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I just finished my working code, but still want to improve it.

I want to transform this input:

<item>asdf</item>
<item>asdf</item>
<item>asdf</item>

to this output:

<string name="x1">asdf</string>
<string name="x2">asdf</string>
<string name="x3">asdf</string>

My current code:

   static void Main(string[] args)
        {
            String content;

            using (StreamReader reader = new StreamReader("arrays2.xml"))
            {
                content = reader.ReadToEnd();
            }

            int counter = 0;
            int startIndex = 0;
            while ((startIndex = content.IndexOf("<item>", startIndex)) != -1)
            {
                counter++;           
                content = content.Substring(0, startIndex) + "<string name=\"rule" + counter + "\">" + content.Substring(startIndex + 6);
            }

            content = content.Replace("</item>", "</string>");


            using (StreamWriter writer = new StreamWriter("arrays2_formatted.xml"))
            {
                writer.Write(content);
            }
            Console.WriteLine(content);


        }

I think the bottleneck is in the content assignment within the loop, as a lot of String instance are created and thrown away.

However, is there a completely different way to do this efficiently?

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  • \$\begingroup\$ So, you're saying your code is too slow? Have you profiled it? How big is the file you're converting? Are you sure the code is the bottleneck and not the disk? \$\endgroup\$ – svick May 6 '12 at 9:00
  • \$\begingroup\$ @svick No, I don't claim anything. I just want to improve it, as I am not a c# developer, normally. :) \$\endgroup\$ – Michael May 6 '12 at 12:14
3
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Don't parse it through string manipulation, use the XML libraries in the framework. I'd recommend LINQ to XML. Parse it and make your changes.

var xmlStr = @"<root>
<item>asdf</item>
<item>asdf</item>
<item>asdf</item>
</root>";

var doc = XDocument.Parse(xmlStr);         // parse from string
//var doc = XDocument.Load("arrays2.xml"); // or load from file
var items = doc.Descendants("item");       // find all item elements
var index = 1;
foreach (var item in items.ToList())  // ToList() required since we're modifying the document
{
    var name = "x" + index++;
    var nameAttr = new XAttribute("name", name);           // create the name attribute
    var value = (string)item;                              // read the value as a string
    var newNode = new XElement("string", nameAttr, value); // create the new element
    item.ReplaceWith(newNode);                             // replace the current one
}
//doc.Save("arrays2_formatted.xml"); // save the changes to the file
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  • \$\begingroup\$ Note, your "XML" is not valid XML, it needs a root. \$\endgroup\$ – Jeff Mercado May 6 '12 at 8:27

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