创建一个真正的随机 [英] Creating a true random

问题描述

可能重复:
为什么我的随机数生成器在C#中不是随机的吗?
如何生成真实(非伪)随机带有C#的数字?

Possible Duplicate:
Why does it appear that my random number generator isn't random in C#?
How can I generate truly (not pseudo) random numbers with C#?

我创建了一个骰子游戏，其中骰子基于1-100的百分位数.

I've created a dice game where the dice is based on a percentile, 1-100.

public static void Roll()
{
    Random rand = new Random((int)DateTime.Now.Ticks);
    return rand.Next(1, 100);
}

但是我不认为这是基于当前时间的真正随机值.

But I don't feel like it's a real random based on current time.

如果我这样做

for (int i = 0; i < 5; i++)
{
   Console.WriteLine("#" + i + " " + Roll());
}

它们都是相同的值，因为DateTime.Now.Ticks不变，因此种子相同的数字.

They would all be the same values, because the DateTime.Now.Ticks didn't change, it seeded the same number.

我本来以为如果当前时间种子相同，那么我可以生成一个新的随机种子，但是感觉不像是诚实的重新滚动"

I was thinking I could generate a new random seed if the seed was the same due to the current time, but it doesn't feel like an honest "re-roll"

我应该怎么做才能复制接近真实/诚实的骰子骰?我应该使用RNGCryptoServiceProvider类代替吗?

What should I do to try and replicate a close to real/honest dice roll? Should I use the RNGCryptoServiceProvider class to generate rolls instead?

推荐答案

DateTime.Now.Ticks的分辨率仅为

DateTime.Now.Ticks only has a resolution of approximately 16ms, so if you create a Random with that overload multiple times within a 16ms "slot" they will all be seeded with the same value and therefore you will get the same sequence.

在循环外初始化Random以便生成单个Random序列，而不是每次在循环内创建它都可能导致Randoms用相同的值播种并产生相同的序列

Initialize your Random outside your loop so that a single Random sequence is produced, rather than creating it each time within the loop which could result in Randoms being seeded with the same value and so produce the same sequence.

更新

我先前的观点是，默认构造函数使用CPU ticks初始化了Random，这是不正确的，默认构造函数实际上使用了

My previous point that the default constructor initialized Random with CPU ticks was incorrect, the default constructor actually uses Environment.TickCount which is:

一个32位带符号整数，其中包含自上次启动计算机以来经过的时间(以毫秒为单位).

A 32-bit signed integer containing the amount of time in milliseconds that has passed since the last time the computer was started.

哪个分辨率仍然较低.如果快速连续创建多个Random实例，则可以在同一时隙内轻松创建它们，因此它们具有相同的种子值，并创建相同的序列.创建Random的单个实例并使用它.

Which still has a low resolution. If you make multiple instances of Random in quick succession, they can easily be created within the same time slot and therefore have the same seed value, and create the same sequence. Create a single instance of Random and use that.

更新

在您的评论之前，如果您希望跨多个线程生成随机序列，请参阅下面的Jon Skeet文章，其中讨论了线程安全包装器:

Further to your comments, if you wish to generate a random sequence across multiple threads, please see the following Jon Skeet article which discusses a thread-safe wrapper:

https://codeblog.jonskeet.uk/2009/11/04/重访随机性

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