Parse XML string using C#

A possible solution would be to use LINQ2XML:

// retrieve a single element by tag name
private XElement getElement(XDocument xmlDocument, string elementName)
{
    var element = xmlDocument.Descendants("items").Elements().Where (x => x.Name == elementName).FirstOrDefault();
    return element != null ? element : null;
}

// retrieve attribute by name
private string attributeValue(XElement item, string attributeName)
{
    var attribute = item.Attribute(attributeName);
    return attribute != null ? attribute.Value : string.Empty;
}

The two functions can be used like this:

// input for the example
var input = @"<items>
<item1 value=""value1"" />
<item2 value=""value2"" />
<item3 value=""value3"" />
<itme4 value=""value4"" />
<item5 value=""value5"" />
<item6 value=""value6"" />
</items>";

var xml = XDocument.Parse(input);
var element = getElement(xml, "item2");
if (element != null)
{
    Console.WriteLine(attributeValue(element, "value"));
}

The output is:

value2

For a repetative tasks like this it is often advantageous to implement the methods as extensions:

public static class ProjectExtensions
{
    // retrieve a single element by tag name
    public static XElement GetElementByName(this XDocument xmlDocument, string parentElementName, string elementName)
    {
        var element = xmlDocument.Descendants(parentElementName).Elements().Where (x => x.Name == elementName).FirstOrDefault();
        return element != null ? element : null;
    }

    // retrieve attribute by name
    public static string GetAttributeValueByName(this XElement item, string attributeName)
    {
        var attribute = item.Attribute(attributeName);
        return attribute != null ? attribute.Value : string.Empty;
    }
}

The usage is IMO much more easier and cleaner:

var xml = XDocument.Parse(input);
var element = xml.GetElementByName("items", "item2");
if (element != null)
{
    Console.WriteLine(element.GetAttributeValueByName("value"));
}

You can of course (as already suggested) use XPath directly.

leave all your code the same but change this :

string item1 = xmlDoc.GetElementsByTagName("item1")[0].Attributes[0].Value;

do the same for other items , and you will get the value.

Assuming you want the value attribute of each of your item elements, you could use Xpath:

        string xmlString = "<items><item1 value=\"value1\" /><item2 value=\"value2\" /><item3 value=\"value3\" /><item4 value=\"value4\" /><item5 value=\"value5\" /><item6 value=\"value6\" /></items>";

        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.LoadXml(xmlString);

        string item1 = xmlDoc.SelectSingleNode("items/item1/@value").InnerText;
        string item2 = xmlDoc.SelectSingleNode("items/item2/@value").InnerText;
        string item3 = xmlDoc.SelectSingleNode("items/item3/@value").InnerText;
        string item4 = xmlDoc.SelectSingleNode("items/item4/@value").InnerText;
        string item5 = xmlDoc.SelectSingleNode("items/item5/@value").InnerText;
        string item6 = xmlDoc.SelectSingleNode("items/item6/@value").InnerText;

You missunderstand the term 'Attribute', you are trying to catch "item1" and it is actually a Node.

Use this:

string item1 = xmlDoc.SelectSingleNode("//items/item1").Attributes["value"].value;

There are other options, but this will give you the values you are looking for.

Cheers...

this will get you all those attributes values:

1)Load xml with XDocument.Load() if from a string XDocument.Parse() then do this:

IEnumerable<string> result = from node in xmlDoc.Root.Descendants()
                             select node.Attribute("value").Value;