You're probably all familiar with the feature of C# which disallows reading from a local variable before it has been "definitely assigned": void M() { int x; if (Q()) x = 123; if (R()) Console.WriteLine(x); // illegal! } This is illegal because there...

I am super excited to announce that the beta release of Visual Studio version 11 (which includes the .NET CLR version 4.5, Visual Basic version 11 and C# version 5) is available for download right now. As you know if you've been following our CTP releases...

The first time I ran my histogram visualizer I asked for a Cauchy distribution with a minimum of -10 and a maximum of 10, and of course I got a graph that looks much like the one from my article of last week: Looks perfectly reasonable; I guess my program...

My original version of the histogram-generating code that I whipped up for the previous episode of FAIC contained a subtle bug. Can you spot it without going back and reading the corrected code? private static int[] CreateHistogram(IEnumerable<double>...

When building simulations of real-world phenomena, or when generating test data for algorithms that will be consuming information from the real world, it is often highly desirable to produce pseudo-random data that conform to some nonuniform probability...

The standard way to teach beginner OO programmers about classes is to make a metaphor to the real world. And indeed, I do this all the time in this blog, usually to the animal kingdom. A "class" in real life codifies a commonality amongst a certain set...

"Late binding" is one of those computer-sciency terms that, like "strong typing", means different things to different people. I thought I might describe what the term means to me. First off, what is "binding"? We can't understand what it means to bind...

Today, yet another episode in my ongoing series " What's the difference? " This time, a non-computer-related topic . I am often complimented on my choice of outerwear in the Seattle rainy season, and I hate to respond to a well-meant compliment with a...

Last time I noted that any two usages of "the same" anonymous type within an assembly actually unify to be the same type. By "the same" we mean that the two anonymous types have the same property names and types, and that they appear in the same order...

Back in my last post of 2010 I said that I would do an example of anonymous types unifying within an assembly "in the new year". I meant 2011, but here we are "in the new year" again, so, no time like the present. The C# specification guarantees you that...

If you ask a dozen C# developers what a "local variable" is, you might get a dozen different answers. A common answer is of course that a local is "a storage location on the stack". But that is describing a local in terms of its implementation details;...

Here's an inconvenient truth: just about every "public surface area" change you make to your code is a potential breaking change. First off, I should clarify what I mean by a "breaking change" for the purposes of this article. If you provide a component...

Happy New Year all! It has just been brought to my attention that this blog and the Programmer Ryan Gosling photo blog share at least one reader: I admit it, I LOL'd. In the interests of total accuracy I'd like to point out that the first entry on the...

OK, let's finish up this year and this series. We have an algorithm that can compute what cells in the zero octant are in view to a viewer at the origin when given a function that determines whether a given cell is opaque or transparent. It marks the...

I hope you all had a pleasant Christmas and Boxing Day; we chose to not travel to see family this year and had a delightful time visiting friends. We'll finish up 2011 here with a bit more on shadowcasting, and then pick up with more C# language design...

Last time we saw how many different ways there were to get the calculation of the top cell based on the top vector wrong. Today we'll take a briefer look at determining the bottom cell. We know from our discussion of last time that the right way to determine...

Before we get started, thanks for all the great comments to the previous couple of posts. I'll be updating the algorithm to try to make even better-looking circles of light based on the comments. Like I said, there's a lot of subtleties to these algorithms...

I hope the basic idea of the shadow casting algorithm is now clear. Let's start to implement the thing. There are two main concerns to deal with. The easy one is "what should the interface to the computation look like?" The second is "how to implement...

I've always loved the "roguelike" games; perhaps you've played some of them. Those are the games where you get a top-down view of a tile-based world, and have as much real time as you like to make a choice of action. The canonical plot is to enter a dungeon...

No technology today. Rather, some advice. I don't know if there's some sort of grifter convention going on, but I have seen four different short-con artists operating in Wallingford, the neighbourhood of Seattle where I live, in the last three days. Though...

In my earlier article from April 2011 on interface implementation I noted that C# supports a seldom-used feature called "interface re-implementation". This feature is useful when you need it but unfortunately is one of those features that can bite you...

Today, another episode of my ongoing series " What's the difference? " Today, what's the difference between a remainder and a modulus, and which, if either, does the % operator represent in C#? A powerful idea that you see come up in mathematics...

Last time I discussed why it is that we have all the .NET compilers target an "intermediate language", or "IL", and then have jitters that translate IL to machine code: because doing so ultimately reduces the costs of building a multi-language, multi...

One of the earliest and most frequently-asked questions we got when we announced the Roslyn project was "is this like LLVM for .NET?" No, Roslyn is not anything like LLVM for .NET. LLVM stands for Low-Level Virtual Machine ; as I understand it (admittedly...

Just a couple of quick links today. First: One of the questions I get most frequently is " can you recommend some good books about learning to program better in C#? " The question is usually asked by a developer; the other day I was surprised to get...