blocks|key|1052829|text|Random+class用于创建随机数。(当然是伪随机的。)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1052830|示例：|1052831|Random+rnd+=+new+Random();
int+month++=+rnd.Next(1,+13);++//+creates+a+number+between+1+and+12
int+dice+++=+rnd.Next(1,+7);+++//+creates+a+number+between+1+and+6
int+card+++=+rnd.Next(52);+++++//+creates+a+number+between+0+and+51|code-block|syntax|javascript|1052832|如果要创建多个随机数，则应该保留Random实例并重用它。如果您创建的新实例在时间上太接近，它们将生成与随机生成器从系统时钟中播种的相同随机数序列。|1052833|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.random^0|0|6|0|C|0|0|0|0|G|6|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|6|7|12|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|13|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

The <a href="https://docs.microsoft.com/en-us/dotnet/api/system.random" rel="noreferrer"><code>Random</code> class</a> is used to create random numbers. (Pseudo-random that is of course.).

Example:

<pre class="lang-cs prettyprint-override"><code>Random rnd = new Random();
int month = rnd.Next(1, 13); // creates a number between 1 and 12
int dice = rnd.Next(1, 7); // creates a number between 1 and 6
int card = rnd.Next(52); // creates a number between 0 and 51
</code></pre>

If you are going to create more than one random number, you should keep the <code>Random</code> instance and reuse it. If you create new instances too close in time, they will produce the same series of random numbers as the random generator is seeded from the system clock.

blocks|key|1052887|text|每次执行new+Random()时，都会对其进行初始化。这意味着在一个紧凑的循环中，你会多次得到相同的值。您应该保留单个Random实例，并在同一实例上继续使用Next。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1052888|//Function+to+get+random+number
private+static+readonly+Random+getrandom+=+new+Random();

public+static+int+GetRandomNumber(int+min,+int+max)
{
++++lock(getrandom)+//+synchronize
++++{
++++++++return+getrandom.Next(min,+max);
++++}
}|code-block|syntax|javascript|1052889|entityMap^0|4|C|1O|6|28|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

Every time you do <code>new Random()</code> it is initialized. This means that in a tight loop you get the same value lots of times. You should keep a single <code>Random</code> instance and keep using <code>Next</code> on the same instance.
<pre><code>//Function to get random number
private static readonly Random getrandom = new Random();

public static int GetRandomNumber(int min, int max)
{
 lock(getrandom) // synchronize
 {
 return getrandom.Next(min, max);
 }
}
</code></pre>

blocks|key|1267398|text|Random+r+=+new+Random();
int+n+=+r.Next();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1267399|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>Random r = new Random();
int n = r.Next();
</code></pre>

blocks|key|1053275|text|我想添加一个加密的安全版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1053276|RNGCryptoServiceProvider类(MSDN|offset|length|1053277|它实现了IDisposable。|1053278|using+(RNGCryptoServiceProvider+rng+=+new+RNGCryptoServiceProvider())
{
+++byte[]+randomNumber+=+new+byte[4];//4+for+int32
+++rng.GetBytes(randomNumber);
+++int+value+=+BitConverter.ToInt32(randomNumber,+0);
}|code-block|syntax|javascript|1053279|entityMap|0|LINK|mutability|MUTABLE|url|https://msdn.microsoft.com/en-us/library/system.security.cryptography.rngcryptoserviceprovider(v=vs.110%2529.aspx)%2520or%2520[dotnetperls](http://www.dotnetperls.com/rngcryptoserviceprovider)^0|0|Q|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@$D|W|E|X|1|Y]]|A|$]]|$1|F|3|G|5|6|7|Z|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|10|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

I wanted to add a cryptographically secure version: 

RNGCryptoServiceProvider Class (<a href="https://msdn.microsoft.com/en-us/library/system.security.cryptography.rngcryptoserviceprovider(v=vs.110).aspx">MSDN</a> or <a href="http://www.dotnetperls.com/rngcryptoserviceprovider">dotnetperls</a>)

It implements IDisposable.

