The Old New Thing

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Why was there a red telephone at every receptionist desk?

Apr 14, 2026

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Why was there a red telephone at every receptionist desk?

Raymond Chen

Not a direct line to Bill Gates's office.

Finding a duplicated item in an array of <VAR>N</VAR> integers in the range 1 to <VAR>N</VAR> − 1

Apr 13, 2026

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Finding a duplicated item in an array of N integers in the range 1 to N − 1

Raymond Chen

Taking advantage of special characteristics of the array.

How do you add or remove a handle from an active <CODE>Wait­For­Multiple­Objects</CODE>?, part 2

Apr 10, 2026

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How do you add or remove a handle from an active Wait­For­Multiple­Objects?, part 2

Raymond Chen

Waiting for the waiting thread to acknowledge the change.

How do you add or remove a handle from an active <CODE>Wait­For­Multiple­Objects</CODE>?

Apr 9, 2026

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How do you add or remove a handle from an active Wait­For­Multiple­Objects?

Raymond Chen

You can't, but you can cooperate with the other thread.

How do you add or remove a handle from an active <CODE>Msg­Wait­For­Multiple­Objects</CODE>?

Apr 8, 2026

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How do you add or remove a handle from an active Msg­Wait­For­Multiple­Objects?

Raymond Chen

You can't, but you can arrange for the waiter to do it for you.

Were there any Windows 3.1 programs that were so incompatible with Windows 95 that there was no point trying to patch them?

Apr 7, 2026

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Were there any Windows 3.1 programs that were so incompatible with Windows 95 that there was no point trying to patch them?

Raymond Chen

The permanently ineligible list.

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

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

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

Tempting but misleading.

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