Errata

When I coded the console version of the stopwatch, sometimes the elapsed time printed several times when the watch was started. This also happens when I run the downloaded solution, the text below is from the first stopwatch solution, without the pause feature.

00:00:07.400:00:00.700:00:00.700:00:00.700:00:00.600:00:00.600:00:00.6

This happens intermittently, and I had to run the author's solution a few times before it presented.

When I tried stepping through StopwatchView.WriteCurrentTime(), execution did not proceed to the next line as expected, it sometimes jumped up a line or two, or executed the same line repeatedly. Did some research, and a post at stackoverflow provided the solution: it has to do with the timer running in a different thread from the view.

The solution offered, which seems to work for me, is to start the watch with an infinite period, so it executes only once:

_timer = new Timer(timerCallback, null, 0, Timeout.Infinite);

The change it in UpdateTimeCallback(), the callback method, *after* the writes to the console. When changed, the period is set to infinite again:

_timer.Change(10, Timeout.Infinite);

Which makes sense—it’s exactly like safely upcasting versus downcasting, which you learned about in
Chapter 6: we can use assignment to downcast, but we need to use the is keyword to safely upcast. So how do we safely upcast our List<Duck> to a List<Bird>?

The line "we can use assignment to downcast, but we need to use the is keyword to safely upcast".
Isn't it the other way around? We can use assignment to upcast, but we need to use the is keyword to safely downcast.

It's impossible to add ListBoxItems from the Properties/Collection Editor menu without VS throwing an exception. You need to enter each ListBoxItem manually in the XAML editor, or else, it simply won't work.

isn't
"15. The four whole-number types that only hold positive numbers"
just
"15. The whole-number types that only hold positive numbers" or "15. The four byte of whole-number types that only hold positive numbers"?

isn't
"15. The four whole-number types that only hold positive numbers"
just
"15. The whole-number types that only hold positive numbers" or "15. The four byte of whole-number types that only hold positive numbers"?

"new public void ReturnContents(Jewels safeContents, Owner owner)" should be "new protected void ReturnContents(string safeContents, SafeOwner owner)" to be matched to the explanation.

This is on Page 8 of the Downloadable Hide and Seek exercise from chapter 10. After adding all of the rooms to the Test Initialize Method, the Assert should show a Count of 12, not 10.

In the method
public SpeakThreeTimes(Dog dog)
{
int i;
for(i= 0, i < 5, i++)
dog.Speak();
}
it should be i < 3. Otherwise the dog will speak 5 times, not three.