The Old New Thing

If you want to use a name for your file mapping, don’t just use the name of the file itself

May 10, 2013 May 10, 2013 05/10/13

Raymond Chen

The original question from the customer was why they couldn't get named file mappings to work at all, but it turns out that the reason is that they were using the full path to the file as the name, even though backslashes have special meaning in file mapping names. Okay, that problem can be solved by changing the backslash to some character...

Why am I getting LNK2019 unresolved external for my inline function?

May 9, 2013 May 9, 2013 05/9/13

Raymond Chen

More than once, I've seen somebody confused by how inline functions work. I have implemented a few inline functions in one of my cpp files, and I want to use it from other cpp files, so I declare them as extern. But sometimes I will get linker error 2019 (unresolved external) for the inline functions. // a.cpp inline bool foo() { return ...

Mathematical formulas are designed to be pretty, not to be suitable for computation

May 8, 2013 May 8, 2013 05/8/13

Raymond Chen

When you ask a mathematician to come up with a formula to solve a problem, you will get something that looks pretty, but that doesn't mean that it lends itself well to computation. For example, consider the binomial coefficient, traditionally written nCk or C(n, k), and in more modern notation as ( nk ). If you ask a ...

Reading mouse input from a console program, and programmatically turning off Quick Edit mode

May 6, 2013 May 6, 2013 05/6/13

Raymond Chen

Today's Little program shows how to read mouse input from a console program. You might use this if you are writing a console-mode text editor with mouse support, or maybe you want to want to add mouse support to your roguelike game. But I'm not going to implement the game itself. Instead, I'm just going to print mouse coordinates to the ...

Creating a simple pidl: For the times you care enough to send the very fake

May 3, 2013 May 3, 2013 05/3/13

Raymond Chen

I'll assume that we all know what pidls are and how the shell namespace uses them. That's the prerequisite for today. A simple pidl is an item ID list that refers to a file or directory that may not actually exist. It's a way of playing "what if": "If there were a file or directory at this location, here is what I would have created to ...

How do I get the current value of the RSP register from a C/C++ function? (No answer, but a solution.)

May 1, 2013 May 1, 2013 05/1/13

Raymond Chen

A customer using Visual Studio wanted to know how to obtain the current value of the x64 RSP register from a C/C++ function. They noted that on the x86, you can drop to inline assembly, and on the ia64, you can use the intrinsic to retrieve the value of any register. There is no corresponding intrinsic on x64. There's no really good way of...