如果输入相同的种子，Delphi 的随机生成器是否与 C# 的计算相同？

Question

当我遇到这个问题时，我正在将一些 Delphi 代码翻译成 c# 代码。我没有 Delphi 的环境设置，所以我无法自己测试。

德尔福：

RandSeed := var1;
Result := Random($FF);

c#:

Random RandSeed = new Random(var1);
Result = RandSeed.Next(255);

这些会将相同的值放入 Result 中吗？如果没有，有什么想法吗？

Answer 1

Delphi PRNG 是一个确定性的linear congruential generator，其中 134775813 为 a 和 1 为 c，并返回范围受限数字的高 32 位.这是 C# 中的一个实现，它返回与 Delphi 相同的值：

using System;

class DelphiRandom
{
    int _seed;

    public DelphiRandom(int seed)
    {
        _seed = seed;
    }

    int GetNext() // note: returns negative numbers too
    {
        _seed = _seed * 0x08088405 + 1;
        return _seed;
    }

    public int Next(int maxValue)
    {
        ulong result = (ulong) (uint) GetNext() * (ulong) (uint) maxValue;
        return (int) (result >> 32);
    }
}

class App
{
    static void Main()
    {
        DelphiRandom r = new DelphiRandom(42);
        for (int i = 0; i < 10; ++i)
            Console.WriteLine(r.Next(100));
    }
}

Answer 2

当然不是，因为它们使用不同的 RNG。您或许可以使用 Windows API 中的 RNG、创建自己的 RNG 或使用一些 RNG 库来实现这一点。

另一种确保您的 RNG 为给定种子创建相同数字的方法是编写一个 DLL 并将其用于 Delphi 和 C#。

顺便说一句，如果您想自己编写 RNG 代码，Wikipedia 是获取一些常用生成器名称的良好起点。完成后，您应该通过一些 statistical test 运行它，以确保它对您来说足够“随机”。

Answer 3

仅使用 Delphi 2009 和每个种子的前 10 个结果：

Seed:   0, result:   0,   8, 219,  51,  69, 171,  81,  41,  94, 108
Seed:   1, result:   8, 219,  51,  69, 171,  81,  41,  94, 108,  20
Seed:   2, result:  16, 176, 138,  87,  17, 246,   1, 148, 122, 188
Seed:   3, result:  24, 132, 225, 105, 119, 156, 216, 202, 135, 100
Seed:   4, result:  32,  89,  57, 123, 221,  66, 176,   0, 149,  13
Seed:   5, result:  40,  45, 145, 141,  67, 231, 136,  54, 163, 180
Seed:   6, result:  48,   2, 232, 159, 169, 141,  96, 108, 176,  92
Seed:   7, result:  56, 213,  64, 177,  16,  51,  56, 161, 190,   5
Seed:   8, result:  64, 170, 151, 195, 118, 216,  16, 215, 203, 172
Seed:   9, result:  72, 127, 238, 213, 219, 126, 231,  14, 217,  84
Seed:  10, result:  80,  83,  70, 231,  66,  36, 191,  67, 231, 252
Seed:  11, result:  88,  40, 157, 248, 168, 201, 151, 121, 244, 164
Seed:  12, result:  96, 251, 244,  11,  14, 111, 111, 175,   3,  76
Seed:  13, result: 104, 208,  76,  29, 116,  21,  71, 228,  17, 244
Seed:  14, result: 112, 164, 163,  47, 218, 186,  31,  27,  30, 156
Seed:  15, result: 120, 121, 250,  65,  64,  96, 246,  81,  44,  69
Seed:  16, result: 128,  78,  83,  83, 166,   6, 206, 134,  57, 236
Seed:  17, result: 136,  34, 170, 101,  13, 171, 166, 188,  71, 148
Seed:  18, result: 144, 246,   2, 119, 114,  81, 126, 242,  85,  61
Seed:  19, result: 152, 202,  89, 137, 216, 246,  86,  40,  98, 228
Seed:  20, result: 160, 159, 176, 155,  63, 156,  46,  94, 112, 140
Seed:  21, result: 168, 115,   8, 173, 164,  66,   6, 148, 126,  53
Seed:  22, result: 176,  72,  95, 191,  11, 231, 221, 201, 139, 220
Seed:  23, result: 184,  29, 182, 209, 113, 141, 181,   0, 153, 132
Seed:  24, result: 192, 240,  14, 227, 214,  51, 141,  54, 166,  45
Seed:  25, result: 200, 197, 101, 245,  61, 216, 101, 107, 180, 212

我看到了一个模式；-)。

Answer 4

对于 Java 开发人员

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package org.delphi;

/**
 *
 * @author ulmum
 * Using Code for C# from Barry Kelly http://stackoverflow.com/users/3712/barry-kelly
 */
class DelphiRandom {

    int _seed;

    public DelphiRandom(int seed) {
        _seed = seed;
    }

    int GetNext() // note: returns negative numbers too
    {
        _seed = _seed * 0x08088405 + 1;
        return _seed;
    }

    public int Next(int maxValue) {
        long result = (long) (int) GetNext() * (long) (int) maxValue;
        return ((int) (result >> 32) & 0xff); //Here Prevent Negative Numbers
    }
}

class App {

    public static void main(String[] args) {
        DelphiRandom r = new DelphiRandom(0);
        for (int i = 0; i < 10; ++i) {
            System.out.println(r.Next(256));
        }
    }
}