什么整数散列函数是好的，接受一个整数哈希键？

Knuth的乘方法：

Knuth's multiplicative method:

hash(i)=i*2654435761 mod 2^32

在一般情况下，你应该选择一个乘数是（在本例 2 ^ 32 ）的散列大小的顺序，也没有共同的因素吧。这样，散列函数涵盖了所有你的散列空间均匀。

In general, you should pick a multiplier that is in the order of your hash size (2^32 in the example) and has no common factors with it. This way the hash function covers all your hash space uniformly.

编辑：此散列函数的最大缺点是它preserves整除，所以如果你的整数都整除2或4（这是不常见），他们的哈希值也将如此。这是哈希表的问题 - 你可以结束了只有1/2或桶的1/4正在使用

The biggest disadvantage of this hash function is that it preserves divisibility, so if your integers are all divisible by 2 or by 4 (which is not uncommon), their hashes will be too. This is a problem in hash tables - you can end up with only 1/2 or 1/4 of the buckets being used.