<pre><code>using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
{
 byte[] randomNumber = new byte[4];//4 for int32
 rng.GetBytes(randomNumber);
 int value = BitConverter.ToInt32(randomNumber, 0);
}
</code></pre>

blocks|key|1267911|text|创建随机对象|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1267912|Random+rand+=+new+Random();|code-block|syntax|javascript|1267913|并使用它|1267914|int+randomNumber+=+rand.Next(min,+max);|1267915|您不必每次需要一个随机数时都初始化new+Random()，初始化一个随机数，然后在循环或其他任何地方根据需要多次使用它|offset|length|style|CODE|1267916|entityMap^0|0|0|0|0|H|C|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@$M|X|N|Y|O|P]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

create a Random object

<pre><code>Random rand = new Random();
</code></pre>

and use it

<pre><code>int randomNumber = rand.Next(min, max);
</code></pre>

you don't have to initialize <code>new Random()</code> every time you need a random number, initiate one Random then use it as many times as you need inside a loop or whatever

blocks|key|1052869|text|您可以在Jon+Skeet为伪随机数构建的MiscUtil类库中使用Jon+Skeet的StaticRandom方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1052870|using+MiscUtil;
...

for+(int+i+=+0;+i+<+100;+
++++Console.WriteLine(StaticRandom.Next());|code-block|syntax|javascript|1052871|entityMap|0|LINK|mutability|MUTABLE|url|https://jonskeet.uk/csharp/miscutil/^0|18|C|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

You could use Jon Skeet's <a href="https://jonskeet.uk/csharp/miscutil/" rel="nofollow noreferrer">StaticRandom</a> method inside the MiscUtil class library that he built for a pseudo-random number. 

<pre><code>using MiscUtil;
...

for (int i = 0; i &lt; 100; 
 Console.WriteLine(StaticRandom.Next());
</code></pre>

blocks|key|1052944|text|修改了来自here的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1052945|如果您可以使用兼容英特尔安全密钥的中央处理器，则可以使用以下库生成真正的随机数和字符串：https://github.com/JebteK/RdRand和https://www.rdrand.com/|1052946|只需从here下载最新版本，包含Jebtek.RdRand并为其添加一条using语句。然后，你需要做的就是：|1052947|//+Check+to+see+if+this+is+a+compatible+CPU
bool+isAvailable+=+RdRandom.GeneratorAvailable();

//+Generate+10+random+characters
string+key+++++++=+RdRandom.GenerateKey(10);

+//+Generate+64+random+characters,+useful+for+API+keys+
string+apiKey++++=+RdRandom.GenerateAPIKey();

//+Generate+an+array+of+10+random+bytes
byte[]+b+++++++++=+RdRandom.GenerateBytes(10);

//+Generate+a+random+unsigned+int
uint+i+++++++++++=+RdRandom.GenerateUnsignedInt();|code-block|syntax|javascript|1052948|如果您没有兼容的CPU来执行代码，那么只需使用rdrand.com上的RESTful服务。有了你的项目中包含的RdRandom包装器库，你只需要这样做(当你注册时，你会得到1000个免费的调用)：|1052949|string+ret+=+Randomizer.GenerateKey(<length>,+"<key>");
uint+ret+++=+Randomizer.GenerateUInt("<key>");
byte[]+ret+=+Randomizer.GenerateBytes(<length>,+"<key>");|1052950|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1122483/random-string-generator-returning-same-string/22801467#22801467|1|https://github.com/JebteK/RdRand|2|https://www.rdrand.com/|3|https://github.com/JebteK/RdRand/tree/master/Versions^0|5|4|0|0|18|W|1|25|N|2|0|3|4|3|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|D|3|E|5|6|7|18|8|@]|9|@$A|19|B|1A|1|1B]|$A|1C|B|1D|1|1E]]|C|$]]|$1|F|3|G|5|6|7|1F|8|@]|9|@$A|1G|B|1H|1|1I]]|C|$]]|$1|H|3|I|5|J|7|1J|8|@]|9|@]|C|$K|L]]|$1|M|3|N|5|6|7|1K|8|@]|9|@]|C|$]]|$1|O|3|P|5|J|7|1L|8|@]|9|@]|C|$K|L]]|$1|Q|3|-4|5|6|7|1M|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]|Y|$5|T|U|V|C|$W|Z]]|10|$5|T|U|V|C|$W|11]]|12|$5|T|U|V|C|$W|13]]]]

Modified answer from <a href="https://stackoverflow.com/questions/1122483/random-string-generator-returning-same-string/22801467#22801467">here</a>.

