Microsoft has never been a slacker in the C++ department – they’ve always worked hard to provide a top-notch, compliant product. Visual Studio 10 supports their current incarnation, and for the most part it is up to their usual standards. It’s a great development environment, and I am a dedicated user, but I have to give Microsoft a demerit in one area: their C++11 hash containers have some serious performance problems – so much that the Debug versions of the containers may well be unusable in your application.
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One of the first articles I wrote for Dr. Dobb’s Journal, LZW Data Compression, turned out to be very popular, and still generates a fair amount of traffic and email over twenty years later.

One of the reasons for its popularity seems to be that LZW compression is a popular homework assignment for CS students around the world. And that audience sometimes found the article to be bit of a struggle. My code was modeled on the UNIX compress program, which was written in terse C for maximum efficiency. And sometimes optimization comes at the expense of comprehension.

By using C++ data structures I can model the algorithm in a much more straightforward way – the language doesn’t get in the way of a clear implementation. And after 20 years of answering puzzled queries I think I can improve on the overall explanation of just how LZW works.

In this updated look at LZW, I will first give a description of how LZW works, then describe the core C++ code that I use to implement the algorithm. I’ll then walk you through the use of the algorithm with a few varieties of I/O. Finally, I’ll show you some benchmarks.
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In a previous post I showed you how we use DNS Service Discovery in a product I work on for Cisco Systems. That project uses the Avahi browser, which does not have a Windows port. In this article, I’ll show you how to perform service discovery on Windows using Apple’s Bonjour SDK for Windows.
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For most of this year I’ve been working on a new product called Cisco OnPlus, a network management service for small business. In order to do its job effectively, OnPlus needs to know what devices are present on the network, and one of the key tools we use to accomplish this is DNS Service Discovery. In this article I will show you a little bit about how we use DNS-SD, and show you how you can put it to work effectively in your networks.
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The container classes included in the C++ standard library serve as good illustrations of both the strengths and the weaknesses of the language. The strengths are obvious: efficient, type-safe containers with performance guarantees suitable for a huge variety of applications. And the weaknesses? Compiler error messages that redefine the term useless, and documentation that makes a mockery of the word.

In this article I’ll illustrate how you might bump into these problems using the unordered_map container, as well showing you how to work past the problems. By rights this basic hash map should be the first- or second-most used container in your arsenal, but if you are less than a C++ savant, you might find yourself ditching it out of frustration.
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One of the great things about C, and even more so for C++, is its strong type checking mechanisms. In general a lot of bugs are caught at compile time, and experienced programmers are able to recognize and fix these types of errors quickly.

Unfortunately, there are plenty of places in any C program where type checking disappears. The GNU C compiler, gcc, goes above and beyond the call of duty to help in these areas. But sometimes that help can be a can of worms all of its own.
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In my last post I showed a particularly easy way to to set up an SMTP server so postfix could send mail from your Linux system. In this post I’m going to add a few tips that might help you get through some rough spots in the whole process.
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Getting a new computer can be interesting. My recent purchase of a Dell XPS notebook came with a few problems that I didn’t anticipate, including:

• The video hardware is not properly supported under Linux – my fault for not checking up on this.
• The backlit keyboard is an ergonomic catastrophe. When viewed under bright light, the translucent legends on light brown keycaps literally disappear. I got Dell to replace this with a non-backlit keyboard, problem solved.
• The traditional numeric keypad control keys, including arrows, Page Up/Down, Delete, and Home, have all been reduced in size and moved to random new locations. Since the notebook I bought is the size of a small car there was really no good reason for this, and it will probably take six months for my fingers to get used to the new locations.
• Under Windows, the Bluetooth driver has some sort of glitch that causes Word to crash – go figure that one out. This was resolved by disabling an addin that I wasn’t likely to ever use anyway.
• Under Linux the Bluetooth driver makes my wireless mouse nearly unusable. However, turning off Bluetooth also turns off wireless networking. I feel like there is a solution to this out there somewhere, I just have to find it.

None of these problems are going to ruin my life, but they definitely contributed to a small feeling of buyer’s remorse which I am still trying to shake off.
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For most of the thirty-some years that I’ve been paid to program, I’ve worked with Assembly language, C, or C++. There have been some diversions to Java, which is pretty painless for a C++ programmer, and always the odd short job or two in anything from Perl to Haskell.

But for the last three months or so I’ve been working full time on a short-timeline project that is using PHP as a general-purpose scripting language. So I’ve been working in this unfamiliar language at a fairly frantic pace, and I have to say that PHP, like Perl, is a strange place for a C programmer.
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Back in the day the Sapir-Whorf hypothesis was all the rage in the study of linguistics. With apologies to those who actually work in the field, I’ll crudely summarize it as the idea that the language you speak both constrains and influences how you think. The idea says that if your language only has one word for snow, for example, you will actually have a hard time seeing any difference between light powder and crunchy ice pack.

Sapir-Whorf was seen as completely discredited back when I learned about it, and while Linguistic Relativity has enjoyed a slight comeback with a weakly restated set of hypotheses, it seems fairly certain that human thought is by no means confined to a cage built out of vocabulary and grammar.

Our field has long had its own Sapir in E.W. Dijkstra, whoe spelled it out with money quotes like these:
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