Errata

For Extension method example
The function called SquareIt is returning doubled value instead of Squared Value

//Error here
public static int SquareIt(this int num)
{
return num*2;
}

//Should be
public static int SquareIt(this int num)
{
return num*num;
}

Note from the Author or Editor:
Yes, this was a typo on my part. I originally made the method a DoubleIt() method and it was obviously overlooked in the reviews since it was not the main focus.

Thanks for making note of it. I will have it fixed for the next printing.

In chapter 6 there is an error in the VB code dealing with interfaces. In the classes that implement the INorthwindService interface the implements statement is missing. This is only missing in the C# code.

This problem only exists in the book in example 6-5. The source code for this chapter does not have this issue.

The FindProducts function should look like this ...

Public Function FindProduct(ByVal productId As Integer) As Products Implements INorthwindService.FindProduct

...
...
...

End Function
End Class

As a side note, I believe this happened when I converted just the snippet of code for example 6-5 from C# to VB using Instant VB. When I converted the entire project using the same tool, it worked great. But when converting a snippet, sometimes the tools cannot figure out the entire context for the conversion.