If you have access to an Intel Secure Key compatible CPU, you can generate real random numbers and strings using these libraries: <a href="https://github.com/JebteK/RdRand" rel="noreferrer">https://github.com/JebteK/RdRand</a> and <a href="https://www.rdrand.com/" rel="noreferrer">https://www.rdrand.com/</a>

Just download the latest version from <a href="https://github.com/JebteK/RdRand/tree/master/Versions" rel="noreferrer">here</a>, include Jebtek.RdRand and add a using statement for it. Then, all you need to do is this:

<pre><code>// Check to see if this is a compatible CPU
bool isAvailable = RdRandom.GeneratorAvailable();

// Generate 10 random characters
string key = RdRandom.GenerateKey(10);

 // Generate 64 random characters, useful for API keys 
string apiKey = RdRandom.GenerateAPIKey();

// Generate an array of 10 random bytes
byte[] b = RdRandom.GenerateBytes(10);

// Generate a random unsigned int
uint i = RdRandom.GenerateUnsignedInt();
</code></pre>

If you don't have a compatible CPU to execute the code on, just use the RESTful services at rdrand.com. With the RdRandom wrapper library included in your project, you would just need to do this (you get 1000 free calls when you signup):

<pre><code>string ret = Randomizer.GenerateKey(&lt;length&gt;, "&lt;key&gt;");
uint ret = Randomizer.GenerateUInt("&lt;key&gt;");
byte[] ret = Randomizer.GenerateBytes(&lt;length&gt;, "&lt;key&gt;");
</code></pre>

blocks|key|1267865|text|我使用下面的代码来获得一个随机数(不推荐)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1267866|var+random+=+new+Random((int)DateTime.Now.Ticks);
var+randomValue+=+random.Next(startValue,+endValue+%2B+1);|code-block|syntax|javascript|1267867|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I used below code to have a random number (not recommended):

<pre><code>var random = new Random((int)DateTime.Now.Ticks);
var randomValue = random.Next(startValue, endValue + 1);
</code></pre>

blocks|key|1268360|text|只是作为将来参考的笔记。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1268361|如果你使用的是.NET核心，多个随机实例就不会像以前那样危险了。我知道这个问题来自2010年，但由于这个问题很老，但有一些吸引力，我认为记录下这个变化是一件好事。|1268362|你可以参考我之前提出的这个问题：|1268363|Did+Microsoft+change+Random+default+seed?|offset|length|1268364|基本上，他们已经将默认种子从Environment.TickCount更改为Guid.NewGuid().GetHashCode()，所以如果您创建两个随机实例，它将不会显示相同的数字。|style|CODE|1268365|您可以在此处看到与.NET框架/.NET核心(2.0.0%2B)不同的文件：https://github.com/dotnet/coreclr/pull/2192/commits/9f6a0b675e5ac0065a268554de49162c539ff66d|1268366|它不像RNGCryptoServiceProvider那样安全，但至少不会给你带来奇怪的结果。|1268367|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/57905143/did-microsoft-change-random-default-seed|1|https://github.com/dotnet/coreclr/pull/2192/commits/9f6a0b675e5ac0065a268554de49162c539ff66d^0|0|0|0|0|15|0|0|E|L|12|S|0|10|2K|1|0|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|12|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|13|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|14|8|@]|9|@$H|15|I|16|1|17]]|A|$]]|$1|J|3|K|5|6|7|18|8|@$H|19|I|1A|L|M]|$H|1B|I|1C|L|M]]|9|@]|A|$]]|$1|N|3|O|5|6|7|1D|8|@]|9|@$H|1E|I|1F|1|1G]]|A|$]]|$1|P|3|Q|5|6|7|1H|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|S|$T|$5|U|V|W|A|$X|Y]]|Z|$5|U|V|W|A|$X|10]]]]

Just as a note for future reference.

