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Asked: 2026-05-10T15:55:26+00:00

Like many of you, I use ReSharper to speed up the development process. When

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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?
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  1. 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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