Some numbers are easier to work with than others, especially for computer arithmetic—and even more so with weak processors. So let’s have a look at easy numbers that we can sometimes exploit to get faster code.
Last week, we had a look at how to implement a trool, or a tri-valued boolean what accepts true, false, and undefined. We remarked that the storage of an enum likely defaults to int, and that my poc wouldn’t play well with std::vector as that container has no specialization to deal with this new type.
A specialization would be interesting because we can do much better than using an integer to store three different values. We can do much, much better.
Initializing arrays, or any variable for that matter, is always kind of a problem. Most of the times, you can get away with a default value, typically zero in C#C++, but not always. For floats, for example, NaN makes much more sense. Indeed, it’s initialized to not a number: it clearly states that it is initialized, consciously, to not a value. That’s neat. What about integers? Clearly, there’s no way to encode a NaI (not an integer), maybe std::numeric_limits::min(), which is still better than zero. What about bools?
Bool is trickier. In C++, bool is either false or true, and weak typing makes everything not zero true. However, if you assign 3 to a bool, it will be “normalized” to true, that is, exactly 1. Therefore, and not that surprisingly, you can’t have true, false, and maybe. Well, let’s fix that.
Recently on Freenode channel ##cpp, I saw some code using an include-all-you-can header. The idea was to help beginners to the language, help them start programming without having to remember which header was which, and which headers are needed.
Is that really a good idea?
About a week ago, some dude drops on IRC that he’s beat memcpy “by a lot”. That’d be interesting, except that we couldn’t get neither code nor test methodology out of him. But, how hard can making a better memcpy be? Turns out, harder than you think!
If you think this is a typical case of “reinventing the wheel”, I mostly agree with you. But while reinventing will be hard, can improvements be made?
There’s no easy way of getting a console-based color output with standard C++. Of course, you can use ncurse, which does pretty much everything, but that is also quite tedious to use. But if you need just a little bit of color, ncurse is pretty overkill. Fortunately, if you have an ANSI capable terminal, that’s much easier.