If you're using .NET Core, multiple Random instances isn't as dangerous as before. I'm aware that this question is from 2010, but since this question is old but has some attraction, I think it's a good thing to document the change.

You may refer to this question I made a while back:

<a href="https://stackoverflow.com/questions/57905143/did-microsoft-change-random-default-seed">Did Microsoft change Random default seed?</a>

Basically, they have changed the default seed from <code>Environment.TickCount</code> to <code>Guid.NewGuid().GetHashCode()</code>, so if you create 2 instances of Random it won't display the same numbers.

You can see the file diffs from .NET Framework/.NET Core (2.0.0+) here: <a href="https://github.com/dotnet/coreclr/pull/2192/commits/9f6a0b675e5ac0065a268554de49162c539ff66d" rel="noreferrer">https://github.com/dotnet/coreclr/pull/2192/commits/9f6a0b675e5ac0065a268554de49162c539ff66d</a>

It isn't as safe as RNGCryptoServiceProvider, but at least it won't give you weird results.

blocks|key|1267748|text|虽然这是可以的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1267749|Random+random+=+new+Random();
int+randomNumber+=+random.Next()|code-block|syntax|javascript|1267750|在大多数情况下，您可能希望控制限制(最小和最大数量)。因此，您需要指定随机数的开始和结束位置。|1267751|Next()方法接受两个参数:+min和max。|offset|length|style|CODE|1267752|因此，如果我希望我的随机数介于5和15之间，我会直接这样做|1267753|int+randomNumber+=+random.Next(5,+16)|1267754|entityMap^0|0|0|0|0|6|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

While this is okay:

<pre><code>Random random = new Random();
int randomNumber = random.Next()
</code></pre>

You'd want to control the limit (min and max mumbers) most of the time. So you need to specify where the random number starts and ends.

The <code>Next()</code> method accepts two parameters, min and max.

So if i want my random number to be between say 5 and 15, I'd just do

<pre><code>int randomNumber = random.Next(5, 16)
</code></pre>

blocks|key|1267818|text|这是我使用的类。工作方式类似于RandomNumber.GenerateRandom(1,+666)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1267819|internal+static+class+RandomNumber
{
++++private+static+Random+r+=+new+Random();
++++private+static+object+l+=+new+object();
++++private+static+Random+globalRandom+=+new+Random();
++++[ThreadStatic]
++++private+static+Random+localRandom;
++++public+static+int+GenerateNewRandom(int+min,+int+max)
++++{
++++++++return+new+Random().Next(min,+max);
++++}
++++public+static+int+GenerateLockedRandom(int+min,+int+max)
++++{
++++++++int+result;
++++++++lock+(RandomNumber.l)
++++++++{
++++++++++++result+=+RandomNumber.r.Next(min,+max);
++++++++}
++++++++return+result;
++++}
++++public+static+int+GenerateRandom(int+min,+int+max)
++++{
++++++++Random+random+=+RandomNumber.localRandom;
++++++++if+(random+==+null)
++++++++{
++++++++++++int+seed;
++++++++++++lock+(RandomNumber.globalRandom)
++++++++++++{
++++++++++++++++seed+=+RandomNumber.globalRandom.Next();
++++++++++++}
++++++++++++random+=+(RandomNumber.localRandom+=+new+Random(seed));
++++++++}
++++++++return+random.Next(min,+max);
++++}
}|code-block|syntax|javascript|1267820|entityMap^0|F|Z|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

This is the class I use. Works like <code>RandomNumber.GenerateRandom(1, 666)</code>

<pre><code>internal static class RandomNumber
{
 private static Random r = new Random();
 private static object l = new object();
 private static Random globalRandom = new Random();
 [ThreadStatic]
 private static Random localRandom;
 public static int GenerateNewRandom(int min, int max)
 {
 return new Random().Next(min, max);
 }
 public static int GenerateLockedRandom(int min, int max)
 {
 int result;
 lock (RandomNumber.l)
 {
 result = RandomNumber.r.Next(min, max);
 }
 return result;
 }
 public static int GenerateRandom(int min, int max)
 {
 Random random = RandomNumber.localRandom;
 if (random == null)
 {
 int seed;
 lock (RandomNumber.globalRandom)
 {
 seed = RandomNumber.globalRandom.Next();
 }
 random = (RandomNumber.localRandom = new Random(seed));
 }
 return random.Next(min, max);
 }
}
</code></pre>

