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They're still there, just in a different guise.

As we noted last time, structure tags are different from the typedef name as a historical artifact of earlier versions of the C language. But what about just leaving out the name entirely? One problem with this approach is that it becomes impossible to make a forward reference to this structure because it has no name. For example, if you wanted...

In Windows header files, many structures are declared like this: Why is the structure name different from typedef name? This is a holdover from very early versions of the C language where structure tags, union tags, and typedefs were kept in the same namespace. Consequently, you couldn't say . At the open brace, the compiler registers as a s...

When you go through Windows header files, you'll see types with names , , , and so on. What's the difference between these types and the uncapitalized ones? Well, there isn't one any more. What follows is an educated guess as to the story behind these types. The application binary interface for an operating system needs to be unambiguous. Everyb...

Not much any more.

Suppose you have a string of the form . How can you parse this into something your program can manipulate, like say a or a ? Basically, you can't in the general case. The time zone abbreviation CST is ambiguous. It could mean U.S./Canada Central Standard Time, Australian Central Standard Time, China Standard Time, or Cuba Summer Time. There ma...

On Windows NT-based operating systems, process and thread IDs happen always to be a multiple of four. Is this just a coincidence? Yes, it's just a coincidence, and you shouldn't rely on it since it is not part of the programming contract. For example, Windows 95 process and thread IDs were not always multiples of four. (By comparison, th...

Making the last change.

Commenter Adam Russell asks why Ctrl+ScrollLock cancels dialogs. Easy. Because Ctrl+ScrollLock is the same as Ctrl+Break, and Ctrl+Break cancels dialogs. Okay, that answer actually raises two more questions. First, why is Ctrl+ScrollLock the same as Ctrl+Break? This is a consequence of the backward compatibility designed into the Enhanced Keyboa...

Recall that the identified a set of variables. This causes a bit of a problem if your program has multiple data segments; in other words, multiple sets of variables. In such a program, the code would load the data segment of whatever variable it needed each time it needed to access a variable from a different segment. This was no problem at all f...