C#中字符串的快速散列函数 [英] A fast hash function for string in C#

问题描述

我想对长度不超过 30 的字符串进行哈希处理.如果我关心时间，那么最好的做法是什么.该函数将被调用超过 1 亿次.目前我正在使用以下代码，

I want to hash a string of length up-to 30. What will be the best idea to do that if time is my concern. The function will be called over 100 million times. currently I am using the following code,

static UInt64 CalculateHash(string read, bool lowTolerance)
{
    UInt64 hashedValue = 0;
    int i = 0;
    while (i < read.Length)
    {
        hashedValue += read.ElementAt(i) * (UInt64)Math.Pow(31, i);
        if (lowTolerance) i += 2;
        else i++;
    }
    return hashedValue;
}

推荐答案

static UInt64 CalculateHash(string read)
{
    UInt64 hashedValue = 3074457345618258791ul;
    for(int i=0; i<read.Length; i++)
    {
        hashedValue += read[i];
        hashedValue *= 3074457345618258799ul;
    }
    return hashedValue;
}

这是一个 Knuth 哈希.您也可以使用 Jenkins.

This is a Knuth hash. You can also use Jenkins.

这篇关于C#中字符串的快速散列函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！