Question

I have a product database in XML. For each product I have its width W, height H and price P.

Given a product with W, H and P, I want to count the number of products with width less than W, and separate counts for those with height < H and those with price < P. Meaning 3 separate and independent numbers resulting from counting.

What is an efficient way to do so using C#? Obviously, I want to go through each element in the XML file only once.

XML file is made up of following nodes and has been read into an XDocument object:

<product><name>abc</name><W>7</W><H>3</H><P>40</P></product>

Answer 1

Something like this would work

  XDocument doc = XDocument.Parse(xml);

  int heightCount = 0;
  int widthCount = 0;
  int priceCount = 0;

  int heightThreshold = 3;
  int widthThreshold = 1;
  int priceThreshold = 1;

  foreach (var product in doc.Descendants("product"))
  {
    int height = Convert.ToInt32(product.Element("H").Value);
    int width = Convert.ToInt32(product.Element("W").Value);
    int price = Convert.ToInt32(product.Element("P").Value);

    if (height < heightThreshold)
    {
      heightCount++;
    }

    if (width < widthThreshold)
    {
      widthCount++;
    }

    if (price < priceThreshold)
    {
      priceCount++;
    }       
  }

This has no safeguards though, so if your product element does not contain an integer value for each of the H,W and P elements (or one of these elements does not exists), it will break. You’d need to add some null and conversion checking.