Format XML string to print friendly XML string

You will have to parse the content somehow ... I find using LINQ the most easy way to do it. Again, it all depends on your exact scenario. Here's a working example using LINQ to format an input XML string.

string FormatXml(string xml)
{
     try
     {
         XDocument doc = XDocument.Parse(xml);
         return doc.ToString();
     }
     catch (Exception)
     {
         // Handle and throw if fatal exception here; don't just ignore them
         return xml;
     }
 }

[using statements are ommitted for brevity]

Use XmlTextWriter...

public static string PrintXML(string xml)
{
    string result = "";

    MemoryStream mStream = new MemoryStream();
    XmlTextWriter writer = new XmlTextWriter(mStream, Encoding.Unicode);
    XmlDocument document = new XmlDocument();

    try
    {
        // Load the XmlDocument with the XML.
        document.LoadXml(xml);

        writer.Formatting = Formatting.Indented;

        // Write the XML into a formatting XmlTextWriter
        document.WriteContentTo(writer);
        writer.Flush();
        mStream.Flush();

        // Have to rewind the MemoryStream in order to read
        // its contents.
        mStream.Position = 0;

        // Read MemoryStream contents into a StreamReader.
        StreamReader sReader = new StreamReader(mStream);

        // Extract the text from the StreamReader.
        string formattedXml = sReader.ReadToEnd();

        result = formattedXml;
    }
    catch (XmlException)
    {
        // Handle the exception
    }

    mStream.Close();
    writer.Close();

    return result;
}

This one, from kristopherjohnson is heaps better:

1. It doesn't require an XML document header either.
2. Has clearer exceptions
3. Adds extra behaviour options: OmitXmlDeclaration = true, NewLineOnAttributes = true

4. Less lines of code

   static string PrettyXml(string xml)
   {
       var stringBuilder = new StringBuilder();
   
       var element = XElement.Parse(xml);
   
       var settings = new XmlWriterSettings();
       settings.OmitXmlDeclaration = true;
       settings.Indent = true;
       settings.NewLineOnAttributes = true;
   
       using (var xmlWriter = XmlWriter.Create(stringBuilder, settings))
       {
           element.Save(xmlWriter);
       }
   
       return stringBuilder.ToString();
   }
   

The simple solution that is working for me:

        XmlDocument xmlDoc = new XmlDocument();
        StringWriter sw = new StringWriter();
        xmlDoc.LoadXml(rawStringXML);
        xmlDoc.Save(sw);
        String formattedXml = sw.ToString();