blocks|key|1053433|text|Random+random+=+new+Random+();
int+randomNumber+=+random.Next+(lowerBound,upperBound);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1053434|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>Random random = new Random ();
int randomNumber = random.Next (lowerBound,upperBound);
</code></pre>

blocks|key|1268273|text|对于强随机种子，我总是使用CryptoRNG而不是Time。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1268274|using+System;
using+System.Security.Cryptography;

public+class+Program
{
++++public+static+void+Main()
++++{
++++++++var+random+=+new+Random(GetSeed());
++++++++Console.WriteLine(random.Next());
++++}

++++public+static+int+GetSeed()+
++++{
++++++++using+(var+rng+=+new+RNGCryptoServiceProvider())
++++++++{
++++++++++++var+intBytes+=+new+byte[4];
++++++++++++rng.GetBytes(intBytes);
++++++++++++return+BitConverter.ToInt32(intBytes,+0);
++++++++}
++++}
}|code-block|syntax|javascript|1268275|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

For strong random seed I always use CryptoRNG and not Time.

<pre><code>using System;
using System.Security.Cryptography;

public class Program
{
 public static void Main()
 {
 var random = new Random(GetSeed());
 Console.WriteLine(random.Next());
 }

 public static int GetSeed() 
 {
 using (var rng = new RNGCryptoServiceProvider())
 {
 var intBytes = new byte[4];
 rng.GetBytes(intBytes);
 return BitConverter.ToInt32(intBytes, 0);
 }
 }
}
</code></pre>

blocks|key|1053014|text|Random+rand+=+new+Random();
int+name+=+rand.Next()|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1053015|在第二个括号中放入您想要的任何值，确保您已经通过编写prop和double+Tab键设置了一个名称来生成代码|unstyled|1053016|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>Random rand = new Random();
int name = rand.Next()
</code></pre>

Put whatever values you want in the second parentheses
make sure you have set a name by writing prop and double tab to generate the code

blocks|key|1268039|text|根据定义，计算机通过确定性过程计算的数字不能是随机的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1268040|如果你想要一个真正的随机数，随机性来自大气噪声或放射性衰变。|1268041|您可以尝试例如RANDOM.ORG+(它会降低性能)|1268042|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

Numbers calculated by a computer through a deterministic process, cannot, by definition, be random.

If you want a genuine random numbers, the randomness comes from atmospheric noise or radioactive decay.

You can try for example RANDOM.ORG (it reduces performance)

blocks|key|1053703|text|如果您希望CSRNG生成介于最小值和最大值之间的随机数，这是为您准备的。它将使用安全的随机种子初始化Random类。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1053704|++++class+SecureRandom+:+Random
++++{
++++++++public+static+byte[]+GetBytes(ulong+length)
++++++++{
++++++++++++RNGCryptoServiceProvider+RNG+=+new+RNGCryptoServiceProvider();
++++++++++++byte[]+bytes+=+new+byte[length];
++++++++++++RNG.GetBytes(bytes);
++++++++++++RNG.Dispose();
++++++++++++return+bytes;
++++++++}
++++++++public+SecureRandom()+:+base(BitConverter.ToInt32(GetBytes(4),+0))
++++++++{

++++++++}
++++++++public+int+GetRandomInt(int+min,+int+max)
++++++++{
++++++++++++int+treashold+=+max+-+min;
++++++++++++if(treashold+!=+Math.Abs(treashold))
++++++++++++{
++++++++++++++++throw+new+ArithmeticException("The+minimum+value+can't+exceed+the+maximum+value!");
++++++++++++}
++++++++++++if+(treashold+==+0)
++++++++++++{
++++++++++++++++throw+new+ArithmeticException("The+minimum+value+can't+be+the+same+as+the+maximum+value!");
++++++++++++}
++++++++++++return+min+%2B+(Next()+%25+treashold);
++++++++}
++++++++public+static+int+GetRandomIntStatic(int+min,+int+max)
++++++++{
++++++++++++int+treashold+=+max+-+min;
++++++++++++if+(treashold+!=+Math.Abs(treashold))
++++++++++++{
++++++++++++++++throw+new+ArithmeticException("The+minimum+value+can't+exceed+the+maximum+value!");
++++++++++++}
++++++++++++if(treashold+==+0)
++++++++++++{
++++++++++++++++throw+new+ArithmeticException("The+minimum+value+can't+be+the+same+as+the+maximum+value!");
++++++++++++}
++++++++++++return+min+%2B+(BitConverter.ToInt32(GetBytes(4),+0)+%25+treashold);
++++++++}
++++}|code-block|syntax|javascript|1053705|entityMap^0|1E|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

