guid | 易学教程

How are .NET 4 GUIDs generated?

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问题 I am aware of the multitude of questions here as well as Raymond\'s excellent (as usual) post. However, since the algorithm to create GUIDs was changed apparently, I found it hard to get my hands on any up-to-date information. The MSDN seems to try and provide as few information as possible. What is known about how GUIDs are generated in .NET 4? What was changed, and how does it affect the security (\"randomness\") and integrity (\"uniqueness\")? One specific aspect I\'m interested in: In v1,

How unique is the php session id

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How unique is the php session id? I got the impression from various things that I've read that I should not rely on two users never getting the same sessionid. Isn't it a GUID? Session_id can indeed be duplicated, but the probability is very low. If you have a website with a fair traffic, it may happens once in you web site life, and will just annoy one user for one session. This is not worth to care about unless you expect to build a very high traffic website or a service for the bank industry. djsadinoff It's not very unique as shipped. In the default configuration it's the result of a hash

Generating Guids in Ruby

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问题 I have problem that is really easily solved with Guids. In particular, for a password reset workflow, I would like to send a Guid token to a user\'s email and have them reset their password using the token. Since guids are unique, this is pretty secure and saves me emailing people passwords, which is risky. I noticed there is one Guid gem for Ruby; but it looks quite old, and it writes stuff to the file system. Does anyone know of any other gems that can create a globally unique identifier? I

What is a good unique PC identifier?

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问题 I\'ve been looking at the code in this tutorial, and I found that it uses My.Computer.Name to save settings that shouldn\'t roam between computers. It\'s entirely possible, however, for a user to have two identically named PCs. If they wanted to have the same username on each PC, for example, they may very well end up with two PCs named Username-PC. What are some good methods of identifying different PCs? Do PCs have GUIDs associated with them, or should I look into pulling the serial number

C# how to create a Guid value?

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问题 One field of our struct is Guid type. How to generate a valid value for it? 回答1: Guid id = Guid.NewGuid(); 回答2: Guid.NewGuid() creates a new random guid. 回答3: There are two ways var guid = Guid.NewGuid(); or var guid = Guid.NewGuid().ToString(); both use the Guid class, the first creates a Guid Object, the second a Guid string. 回答4: Guid.NewGuid() will create one 回答5: var guid = new Guid(); Hey, its a 'valid', although not very useful, Guid. (the guid is all zeros, if you don't know.

如何定义一个接口（接口Interface只在COM组件中定义了，MFC和C++都没有接口的概念）

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接口是COM中的关键词，在c++中并没有这个概念。接口是一种极度的抽象。接口用在COM组件中有自己的GUID值，因此定义接口时一定要指定它的GUID值。实际上接口就是struct，即#define interface struct 一、接口的定义步骤： 0.包含头文件：#include "afxtempl.h" 1.定义一个GUID值：static const IID IID_IFunction={guid value} 2.声明一个接口：DECLARE_INTERFACE_(IFunction,IUnknwon)，该宏表示：struct _declspec(novtable) IFunction:public IUnknown 3.写接口中定义的函数。总之就是： static const IID IID_IFunction ={guid value}; DECLARE_INTERFACE_(IFunction,IUnknown) { STEMETHOD(show)(CString str，int a) PURE;//你要定义的接口方法 } 这样一个接口就定义好了。来源： CSDN 作者： jiangqin115 链接： https://blog.csdn.net/jiangqin115/article/details/103241137

How Random is System.Guid.NewGuid()? (Take two)

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问题 Before you start marking this as a duplicate, read me out. The other question has a (most likely) incorrect accepted answer. I do not know how .NET generates its GUIDs, probably only Microsoft does, but there\'s a high chance it simply calls CoCreateGuid(). That function however is documented to be calling UuidCreate(). And the algorithms for creating an UUID are pretty well documented. Long story short, be as it may, it seems that System.Guid.NewGuid() indeed uses version 4 UUID generation

How Random is System.Guid.NewGuid()?

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问题 I know this may sounds like a pointless question, but hear me out... I basically want to know if I can trust the GUID to generate a value which will be unique 100% of the time and impossible to predict. I\'m basically rolling my on login system for a website and want to know if the GUID is secure enough for session cookies. Any background on how the GUID is generated would be much appreciated in evaluating the answers. Thanks for the links to duplicate questions, however, my question is

Is it safe to assume a GUID will always be unique?

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问题 I know there is a minute possibility of a clash but if I generated a batch of 1000 GUIDs (for example), would it be safe to assume they\'re all unique to save testing each one? Bonus question An optimal way to test a GUID for uniqueness? Bloom filter maybe? 回答1: Yes, you can. Since GUIDs are 128 bits long, there is admittedly a minute possibility of a clash—but the word "minute" is nowhere near strong enough. There are so many GUIDs that if you generate several trillion of them randomly, you

Test if string is a guid without throwing exceptions?

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问题 I want to try to convert a string to a Guid, but I don\'t want to rely on catching exceptions ( for performance reasons - exceptions are expensive for usability reasons - the debugger pops up for design reasons - the expected is not exceptional In other words the code: public static Boolean TryStrToGuid(String s, out Guid value) { try { value = new Guid(s); return true; } catch (FormatException) { value = Guid.Empty; return false; } } is not suitable. I would try using RegEx, but since the