根据字符串生成对应Hash值
时间:2022-07-23
本文章向大家介绍根据字符串生成对应Hash值,主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项,具有一定的参考价值,需要的朋友可以参考一下。
目录
- 根据字符串生成Hash值 唯一ID值
- 一丶Hash函数
- 1.APHash
- 2.RsHash
- 3.jsHash
- 4.PJW Hash
- 5.ELF Hash
- 6.BKDR Hash
- 7.SDMB Hash
- 8.DJB Hash
- 9.DEKHash
- 二丶代码下载
- 一丶Hash函数
根据字符串生成Hash值 唯一ID值
参考网址: http://www.partow.net/programming/hashfunctions/
一丶Hash函数
1.APHash
APHash
uint32_t hash(const char* message, size_t message_length)
{
uint32_t internal_state = 0xA5A5A5A5; // IV: A magic number
uint32_t message_block = 0;
// Loop over the message 32-bits at-a-time
while (message_length >= 4)
{
memcpy(message_block, message, sizeof(uint32_t));
internal_state = mix(message_block, internal_state);
message_length -= sizeof(uint32_t);
message += sizeof(uint32_t);
}
// Are there any remaining bytes?
if (message_length)
{
memcpy(message_block, message, message_length);
internal_state = mix(message_block, internal_state);
}
return internal_state;
}
另一种
// AP Hash Function
unsigned int APHash(char *str)
{
unsigned int hash = 0;
int i;
for (i=0; *str; i++)
{
if ((i & 1) == 0)
{
hash ^= ((hash << 7) ^ (*str++) ^ (hash >> 3));
}
else
{
hash ^= (~((hash << 11) ^ (*str++) ^ (hash >> 5)));
}
}
return (hash & 0x7FFFFFFF);
}
2.RsHash
unsigned int RSHash(const char* str, unsigned int length)
{
unsigned int b = 378551;
unsigned int a = 63689;
unsigned int hash = 0;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = hash * a + (*str);
a = a * b;
}
return hash;
}
3.jsHash
unsigned int JSHash(const char* str, unsigned int length)
{
unsigned int hash = 1315423911;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash ^= ((hash << 5) + (*str) + (hash >> 2));
}
return hash;
}
4.PJW Hash
nsigned int PJWHash(const char* str, unsigned int length)
{
const unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8);
const unsigned int ThreeQuarters = (unsigned int)((BitsInUnsignedInt * 3) / 4);
const unsigned int OneEighth = (unsigned int)(BitsInUnsignedInt / 8);
const unsigned int HighBits =
(unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);
unsigned int hash = 0;
unsigned int test = 0;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = (hash << OneEighth) + (*str);
if ((test = hash & HighBits) != 0)
{
hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));
}
}
return hash;
}
5.ELF Hash
unsigned int ELFHash(const char* str, unsigned int length)
{
unsigned int hash = 0;
unsigned int x = 0;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = (hash << 4) + (*str);
if ((x = hash & 0xF0000000L) != 0)
{
hash ^= (x >> 24);
}
hash &= ~x;
}
return hash;
}
6.BKDR Hash
unsigned int BKDRHash(const char* str, unsigned int length)
{
unsigned int seed = 131; /* 31 131 1313 13131 131313 etc.. */
unsigned int hash = 0;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = (hash * seed) + (*str);
}
return hash;
}
7.SDMB Hash
unsigned int SDBMHash(const char* str, unsigned int length)
{
unsigned int hash = 0;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = (*str) + (hash << 6) + (hash << 16) - hash;
}
return hash;
}
8.DJB Hash
unsigned int DJBHash(const char* str, unsigned int length)
{
unsigned int hash = 5381;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = ((hash << 5) + hash) + (*str);
}
return hash;
}
9.DEKHash
unsigned int DEKHash(const char* str, unsigned int length)
{
unsigned int hash = len;
unsigned int i = 0;
for (i = 0; i < length; ++str, ++i)
{
hash = ((hash << 5) ^ (hash >> 27)) ^ (*str);
}
return hash;
}
二丶代码下载
链接:https://pan.baidu.com/s/1gXE4O7y2dJmCoGO6AuandQ 提取码:1111
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