如何保存在C＃随机生成器的状态？ [英] How to save the state of a Random generator in C#?

问题描述

有关测试目的我正在与一个给定的种子产生的随机数（即，不是基于当前时间）。

For testing purposes I'm creating random numbers with a given seed (i.e. not based on the current time).

因此​​，整个程序是确定性的。

Thus the whole program is deterministic.

如果有事，我希望能够在事件前不久快速恢复的一个点。

If something happens, I'd like to be able to quickly restore a point "shortly before" the incident.

因此，我需要能够恢复 System.Random 到以前的状态。

Therefore I need to be able to restore a System.Random to a previous state.

有一个方法来提取的种子，我可以用它来重新创建随机数发生器？

Is there a way to extract a seed which I can use to recreate the random generator?

推荐答案

在与answer 这里给出的，我写了一个小班，以帮助保存和恢复状态。

In line with the answer given here, I wrote a small class to help with saving and restoring the state.

void Main()
{
    var r = new Random();

    Enumerable.Range(1, 5).Select(idx => r.Next()).Dump("before save");
    var s = r.Save();
    Enumerable.Range(1, 5).Select(idx => r.Next()).Dump("after save");
    r = s.Restore();
    Enumerable.Range(1, 5).Select(idx => r.Next()).Dump("after restore");

    s.Dump();
}

public static class RandomExtensions
{
    public static RandomState Save(this Random random)
    {
        var binaryFormatter = new BinaryFormatter();
        using (var temp = new MemoryStream())
        {
            binaryFormatter.Serialize(temp, random);
            return new RandomState(temp.ToArray());
        }
    }

    public static Random Restore(this RandomState state)
    {
        var binaryFormatter = new BinaryFormatter();
        using (var temp = new MemoryStream(state.State))
        {
            return (Random)binaryFormatter.Deserialize(temp);
        }
    }
}

public struct RandomState
{
    public readonly byte[] State;
    public RandomState(byte[] state)
    {
        State = state;
    }
}

您可以测试的 LINQPad 。

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