如何生成"随机"而且还与QUOT;独特的"号码？ [英] How to generate "random" but also "unique" numbers?

问题描述

如何产生的随机数。？如何语言如Java等产生随机数，它被特别是如何为GUID的完成。？我发现，像Pseudorandomnumber生成算法使用的初始值。

但我需要创建一个随机数的程序，其中一些曾经发生绝不应该重复，即使在系统重新启动等。我想，我需要存储值的任何地方，这样我可以检查一些重复或没有，但这样的例子不胜枚举超过这个极限，将是太复杂了。

解决方案

第一：如果数字是保证绝不重复，这不是很随意

二：有很多的 PRNG算法

更新：

第三：有一个的IETF RFC的UUID （什么MS调用的GUID），但你应该认识到，（U | G）的UID的不的密码安全，如果这是你所关心

<。 p>更新2：

如果要真正地在生产中使用的代码是这样的（不只是为自己的熏陶）请使用预先存在的库。这是何许那几乎肯定会在这微妙的错误，如果你从来没有这么做过（或者即使你有）代码

更新3：

这里的文档用于.NET的GUID

How are random numbers generated.? How do languages such as java etc generate random numbers, especially how it is done for GUIDs.? i found that algorithms like Pseudorandomnumber generator uses initial values.

But i need to create a random number program, in which a number once occurred should never repeats even if the system is restarted etc. I thought that i need to store the values anywhere so that i can check if the number repeats or not, but it will be too complex when the list goes beyond limits.?

解决方案

First: If the number is guaranteed to never repeat, it's not very random.

Second: There are lots of PRNG algorithms.

UPDATE:

Third: There's an IETF RFC for UUIDs (what MS calls GUIDs), but you should recognize that (U|G)UIDs are not cryptographically secure, if that is a concern for you.

UPDATE 2:

If you want to actually use something like this in production code (not just for your own edification) please use a pre-existing library. This is the sort of code that is almost guaranteed to have subtle bugs in it if you've never done it before (or even if you have).

UPDATE 3:

Here's the docs for .NET's GUID

这篇关于如何生成&QUOT;随机&QUOT;而且还与QUOT;独特的&QUOT;号码？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！