If you want a CSRNG to generate random numbers between a min and max, this is for you. It will initialize <code>Random</code> classes with secure random seeds.

<pre class="lang-cs prettyprint-override"><code> class SecureRandom : Random
 {
 public static byte[] GetBytes(ulong length)
 {
 RNGCryptoServiceProvider RNG = new RNGCryptoServiceProvider();
 byte[] bytes = new byte[length];
 RNG.GetBytes(bytes);
 RNG.Dispose();
 return bytes;
 }
 public SecureRandom() : base(BitConverter.ToInt32(GetBytes(4), 0))
 {

 }
 public int GetRandomInt(int min, int max)
 {
 int treashold = max - min;
 if(treashold != Math.Abs(treashold))
 {
 throw new ArithmeticException("The minimum value can't exceed the maximum value!");
 }
 if (treashold == 0)
 {
 throw new ArithmeticException("The minimum value can't be the same as the maximum value!");
 }
 return min + (Next() % treashold);
 }
 public static int GetRandomIntStatic(int min, int max)
 {
 int treashold = max - min;
 if (treashold != Math.Abs(treashold))
 {
 throw new ArithmeticException("The minimum value can't exceed the maximum value!");
 }
 if(treashold == 0)
 {
 throw new ArithmeticException("The minimum value can't be the same as the maximum value!");
 }
 return min + (BitConverter.ToInt32(GetBytes(4), 0) % treashold);
 }
 }
</code></pre>

blocks|key|1053833|text|正如在其他答案中所描述的，一个很好的安全方法是使用安全的密码生成器。这里的所有示例都显示了RNGCryptoServiceProvider的用法，与我建议的解决方案相比，它编写的代码很长。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1053834|使用RandomNumberGenerator，它是在密码学API之上编写的，与RNGCryptoServiceProvider一样安全，并且具有相同的随机性。|1053835|//+Gives+a+random+number+for+the+integer+range.
//+You+can+simply+update+the+parameters+as+your+needs.
RandomNumberGenerator.GetInt32(int.MinValue,+int.MaxValue);|code-block|syntax|javascript|1053836|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.randomnumbergenerator?view=net-6.0^0|19|O|0|14|O|2|L|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@$9|10|A|11|1|12]]|E|$]]|$1|H|3|I|5|J|7|13|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

As described in other answers, a good secured approach would be to use a secure cryptographic generator. All examples here show the usage of <code>RNGCryptoServiceProvider</code> which is writing a long code compared to the solution I suggest.
Use <a href="https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.randomnumbergenerator?view=net-6.0" rel="nofollow noreferrer">RandomNumberGenerator</a> which is written on top of cryptography API’s. It is as secure as <code>RNGCryptoServiceProvider</code> and same randomness.
<pre><code>// Gives a random number for the integer range.
// You can simply update the parameters as your needs.
RandomNumberGenerator.GetInt32(int.MinValue, int.MaxValue);
</code></pre>

blocks|key|1053749|text|有许多实用函数或服务可以采用与System.Random相同的方式进行更好的缓存，因此它适合于通用实现：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1053750|static+public+class+CachedService<T>+where+T+:+new()+{
++++static+public+T+Get+{+get;+}+=+new+T();
}|code-block|syntax|javascript|1053751|用于随机(或类似)：|1053752|CachedService<System.Random>.Get.Next(999);|1053753|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

