.NET' s Random()的实现更改 [英] Implementation change to .NET's Random()

问题描述

我正在将用于解码的方法从.NET Framework 1.1迁移到.NET Framework 4.我注意到随机的实现已更改.因此，给定相同的种子， Random.NextBytes 返回不同的结果结果.

I am migrating a method that is used for decoding from .NET Framework 1.1 to .NET Framework 4. I noticed that implementation of Random changed. So given the same seed, Random.NextBytes returns different result.

因此，如果我运行以下代码.

So if I run the following code.

byte[] bytes = new byte[4];
System.Random random = new System.Random(50);
random.NextBytes(bytes);

for(int i=0; i< bytes.Length; i++)
{
  Console.WriteLine("bytes[" + i + "] = " + bytes[i]);
}

在.NET Framework 1.1下，它返回:

Under .NET Framework 1.1 it returns:

bytes[0] = 216
bytes[1] = 124
bytes[2] = 183
bytes[3] =  58

在.NET Framework 4下，它返回:

Under .NET framework 4 it returns:

bytes[0] = 154
bytes[1] =  49
bytes[2] = 183
bytes[3] =  48

解决此问题的最佳方法是什么?

What is the best way to resolve this problem?

推荐答案

您可以使用Reflector从1.1 mscorlib复制Random类.

You can just use Reflector to copy the Random class from the 1.1 mscorlib.

public class Random1_1
{
    // Fields
    private int inext;
    private int inextp;
    private const int MBIG = 0x7fffffff;
    private const int MSEED = 0x9a4ec86;
    private const int MZ = 0x0;
    private int[] SeedArray;

    // Methods
    public Random1_1()
        : this(Environment.TickCount)
    {
    }

    public Random1_1(int Seed)
    {
        this.SeedArray = new int[0x38];
        int num2 = 0x9a4ec86 - Math.Abs(Seed);
        this.SeedArray[0x37] = num2;
        int num3 = 0x1;
        for (int i = 0x1; i < 0x37; i++)
        {
            int index = (0x15 * i) % 0x37;
            this.SeedArray[index] = num3;
            num3 = num2 - num3;
            if (num3 < 0x0)
            {
                num3 += 0x7fffffff;
            }
            num2 = this.SeedArray[index];
        }
        for (int j = 0x1; j < 0x5; j++)
        {
            for (int k = 0x1; k < 0x38; k++)
            {
                this.SeedArray[k] -= this.SeedArray[0x1 + ((k + 0x1e) % 0x37)];
                if (this.SeedArray[k] < 0x0)
                {
                    this.SeedArray[k] += 0x7fffffff;
                }
            }
        }
        this.inext = 0x0;
        this.inextp = 0x15;
        Seed = 0x1;
    }

    public virtual int Next()
    {
        return (int)(this.Sample() * 2147483647.0);
    }

    public virtual int Next(int maxValue)
    {
        if (maxValue < 0x0)
        {
            throw new ArgumentOutOfRangeException("maxValue");
        }
        return (int)(this.Sample() * maxValue);
    }

    public virtual int Next(int minValue, int maxValue)
    {
        if (minValue > maxValue)
        {
            throw new ArgumentOutOfRangeException("minValue");
        }
        int num = maxValue - minValue;
        if (num < 0x0)
        {
            long num2 = maxValue - minValue;
            return (((int)((long)(this.Sample() * num2))) + minValue);
        }
        return (((int)(this.Sample() * num)) + minValue);
    }

    public virtual void NextBytes(byte[] buffer)
    {
        if (buffer == null)
        {
            throw new ArgumentNullException("buffer");
        }
        for (int i = 0x0; i < buffer.Length; i++)
        {
            buffer[i] = (byte)(this.Sample() * 256.0);
        }
    }

    public virtual double NextDouble()
    {
        return this.Sample();
    }

    protected virtual double Sample()
    {
        int inext = this.inext;
        int inextp = this.inextp;
        if (++inext >= 0x38)
        {
            inext = 0x1;
        }
        if (++inextp >= 0x38)
        {
            inextp = 0x1;
        }
        int num = this.SeedArray[inext] - this.SeedArray[inextp];
        if (num < 0x0)
        {
            num += 0x7fffffff;
        }
        this.SeedArray[inext] = num;
        this.inext = inext;
        this.inextp = inextp;
        return (num * 4.6566128752457969E-10);
    }
}

经过测试，可以提供所需的输出.

Tested and it gives the desired output.

这篇关于.NET' s Random()的实现更改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！