Develop Reference

how to change xml string value on fly

I have an xml response string and I want to change a value inside and log it.
<xml>
<ns2:abcd>
<password>sample</password>
</ns2:abcd>
I want to change the password value into encrypted version.
I am have tried using XmlDocument.SelectSingleNode but was thinking is there any better way than this?

Btw you need ns2 namespace to be declared, otherwise your xml will not be valid. After adding namespace definition, you can parse and modify your xml with Linq to Xml:
XDocument xdoc = XDocument.Parse(xml);
var passwordElement = xdoc.XPathSelectElement("//password");
passwordElement.Value = Encrypt((string)passwordElement);
xdoc.Save(path_to_xml);

No - there is no better way than using proper XML classes.
XmlDocument or XDocument would be perfectly fine for this task. If you XML is very large you may want to look into streaming with XmlReader (unlikely necessary in your case).

You might also consider looking into xsd.exe. With xsd.exe, you can deserialize your xml into a type-safe object model. From there, it's easy to manipulate the data.

What is the easiest way of handling xml files with C#?

I'm developing a windows app using C#. I chose xml for data storage.
It is required to read xml file, make small changes, and then write it back to hard disk.
Now, what is the easiest way of doing this?

XLinq is much comfortable than the ordinary Xml, because is much more object oriented, supports linq, has lots of implicit casts and serializes to the standard ISO format.

The best way is to use XML Serialization where it loads the XML into a class (with various classes representing all the elements/attributes). You can then change the values in code and then serialize back to XML.
To create the classes, the best thing to do is to use xsd.exe which will generate the c# classes for you from an existing XML document.

I think the easiest way of doing it - it is using XmlDocument class:
var doc = new XmlDocument();
doc.Load("filename or stream or streamwriter or XmlReader");
//do something
doc.Save("filename or stream or streamwriter or XmlWriter");

I think I found the easiest way, check out this Project in Codeproject. It is easy to use as XML elements are accessed similarly to array elements using name strings as indexes.
Code sample to write bool property to XML:
Xmlconfig xcfg = new Xmlconfig("config.xml", true);
xcfg.Settings[this.Name]["AddDateStamp"]["bool"].boolValue = checkBoxAddStamp.Checked;
xcfg.Save("config.xml");
Sample to read the property:
Xmlconfig xcfg = new Xmlconfig("config.xml", true);
checkBoxAddStamp.Checked = xcfg.Settings[this.Name]["AddDateStamp"]["bool"].boolValue;
To write string use .Value, for int .intValue.

You can use LINQ to read XML Files as described here...
LINQ to read XML

Check out linq to XML

C# XML conversion

I have a string containing fully formatted XML data, created using a Perl script.
I now want to convert this string into an actual XML file in C#. Is there anyway to do this?
Thanks,

You can load a string into an in-memory representation, for example, using the LINQ to SQL XDocument type. Loading string can be done using Parse method and saving the document to a file is done using the Save method:
open System.Xml.Linq;
XDocument doc = XDocument.Parse(xmlContent);
doc.Save(fileName);
The question is why would you do that, if you already have correctly formatted XML document?
A good reasons that I can think of are:
To verify that the content is really valid XML
To generate XML with nice indentation and line breaks
If that's not what you need, then you should just write the data to a file (as others suggest).

Could be as simple as
File.WriteAllText(#"C:\Test.xml", "your-xml-string");
or
File.WriteAllText(#"C:\Test.xml", "your-xml-string", Encoding.UTF8);

XmlDocument doc = new XmlDocument();
doc.Load(... your string ...);
doc.Save(... your destination path...);
see also
http://msdn.microsoft.com/fr-fr/library/d5awd922%28v=VS.80%29.aspx

How do I work with an XML tag within a string?

I'm working in Microsoft Visual C# 2008 Express.
Let's say I have a string and the contents of the string is: "This is my <myTag myTagAttrib="colorize">awesome</myTag> string."
I'm telling myself that I want to do something to the word "awesome" - possibly call a function that does something called "colorize".
What is the best way in C# to go about detecting that this tag exists and getting that attribute? I've worked a little with XElements and such in C#, but mostly to do with reading in and out XML files.
Thanks!
-Adeena

Another solution:
var myString = "This is my <myTag myTagAttrib='colorize'>awesome</myTag> string.";
try
{
var document = XDocument.Parse("<root>" + myString + "</root>");
var matches = ((System.Collections.IEnumerable)document.XPathEvaluate("myTag|myTag2")).Cast<XElement>();
foreach (var element in matches)
{
switch (element.Name.ToString())
{
case "myTag":
//do something with myTag like lookup attribute values and call other methods
break;
case "myTag2":
//do something else with myTag2
break;
}
}
}
catch (Exception e)
{
//string was not not well formed xml
}
I also took into account your comment to Dabblernl where you want parse multiple attributes on multiple elements.

You can extract the XML with a regular expression, load the extracted xml string in a XElement and go from there:
string text=#"This is my<myTag myTagAttrib='colorize'>awesome</myTag> text.";
Match match=Regex.Match(text,#"(<MyTag.*</MyTag>)");
string xml=match.Captures[0].Value;
XElement element=XElement.Parse(xml);
XAttribute attribute=element.Attribute("myTagAttrib");
if(attribute.Value=="colorize") DoSomethingWith(element.Value);// Value=awesome
This code will throw an exception if no MyTag element was found, but that can be remedied by inserting a line of:
if(match.Captures.Count!=0)
{...}
It gets even more interesting if the string could hold more than just the MyTag Tag...

I'm a little confused about your example, because you switch between the string (text content), tags, and attributes. But I think what you want is XPath.
So if your XML stream looks like this:
<adeena/><parent><child x="this is my awesome string">This is another awesome string<child/><adeena/>
You'd use an XPath expression that looks like this to find the attribute:
//child/#x
and one like this to find the text value under the child tag:
//child
I'm a Java developer, so I don't know what XML libraries you'd use to do this. But you'll need a DOM parser to create a W3C Document class instance for you by reading in the XML file and then using XPath to pluck out the values.
There's a good XPath tutorial from the W3C schools if you need it.
UPDATE:
If you're saying that you already have an XML stream as String, then the answer is to not read it from a file but from the String itself. Java has abstractions called InputStream and Reader that handle streams of bytes and chars, respectively. The source can be a file, a string, etc. Check your C# DOM API to see if it has something similar. You'll pass the string to a parser that will give back a DOM object that you can manipulate.

Since the input is not well-formed XML you won't be able to parse it with any of the built in XML libraries. You'd need a regular expression to extract the well-formed piece. You could probably use one of the more forgiving HTML parsers like HtmlAgilityPack on CodePlex.

This is my solution to match any type of xml using Regex:
C# Better way to detect XML?

The XmlTextReader can parse XML fragments with a special constructor which may help in this situation, but I'm not positive about that.
There's an in-depth article here:
http://geekswithblogs.net/kobush/archive/2006/04/20/75717.aspx

Populate XDocument from String

I'm working on a little something and I am trying to figure out whether I can load an XDocument from a string. XDocument.Load() seems to take the string passed to it as a path to a physical XML file.
I want to try and bypass the step of first having to create the physical XML file and jump straight to populating the XDocument.
Any ideas?

You can use XDocument.Parse for this.

You can use XDocument.Parse(string) instead of Load(string).

How about this...?
TextReader tr = new StringReader("<Root>Content</Root>");
XDocument doc = XDocument.Load(tr);
Console.WriteLine(doc);
This was taken from the MSDN docs for XDocument.Load, found here...
http://msdn.microsoft.com/en-us/library/bb299692.aspx

Try the Parse method.