There are a number utility functions or services that are better cached in the same way that System.Random should be, so it lends itself to a generic implementation:
<pre><code>static public class CachedService&lt;T&gt; where T : new() {
 static public T Get { get; } = new T();
}
</code></pre>
To use for random (or similar):
<pre><code>CachedService&lt;System.Random&gt;.Get.Next(999);
</code></pre>

blocks|key|1053495|text|我假设你想要一个均匀分布的随机数生成器，如下所示。在包括C#和C%2B%2B在内的大多数编程语言中，随机数在使用前都没有正确地进行混洗。这意味着你会一次又一次地得到相同的数字，这并不是真正随机的。为了避免一遍又一遍地绘制相同的数字，您需要一个种子。通常情况下，时间节拍对于这个任务来说是可以的。请记住，如果您每次都使用相同的种子，您将一次又一次地获得相同的数字。因此，请始终尝试使用可变种子。时间是种子的好来源，因为它们总是在变化。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1053496|int+GetRandomNumber(int+min,+int+max)
{
++++Random+rand+=+new+Random((int)DateTime.Now.Ticks);
++++return+rand.Next(min,+max);
}|code-block|syntax|javascript|1053497|如果您正在寻找用于正态分布的随机数生成器，则可以使用Box-Muller变换。检查随机高斯变量问题中yoyoyoyosef的答案。因为你想要整型，所以你必须在最后将双精度值转换为整型。|1053498|Random+rand+=+new+Random();+//reuse+this+if+you+are+generating+many
double+u1+=+1.0-rand.NextDouble();+//uniform(0,1]+random+doubles
double+u2+=+1.0-rand.NextDouble();
double+randStdNormal+=+Math.Sqrt(-2.0+*+Math.Log(u1))+*
+++++++++Math.Sin(2.0+*+Math.PI+*+u2);+//random+normal(0,1)
double+randNormal+=
+++++++++mean+%2B+stdDev+*+randStdNormal;+//random+normal(mean,stdDev%5E2)|1053499|Random+Gaussian+Variables|offset|length|1053500|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/218060/random-gaussian-variables^0|0|0|0|0|0|P|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@]|9|@$M|11|N|12|1|13]]|A|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

I will assume that you want a uniformly distributed random number generator like below. Random number in most of programming language including C# and C++ is not properly shuffled before using them. This means that you will get the same number over and over, which isn't really random. To avoid to draw the same number over and over, you need a seed. Typically, ticks in time is ok for this task. Remember that you will get the same number over and over if you are using the same seed every time. So try to use varying seed always. Time is a good source for seed because they chage always.

<pre><code>int GetRandomNumber(int min, int max)
{
 Random rand = new Random((int)DateTime.Now.Ticks);
 return rand.Next(min, max);
}
</code></pre>

if you are looking for random number generator for normal distribution, you might use a Box-Muller transformation. Check the answer by yoyoyoyosef in Random Gaussian Variable Question. Since you want integer, you have to cast double value to integer at the end. 

<pre><code>Random rand = new Random(); //reuse this if you are generating many
double u1 = 1.0-rand.NextDouble(); //uniform(0,1] random doubles
double u2 = 1.0-rand.NextDouble();
double randStdNormal = Math.Sqrt(-2.0 * Math.Log(u1)) *
 Math.Sin(2.0 * Math.PI * u2); //random normal(0,1)
double randNormal =
 mean + stdDev * randStdNormal; //random normal(mean,stdDev^2)
</code></pre>

<a href="https://stackoverflow.com/questions/218060/random-gaussian-variables">Random Gaussian Variables</a>

blocks|key|1268578|text|Random+r=new+Random();
int+Numbers=r.next(min+value,+max+value);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1268579|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>Random r=new Random();
int Numbers=r.next(min value, max value);
</code></pre>

blocks|key|1268056|text|为什么不使用int+randomNumber+=+Random.Range(start_range,+end_range)？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1268057|entityMap^0|6|1J|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Why not use <code>int randomNumber = Random.Range(start_range, end_range)</code> ?

blocks|key|1053531|text|我总是有生成随机数的方法，这对各种目的都有帮助。我希望这也能对你有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1053532|public+class+RandomGenerator++
{++
++++public+int+RandomNumber(int+min,+int+max)++
++++{++
++++++++var+random+=+new+Random();++
++++++++return+random.Next(min,+max);++
++++}++

