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(),…
Author: elbeno
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++…
Amaze your friends, and confound your enemies!
When I was young, I read lots of books with titles (or at least subheadings) along the lines of, “Amaze Your Friends and Confound Your Enemies” – a lot of them were filled with tricks and oddities like the Birthday Paradox, or the old saw about the elephant from Denmark….
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; };…
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…
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…
C++11 compile-time string hashing
(Start at the beginning of the series – and all the source can be found in my github repo) Now that I was used to writing C++11-style constexpr, I decided to try some compile-time string hashing. It turns out that FNV1 is very easy to express in a move-down-the-string recursive…
More constexpr floating-point computation
(Start at the beginning of the series – and all the source can be found in my github repo) In the last post, I covered my first forays into writing C++11-style constexpr floating point math functions. Once I’d done some trig functions, exp, and floor and friends, it seemed like…
Floating-point maths, constexpr style
(Start at the beginning of the series – and all the source can be found in my github repo) To ease into constexpr programming I decided to tackle some floating-point maths functions. Disclaimer: I’m not a mathematician and this code has not been rigorously tested for numeric stability or convergence…
Experimenting with constexpr
Since seeing Scott Schurr at C++Now in Aspen and hearing his talks about constexpr, it’s been on my list of things to try out, and recently I got around to it. With the release of Visual Studio 2015, Microsoft’s compiler now finally supports C++11 style constexpr (modulo some minor issues),…