随机相遇不那么随机 [英] Random encounter not so random

问题描述

你好，我在用 C# 生成随机数时遇到了一些问题现在我有了这个功能.

public Color getRandomColor(){Color1 = new Random().Next(new Random().Next(0, 100), new Random().Next(200, 255));Color2 = new Random().Next(new Random().Next(0, 100), new Random().Next(200, 255));Color3 = new Random().Next(new Random().Next(0, 100), new Random().Next(200, 255));颜色颜色 = Color.FromArgb(Color1, Color2, Color3);Console.WriteLine("R:" + Color1 + " G: " + Color2 + " B: " + Color3 + " = " + color.Name);返回颜色；}

现在你可能会注意到那里有很多 new Random()，那是因为我想排除它可能是同一个实例错误的可能性.

我现在运行这个函数 8 次，几次.现在是输出.

R: 65 G: 65 B: 65 = ff414141R:242 G:242 B:242 = fff2f2f2R:205 G:205 B:205 = ffcdcdcdR:40 G:40 B:40 = ff282828R:249 G:249 B:249 = fff9f9f9R:249 G:249 B:249 = fff9f9f9R:94 G:94 B:94 = ff5e5e5eR:186 G:186 B:186 = ffbababaR:142 G:142 B:142 = ff8e8e8eR:190 G:190 B:190 = ffbebebeR:19 G:19 B:19 = ff131313R:119 G:119 B:119 = ff777777R:119 G:119 B:119 = ff777777R:75 G:75 B:75 = ff4b4b4bR:169 G:169 B:169 = ffa9a9a9R:127 G:127 B:127 = ff7f7f7fR:73 G:73 B:73 = ff494949R:27 G:27 B:27 = ff1b1b1bR:125 G:125 B:125 = ff7d7d7dR:212 G:212 B:212 = ffd4d4d4R:174 G:174 B:174 = 植物科R:0 G:0 B:0 = ff000000R:0 G:0 B:0 = ff000000R:220 G:220 B:220 = ffdcdcdc

正如你所看到的，这又不是那么随机了，但为什么会发生这种情况呢?我该如何反击?

解决方案

您正在为您需要的每个单个值创建一个新的 Random.

尝试创建一个唯一的 Random 对象并多次调用 .Next() 函数.

public Color getRandomColor(){随机 rand = new Random();Color1 = rand.Next(rand.Next(0, 100), rand.Next(200, 255));Color2 = rand.Next(rand.Next(0, 100), rand.Next(200, 255));Color3 = rand.Next(rand.Next(0, 100), rand.Next(200, 255));颜色颜色 = Color.FromArgb(Color1, Color2, Color3);Console.WriteLine("R:" + Color1 + " G: " + Color2 + " B: " + Color3 + " = " + color.Name);返回颜色；}

取自 关于随机对象的 MSDN 文档:><块引用>

默认情况下，Random类的无参数构造函数使用系统时钟来生成它的种子值，而它的参数化构造函数可以根据当前时间的滴答数取一个Int32值.然而，因为时钟的分辨率是有限的，所以使用无参数构造函数以紧密连续的方式创建不同的 Random 对象会创建产生相同随机数序列的随机数生成器

Hello i am having some problems generating random numbers with C# Now i have this function.

public Color getRandomColor()
{
    Color1 = new Random().Next(new Random().Next(0, 100), new Random().Next(200, 255));
    Color2 = new Random().Next(new Random().Next(0, 100), new Random().Next(200, 255));
    Color3 = new Random().Next(new Random().Next(0, 100), new Random().Next(200, 255));
    Color color = Color.FromArgb(Color1, Color2, Color3);
    Console.WriteLine("R: " + Color1 + " G: " + Color2 + " B: " + Color3 + " = " + color.Name);
    return color;
}

Now you might notice that there are ALOT of new Random() there, that is because i want to weed out the probability that it could be a same instance error.

I now run this function 8 times, a couple of times. Now here are the out puts.

R: 65 G: 65 B: 65 = ff414141
R: 242 G: 242 B: 242 = fff2f2f2
R: 205 G: 205 B: 205 = ffcdcdcd
R: 40 G: 40 B: 40 = ff282828
R: 249 G: 249 B: 249 = fff9f9f9
R: 249 G: 249 B: 249 = fff9f9f9
R: 94 G: 94 B: 94 = ff5e5e5e
R: 186 G: 186 B: 186 = ffbababa

R: 142 G: 142 B: 142 = ff8e8e8e
R: 190 G: 190 B: 190 = ffbebebe
R: 19 G: 19 B: 19 = ff131313
R: 119 G: 119 B: 119 = ff777777
R: 119 G: 119 B: 119 = ff777777
R: 75 G: 75 B: 75 = ff4b4b4b
R: 169 G: 169 B: 169 = ffa9a9a9
R: 127 G: 127 B: 127 = ff7f7f7f

R: 73 G: 73 B: 73 = ff494949
R: 27 G: 27 B: 27 = ff1b1b1b
R: 125 G: 125 B: 125 = ff7d7d7d
R: 212 G: 212 B: 212 = ffd4d4d4
R: 174 G: 174 B: 174 = ffaeaeae
R: 0 G: 0 B: 0 = ff000000
R: 0 G: 0 B: 0 = ff000000
R: 220 G: 220 B: 220 = ffdcdcdc

As you can see this is not so random again, but why dose this happens? and how can i counter it?

解决方案

You're creating a new Random for each single value you need.

Try creating a unique Random object and calling the .Next() function multiple times.

public Color getRandomColor()
{
    Random rand = new Random();

    Color1 = rand.Next(rand.Next(0, 100), rand.Next(200, 255));
    Color2 = rand.Next(rand.Next(0, 100), rand.Next(200, 255));
    Color3 = rand.Next(rand.Next(0, 100), rand.Next(200, 255));
    Color color = Color.FromArgb(Color1, Color2, Color3);
    Console.WriteLine("R: " + Color1 + " G: " + Color2 + " B: " + Color3 + " = " + color.Name);
    return color;
}

Taken from MSDN documentation on Random object :

By default, the parameterless constructor of the Random class uses the system clock to generate its seed value, while its parameterized constructor can take an Int32 value based on the number of ticks in the current time. However, because the clock has finite resolution, using the parameterless constructor to create different Random objects in close succession creates random number generators that produce identical sequences of random numbers

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