The Old New Thing

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Learning to read C++ compiler errors: Illegal use of <TT>-></TT> when there is no <TT>-></TT> in sight

Apr 6, 2026

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Learning to read C++ compiler errors: Illegal use of -> when there is no -> in sight

Raymond Chen

Raymond Chen

If the compiler is complaining about things you didn't write, find out who wrote them.

How can I use <CODE>Read­Directory­ChangesW</CODE> to know when someone is copying a file out of the directory?

Apr 3, 2026

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How can I use Read­Directory­ChangesW to know when someone is copying a file out of the directory?

Raymond Chen

Raymond Chen

File copying is not a fundamental operation, nor is it even detectable at the file system layer.

Why doesn’t the system let you declare your own messages to have the same semantics as <CODE>WM_<WBR>COPY­DATA</CODE>?

Apr 2, 2026

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Why doesn’t the system let you declare your own messages to have the same semantics as WM_COPY­DATA?

Raymond Chen

Raymond Chen

Tempting but misleading.

The cover of <I>C++: The Programming Language</I> raises questions not answered by the cover

Apr 1, 2026

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The cover of C++: The Programming Language raises questions not answered by the cover

Raymond Chen

Raymond Chen

What are we reading about here?

Before you check if an update caused your problem, check that it wasn’t a problem before the update

Mar 31, 2026

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Before you check if an update caused your problem, check that it wasn’t a problem before the update

Raymond Chen

Raymond Chen

It was going to be like that when I got here.

A question about the maximimum number of values in a registry key raises questions about the question

Mar 30, 2026

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A question about the maximimum number of values in a registry key raises questions about the question

Raymond Chen

Raymond Chen

Why is this even a question?

What if a dialog wants to intercept its own message loop?

Mar 27, 2026

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What if a dialog wants to intercept its own message loop?

Raymond Chen

Raymond Chen

You can steal them from your owner.

Why doesn’t <CODE>WM_<WBR>ENTER­IDLE</CODE> work if the dialog box is a <CODE>Message­Box</CODE>?

Mar 26, 2026

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Why doesn’t WM_ENTER­IDLE work if the dialog box is a Message­Box?

Raymond Chen

Raymond Chen

Because it opted out.

How can I change a dialog box’s message loop to do a <CODE>Msg­Wait­For­Multiple­Objects</CODE> instead of <CODE>Get­Message</CODE>?

Mar 25, 2026

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How can I change a dialog box’s message loop to do a Msg­Wait­For­Multiple­Objects instead of Get­Message?

Raymond Chen

Raymond Chen

The dialog box lets you change how it waits.

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