Question

My xml:

  <Configuration>
    <LaunchDebugger>false</LaunchDebugger>
    <RequestFolder>./Request</RequestFolder>
    <ResponseFolder>./Response</ResponseFolder>
    <Countries>
      <Country NumericCode="1FH" FileName="file1.xml">1</Country>
      <Country NumericCode="20H" FileName="file2.xml">2</Country>
      <Country NumericCode="" FileName="file3.xml">3</Country>
    </Countries>
  </Configuration>

Country class:

public class Country
{
    public String Name { get; set; }
    public String NumericCode { get; set; }
    public String FileName { get; set; }
}

This is how i create objects from it using LINQ:

    CountryList = (from filter in Configuration.Descendants("Countries").Descendants("Country")
                    select new Country() 
                    {
                        Name = (string)filter.Value,
                        NumericCode = (string)filter.Attribute("NumericCode"),
                        FileName = (string)filter.Attribute("FileName")
                    }).ToList();

Parsing xml works, i get all 3 countries in my list, but i also get one extra null object as the last item of the list.

Any idea why that would be happening?

Answer 1

Reason is simple – List<T> has default capacity equal to 4. Capacity gets or sets the total number of elements the internal data structure can hold without resizing. Internal data structure is a simple array private Country[] _items, which is initially has length equal to 4. Thus there is reserved place for forth element, which is null until element assigned. But don’t worry – elements count will be 3 if you check.

Here is an image, which shows both public (three items) and internal data structure (array of capacity size)