为什么'397'用于ReSharper GetHashCode覆盖？ [英] Why is '397' used for ReSharper GetHashCode override?

问题描述

像许多人一样，我使用ReSharper来加速开发过程。当您使用它来覆盖类的相等成员时，它为GetHashCode（）生成的代码生成如下所示：

$ b

  public override int GetHashCode（）
 {
 unchecked 
 {
 int result =（Key！= null？Key.GetHashCode（）：0）; 
 result =（result * 397）^（EditableProperty！= null？EditableProperty.GetHashCode（）：0）; 
 result =（result * 397）^ ObjectId; 
返回结果; 
} 
} 
  

当然，我有一些我自己的成员，但我想知道的是为什么397？

• 编辑：所以我的问题会更好措辞，有什么'特殊'关于397以外的素数是质数？

解决方案

可能是因为397是足够大的主要元素，可以使结果变量溢出并混合散列的位，从而提供更好的散列代码分布。 397和其他同等数量的素数不同，没有什么特别的。

Like many of you, I use ReSharper to speed up the development process. When you use it to override the equality members of a class, the code-gen it produces for GetHashCode() looks like:

    public override int GetHashCode()
    {
        unchecked
        {
            int result = (Key != null ? Key.GetHashCode() : 0);
            result = (result * 397) ^ (EditableProperty != null ? EditableProperty.GetHashCode() : 0);
            result = (result * 397) ^ ObjectId;
            return result;
        }
    }

Of course I have some of my own members in there, but what I am wanting to know is why 397?

• EDIT: So my question would be better worded as, is there something 'special' about the 397 prime number outside of it being a prime number?

解决方案

Probably because 397 is a prime of sufficient size to cause the result variable to overflow and mix the bits of the hash somewhat, providing a better distribution of hash codes. There's nothing particularly special about 397 that distinguishes it from other primes of the same magnitude.

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