The Old New Thing

Code - The Old New Thing

How can I get information about the items in the Recycle Bin?

August 30, 2011 Aug 30, 2011 08/30/11
Raymond Chen
For some reason, a lot of people are interested in programmatic access to the contents of the Recycle Bin. They never explain why they care, so it's possible that they are looking at their problem the wrong way. For example, one reason for asking, "How do I purge an item from the Recycle Bin given a path?" is that some operation in their ...

Why can't I use PSGUID_STORAGE like a GUID?

August 29, 2011 Aug 29, 2011 08/29/11
Raymond Chen
The header file defines a GUID called , but a customer was having trouble using it. The strange compiler error the customer referred to is the following: "I don't see what the compiler is complaining about. The parentheses appear to be properly matched before the left brace." Remember, what you see is not necessarily what the ...

Stupid command-line trick: Counting the number of lines in stdin

August 25, 2011 Aug 25, 2011 08/25/11
Raymond Chen
On unix, you can use to count the number of lines in stdin. Windows doesn't come with , but there's a sneaky way to count the number of lines anyway: It is a special quirk of the command that the null string is treated as never matching. The flag reverses the sense of the test, so now it matches everything. And the flag returns the ...

The ways people mess up IUnknown::QueryInterface, episode 4

August 11, 2011 Aug 11, 2011 08/11/11
Raymond Chen
One of the rules for is so obvious that nobody even bothers to state it explicitly as a rule: "If somebody asks you for an interface, and you return , then the pointer you return must point to the interface the caller requested." (This feels like the software version of dumb warning labels.) During compatibility testing for Windows ...

Menu item states are not reliable until they are shown because they aren't needed until then

August 5, 2011 Aug 5, 2011 08/5/11
Raymond Chen
A question arrived from a customer (with the rather unhelpful subject line Question for Microsoft) wondering why, when they call and then ask for the states of the various menu items like , the menu item states don't reflect reality. The menu item states don't synchronize with reality until the user actually opens the system menu. There is ...

Why doesn't b match word boundaries correctly?

August 4, 2011 Aug 4, 2011 08/4/11
Raymond Chen
A colleague of mine was having trouble getting the metacharacter in a regular expression to work. Of course, when somebody asks a question like that, you first have to establish what their definition of "work" is. Fortunately, he provided some examples: "The last two entries are just sanity checks to make sure I didn't make some stupid ...