得到一个重复值的概率对字符串调用GetHash code（）的时候 [英] Probability of getting a duplicate value when calling GetHashCode() on strings

问题描述

我想知道什么是调用GetHash code（）的字符串实例方法时得到重复值的概率。例如，根据：

I want to know what is the probability of getting duplicate values when calling the GetHashCode() method on string instances. For instance, according to:

<一个href=\"http://ashishkhandelwal.arkutil.com/index.php/csharp/gethash$c$c-method-hash$c$c-and-hashtable-behavior-deep-level/\">http://ashishkhandelwal.arkutil.com/index.php/csharp/gethash$c$c-method-hash$c$c-and-hashtable-behavior-deep-level/

雅和brainlessness具有相同的哈希code：175803953（x86计算机上）

"blair" and "brainlessness" has the same Hash Code: 175803953 (on an x86 machine).

感谢。

推荐答案

大。

（对不起乔恩！）

越来越短串中的散列碰撞的概率的非常大的。鉴于从常用词抽取一组只有10000不同的短字符串的，那里是在该组至少一个冲突的概率约为1％。如果你有八万串，还有是至少一种冲突的概率为50％以上。

The probability of getting a hash collision among short strings is extremely large. Given a set of only ten thousand distinct short strings drawn from common words, the probability of there being at least one collision in the set is approximately 1%. If you have eighty thousand strings, the probability of there being at least one collision is over 50%.

有关显示设置的大小和碰撞概率之间的关系的曲线图，看到我对这个问题的文章：

For a graph showing the relationship between set size and probability of collision, see my article on the subject:

<一个href=\"http://blogs.msdn.com/b/ericlippert/archive/2010/03/22/socks-birthdays-and-hash-collisions.aspx\">http://blogs.msdn.com/b/ericlippert/archive/2010/03/22/socks-birthdays-and-hash-collisions.aspx

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