Re: confusion on interface IDataReader

As an adjuct (hopefully not to confuse the issue), you can certainly define
a method (or property) in .NET that returns an interface:

IDataReader GetDataReader()
{
  // ...
}

You can't return an instance of an IDataReader, but have to return a
reference to an object that supports IDataReader:

IDataReader GetDataReader()
{
  // ...
  SqlDataReader rdr = cmd.ExecuteReader();

  // An implicit cast from SqlDataReader to IDataReader is done here
  return rdr;

  // You could also (to make the code a little more readable:
  // return (IDataReader) rdr;
  //  - or -
  // return rdr as IDataReader;

}

That's perfectly valid, but I understand your confusion...

Thanks,

Shawn Wildermuth
http://adoguy.com
C# MVP, MCSD.NET, Author and Speaker

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