Why the string is always empty?

I try to use LINQ to read XML file. However, the string which store the value of selected attribute is always empty.

Here is the code:

        string output = "";
        XDocument loaded = XDocument.Load(@"d:\input.xml");

        var ta = from tmp in loaded.Descendants("NewDataSet.Table")
                select tmp.Element("E1");

    开发者_C百科    foreach (string ss in ta)
        {
            ouput += ss;

        }

The output string is always empty. But the ss string has correct value.

What is the problem?

I've no idea how to add xml file with style. So i have to update the xml file as image. :(

Now that you have shown your XML, here's how to fix your code:

var ta = from tmp in loaded.Descendants("Table")
         select tmp.Element("E1");

You do not use . in XML as you do in C# to navigate the XML tree. You could also navigate a XML tree using XPath:

var ta = from tmp in loaded.XPathSelectElements("NewDataSet/Table/E1")
         select tmp;

Also I would recommend you to use a StringBuilder instead of string concatenations for this output variable:

var ta = from tmp in loaded.Descendants("Table")
         select tmp.Element("E1");

var builder = new StringBuilder();
foreach (string ss in ta)
{
    builder.Append(ss);
}
string output = builder.ToString();

var ta = from tmp in loaded.Descendants("Table")
select tmp.Element("E1");