++++public+string+RandomString(int+size,+bool+lowerCase)++
++++{++
++++++++var+builder+=+new+StringBuilder();++
++++++++var+random++=+new+Random();++
++++++++char+ch;++

++++++++for+(int+i+=+0;+i+<+size;+i%2B%2B)++
++++++++{++
++++++++++++ch+=+Convert.ToChar(Convert.ToInt32(Math.Floor(26+*+random.NextDouble()+%2B+65)));++
++++++++++++builder.Append(ch);++
++++++++}++

++++++++if+(lowerCase)++
++++++++++++return+builder.ToString().ToLower();++
++++++++return+builder.ToString();++
++++}++
}|code-block|syntax|javascript|1053533|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I always have methods that generate random numbers which help for various purposes. I hope this may help you too:

<pre><code>public class RandomGenerator 
{ 
 public int RandomNumber(int min, int max) 
 { 
 var random = new Random(); 
 return random.Next(min, max); 
 } 

 public string RandomString(int size, bool lowerCase) 
 { 
 var builder = new StringBuilder(); 
 var random = new Random(); 
 char ch; 

 for (int i = 0; i &lt; size; i++) 
 { 
 ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65))); 
 builder.Append(ch); 
 } 

 if (lowerCase) 
 return builder.ToString().ToLower(); 
 return builder.ToString(); 
 } 
}
</code></pre>

blocks|key|1268300|text|重复使用Random的一个实例|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1268301|//+Somewhat+better+code...
Random+rng+=+new+Random();
for+(int+i+=+0;+i+<+100;+i%2B%2B)
{
++++Console.WriteLine(GenerateDigit(rng));
}
...
static+int+GenerateDigit(Random+rng)
{
++++//+Assume+there'd+be+more+logic+here+really
++++return+rng.Next(10);
}|code-block|syntax|javascript|1268302|本文将介绍随机性为什么会导致如此多的问题，以及如何解决这些问题。http://csharpindepth.com/Articles/Chapter12/Random.aspx|offset|length|1268303|entityMap|0|LINK|mutability|MUTABLE|url|http://csharpindepth.com/Articles/Chapter12/Random.aspx^0|0|0|W|1J|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Use one instance of Random repeatedly

<pre><code>// Somewhat better code...
Random rng = new Random();
for (int i = 0; i &lt; 100; i++)
{
 Console.WriteLine(GenerateDigit(rng));
}
...
static int GenerateDigit(Random rng)
{
 // Assume there'd be more logic here really
 return rng.Next(10);
}
</code></pre>

This article takes a look at why randomness causes so many problems, and how to address them.
<a href="http://csharpindepth.com/Articles/Chapter12/Random.aspx" rel="nofollow noreferrer">http://csharpindepth.com/Articles/Chapter12/Random.aspx</a>

blocks|key|1053462|text|快速方便的内联，使用下面的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1053463|new+Random().Next(min,+max);

//+for+example+unique+name
strName+%2B=+"_"+%2B+new+Random().Next(100,+999);|code-block|syntax|javascript|1053464|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Quick and easy for inline, use bellow code:

<pre><code>new Random().Next(min, max);

// for example unique name
strName += "_" + new Random().Next(100, 999);
</code></pre>

blocks|key|1268109|text|+int+n+=+new+Random().Next();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1268110|您还可以为Next()函数指定最小值和最大值。像这样：|unstyled|offset|length|style|CODE|1268111|+int+n+=+new+Random().Next(5,+10);|1268112|entityMap^0|0|5|6|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|P|8|@$G|Q|H|R|I|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|M|3|-4|5|F|7|T|8|@]|9|@]|A|$]]]|N|$]]

<pre><code> int n = new Random().Next();
</code></pre>

You can also give minimum and maximum value to <code>Next()</code> function. Like:

<pre><code> int n = new Random().Next(5, 10);
</code></pre>

How do I generate a random integer in C#?

问如何生成一个随机整型数？
EN

回答 25

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问如何生成一个随机整型数？EN

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问如何生成一个随机整型数？
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