name.Equals("textline")))
{
reader.Read();
if (reader.NodeType == XmlNodeType.Element &&
reader.Name.Equals("textelement"))
{
string text = reader.ReadElementString();
Console.WriteLine("{0} {1}", i, text);
i++;
}
}
Console.ReadLine();
}
}
}

This now prints
0 A
1 C

It should have printed
0 A
1 B
2 C

Does anyone have any idea what I might be doing wrong?
I had always thought that whitespace was irrelevant in xml.

Jan Obrestad

Martin Honnen

Guest

n/a Posts

June 27th, 2008
07:20 PM
#2

Re: Strange behaviour from XmlReader

Jan Obrestad wrote:

Quote:

string xml =
"<main><textline><textelement>A</textelement><textelement>B</textelement><textelement>C</textelement></textline></main>";
>
StringReader strReader = new StringReader(xml);
XmlReader reader = XmlReader.Create(strReader);
reader.MoveToContent();

Now the reader is positioned on the 'main' start tag.

Quote:

int i = 0;
while (!(reader.NodeType == XmlNodeType.EndElement &&
reader.Name.Equals("textline")))
{
reader.Read();
if (reader.NodeType == XmlNodeType.Element &&
reader.Name.Equals("textelement"))
{
string text = reader.ReadElementString();
Console.WriteLine("{0} {1}", i, text);
i++;
}
}

For the first run of the loop:
reader.Read() moves reader to the 'textline' start tag.
On the second run of the loop:
reader.Read() moves reader to the 'textelement' start tag.
reader.ReadElementString() moves reader past the 'textelement' end
tag, meaning it is now positioned on the second 'textelement' start tag.
Output: i as 0, text as 'A'.
i set to 1
On the third run of the loop:
reader.Read() moves reader to the text node with contents 'B'.
So there you have the problem, your combination of
Read/ReadElementString and your conditions fail to find the second
'textelement' start tag.

As a solution you might want to use ReadString() instead of
ReadElementString().

--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/