更新时间:2023-11-28 17:24:52
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?
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.