What does default construction mean? Why do we write default constructors? When and why should we require them? I’ve been pondering these questions lately. One of the great things that C++ gets right is that it grants programmers the ability to create types that behave like built-in types. Many languages don’t offer this feature, treating… Continue reading Thoughts on Default Construction
Category: C++
Development of an Algorithm
Here’s an exercise: given a nice piece of code sitting in a file, how do you take that code and make it generic, in the style of an STL algorithm? For our example, let’s consider an algorithm that isn’t (yet) in the STL. First, the problem it solves. Imagine that you have a set (in… Continue reading Development of an Algorithm
C++17 Class Templates: Deduced or Not?
C++17 introduces class template deduction: a way for the compiler to deduce the arguments to construct a class template without our having to write a make_* function. But it’s not quite as straightforward as it seems. Imagine we have a simple type that will tell us when it’s copied or moved, just for testing. struct… Continue reading C++17 Class Templates: Deduced or Not?
CHRONO + RANDOM = ?
Being a quick sketch combining <chrono> and <random> functionality, with cryptarithmetic interludes… At CppCon this year there were several good talks about randomness and time calculations in C++. On randomness: Walter Brown’s What C++ Programmers Need to Know About Header <random> and Cheinan Marks’ I Just Wanted a Random Integer! were both excellent talks. And… Continue reading CHRONO + RANDOM = ?
An algorithmic sketch: inplace_merge
One of the things I like to do in my spare time is study the STL algorithms. It is easy to take them for granted and easy, perhaps, to imagine that they are mostly trivial. And some are: I would think that any decent interview candidate ought to be able to write find correctly. (Although… Continue reading An algorithmic sketch: inplace_merge
Lameness Explained
OK, more than one person wanted explanations of The C++ <random> Lame List, so here are some of my thoughts, if only to save people searching elsewhere. Calling rand() is lame because it’s an LCG with horrible randomness properties, and we can do better. And if you’re not calling rand(), there’s no reason to call… Continue reading Lameness Explained
The C++ <random> Lame List
Network programmers of a certain age may remember the Windows Sockets Lame List. I previously wrote a short “don’t-do-that-do-this” guide for modern C++ randomness, and I was recently reading another Reddit exchange featuring STL, author of many parts of Microsoft’s STL implementation, when it struck me that use of C++ <random> needs its own lame… Continue reading The C++ <random> Lame List
Compile-time RNG tricks
(Start at the beginning of the series – and all the source can be found in my github repo) Compile-time random number generation is quite useful. For instance, we could generate GUIDs (version 4 UUIDs): namespace cx { struct guid_t { uint32_t data1; uint16_t data2; uint16_t data3; uint64_t data4; }; template constexpr guid_t guidgen() {… Continue reading Compile-time RNG tricks
Compile-time counters, revisited
(Start at the beginning of the series – and all the source can be found in my github repo) Some time ago I read a blog post showing how to make a compile-time counter: a constexpr function that would return monotonically increasing integers. When I first read it I didn’t really take the time to… Continue reading Compile-time counters, revisited
More string hashing with C++11 constexpr
(Start at the beginning of the series – and all the source can be found in my github repo) So FNV1 was easy, and Murmur3 wasn’t too much harder; for a challenge and to see how far I could go, I decided to try to compute an MD5 string hash using C++11 constexpr. This was… Continue reading More string hashing with C++11 constexpr