使用C ++ 11随机库生成随机数 [英] Generate random numbers using C++11 random library

问题描述

正如标题所示，我试图找到一种使用新的C ++ 11 <random>库生成随机数的方法.我已经用以下代码尝试过:

As the title suggests, I am trying to figure out a way of generating random numbers using the new C++11 <random> library. I have tried it with this code:

std::default_random_engine generator;
std::uniform_real_distribution<double> uniform_distance(1, 10.001);

我的代码存在的问题是，每次我编译并运行它时，它总是生成相同的数字.所以我的问题是，在真正随机的情况下，随机库中还有哪些其他函数可以完成此任务?

The problem with the code I have is that every time I compile and run it, it always generates the same numbers. So my question is what other functions in the random library can accomplish this while being truly random?

对于我的特定用例，我试图获取一个在[1, 10]

For my particular use case, I was trying to get a value within the range [1, 10]

推荐答案

Microsoft的Stephan T. Lavavej(stl)在Going Native上发表了关于如何使用新的C ++ 11随机函数以及为什么不使用rand().在其中，他包括一张幻灯片，该幻灯片基本上可以解决您的问题.我已经从下面的幻灯片中复制了代码.

Stephan T. Lavavej (stl) from Microsoft did a talk at Going Native about how to use the new C++11 random functions and why not to use rand(). In it, he included a slide that basically solves your question. I've copied the code from that slide below.

您可以在此处查看他的完整讲话: http://channel9. msdn.com/Events/GoingNative/2013/rand-Considered-Harmful

You can see his full talk here: http://channel9.msdn.com/Events/GoingNative/2013/rand-Considered-Harmful

#include <random>
#include <iostream>

int main() {
    std::random_device rd;
    std::mt19937 mt(rd());
    std::uniform_real_distribution<double> dist(1.0, 10.0);

    for (int i=0; i<16; ++i)
        std::cout << dist(mt) << "\n";
}

我们使用random_device一次来播种名为mt的随机数生成器. random_device()比mt19937慢，但是不需要种子，因为它会从您的操作系统中请求随机数据(该数据将来自各个位置，例如

We use random_device once to seed the random number generator named mt. random_device() is slower than mt19937, but it does not need to be seeded because it requests random data from your operating system (which will source from various locations, like RdRand for example).

查看此问题/答案，看来uniform_real_distribution返回了您要在[a, b]范围内的[a, b)范围内的数字.为此，我们的uniform_real_distibution实际上应如下所示:

Looking at this question / answer, it appears that uniform_real_distribution returns a number in the range [a, b), where you want [a, b]. To do that, our uniform_real_distibution should actually look like:

std::uniform_real_distribution<double> dist(1, std::nextafter(10, DBL_MAX));

这篇关于使用C ++ 11随机库生成随机数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！