Showing results for 2014 - Page 6 of 31 - The Old New Thing

Oct 28, 2014
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A question about preventing the system from going to the idle state turns out to be misguided

Raymond Chen
Raymond Chen

A customer asked how they could have their program prevent the system from going to the idle state. Specifically, when the system goes idle, the application gets into a weird state where it starts leaking memory like crazy. The program normally uses around 100MB of memory, but when the system goes idle, something funky happens and the program's mem...

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Oct 27, 2014
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Enumerating the ways of distributing n balls into k boxes

Raymond Chen
Raymond Chen

Suppose you had n indistinguishable balls and k distinguishable boxes. Enumerate the ways of distributing the balls into boxes. Some boxes may be empty. We can represent each distribution in the form of n stars and k − 1 vertical lines. The stars represent balls, and the vertical lines divide the balls into boxes. For example, here are the...

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Oct 24, 2014
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Debugging a hang: Chasing the wait chain inside a process

Raymond Chen
Raymond Chen

Today we're going to debug a hang. Here are some of the (redacted) stacks of the process. I left some red herrings and other frustrations. Since debugging is an exercise in optimism, let's ignore the stacks that didn't come out properly. If we can't make any headway, we can try to fix them, but let's be hopeful that the stacks that are good wil...

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Oct 23, 2014
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How can I detect programmatically whether the /3GB switch is enabled?

Raymond Chen
Raymond Chen

A customer was doing some diagnostic work and wanted a way to detect whether the switch was enabled. (Remember that the switch is meaningful only for 32-bit versions of Windows.) The way to detect the setting is to call and look at the . Compile this as a 32-bit program and run it. On 32-bit systems, this reports the system-wide setting...

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Oct 22, 2014
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How do I disable Windows 8 touch contact visualizations for my application?

Raymond Chen
Raymond Chen

You might have an application (like a game) where the default touch contact visualizations are a distraction. In WinRT, you can disable the contact visualizations by simply saying In Win32, you use the function. To demonstrate that, let's take our scratch program and make this simple change: The touch visualizations are white and the defau...

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Oct 21, 2014
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The great thing about regular expression languages is that there are so many to choose from!

Raymond Chen
Raymond Chen

Before you ask a question about regular expressions, you should make sure you and your audience agree on which regular expression language you are talking about. Here is a handy table of which features are supported by which regular expression language. You can use that table to solve this customer's problem: I have a regular expression th...

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Oct 20, 2014
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Scripting an Internet Explorer window

Raymond Chen
Raymond Chen

Today's Little Program takes a random walk through MSDN by starting at the page and randomly clicking links. The exercise is not as important as the technique it demonstrates. (I'm assuming the reader can figure out what language this script is written in. If you have to ask, then you probably won't understand this article at all. I am also no...

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Oct 17, 2014
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When are global objects constructed and destructed by Visual C++?

Raymond Chen
Raymond Chen

Today we're going to fill in the following chart: The C++ language specification provides some leeway to implementations on when global static objects are constructed. It can construct the object before begins, or it construct the object on demand according to complicated rules. You can read [basic.start.init] for the gory details. Let's ass...

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Oct 16, 2014
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If only DLLs can get DllMain notifications, how can an EXE receive a notification when a thread is created (for example)?

Raymond Chen
Raymond Chen

When a DLL is loaded, it receives a notification, and when it is unloaded (or when the process terminates), it gets a notification. DLLs also receive notifications when a thread is created and notifications when a thread exits. But what if you are an EXE? EXEs don't have a , so there is no way to receive these notifications. The trick here i...

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Oct 15, 2014
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The GetCurrentThread function is like a check payable to Bearer: What it means depends on who's holding it

Raymond Chen
Raymond Chen

The function returns a pseudo-handle to the current thread. The documentation goes into significant detail on what this means, but I fear that it may have fallen into the trap of providing so much documentation that people decide to skip it. Okay, so first of all, what is a pseudo-handle? a pseudo-handle is a sentinel value for that is not r...

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