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      常用Hash算法(C语言的简单实现)
      发布时间:2016-12-21 08:03:56 关键词: 常用hash算法
      内容简介:下面小编就为大家带来一篇常用Hash算法(C语言的简单实现)。小编觉得挺不错的,现在就分享给大家,也给大家做个参考。一起跟随小编过来看看吧

    如下所示:

    #include "GeneralHashFunctions.h" 
     
    unsigned int RSHash(char* str, unsigned int len) 
    { 
      unsigned int b  = 378551; 
      unsigned int a  = 63689; 
      unsigned int hash = 0; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash = hash * a + (*str); 
       a  = a * b; 
      } 
     
      return hash; 
    } 
    /* End Of RS Hash Function */ 
     
     
    unsigned int JSHash(char* str, unsigned int len) 
    { 
      unsigned int hash = 1315423911; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash ^= ((hash << 5) + (*str) + (hash >> 2)); 
      } 
     
      return hash; 
    } 
    /* End Of JS Hash Function */ 
     
     
    unsigned int PJWHash(char* str, unsigned int len) 
    { 
      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 < len; str++, i++) 
      { 
       hash = (hash << OneEighth) + (*str); 
     
       if((test = hash & HighBits) != 0) 
       { 
         hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits)); 
       } 
      } 
     
      return hash; 
    } 
    /* End Of P. J. Weinberger Hash Function */ 
     
     
    unsigned int ELFHash(char* str, unsigned int len) 
    { 
      unsigned int hash = 0; 
      unsigned int x  = 0; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash = (hash << 4) + (*str); 
       if((x = hash & 0xF0000000L) != 0) 
       { 
         hash ^= (x >> 24); 
       } 
       hash &= ~x; 
      } 
     
      return hash; 
    } 
    /* End Of ELF Hash Function */ 
     
     
    unsigned int BKDRHash(char* str, unsigned int len) 
    { 
      unsigned int seed = 131; /* 31 131 1313 13131 131313 etc.. */ 
      unsigned int hash = 0; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash = (hash * seed) + (*str); 
      } 
     
      return hash; 
    } 
    /* End Of BKDR Hash Function */ 
     
     
    unsigned int SDBMHash(char* str, unsigned int len) 
    { 
      unsigned int hash = 0; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash = (*str) + (hash << 6) + (hash << 16) - hash; 
      } 
     
      return hash; 
    } 
    /* End Of SDBM Hash Function */ 
     
     
    unsigned int DJBHash(char* str, unsigned int len) 
    { 
      unsigned int hash = 5381; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash = ((hash << 5) + hash) + (*str); 
      } 
     
      return hash; 
    } 
    /* End Of DJB Hash Function */ 
     
     
    unsigned int DEKHash(char* str, unsigned int len) 
    { 
      unsigned int hash = len; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash = ((hash << 5) ^ (hash >> 27)) ^ (*str); 
      } 
      return hash; 
    } 
    /* End Of DEK Hash Function */ 
     
     
    unsigned int BPHash(char* str, unsigned int len) 
    { 
      unsigned int hash = 0; 
      unsigned int i  = 0; 
      for(i = 0; i < len; str++, i++) 
      { 
       hash = hash << 7 ^ (*str); 
      } 
     
      return hash; 
    } 
    /* End Of BP Hash Function */ 
     
     
    unsigned int FNVHash(char* str, unsigned int len) 
    { 
      const unsigned int fnv_prime = 0x811C9DC5; 
      unsigned int hash   = 0; 
      unsigned int i     = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash *= fnv_prime; 
       hash ^= (*str); 
      } 
     
      return hash; 
    } 
    /* End Of FNV Hash Function */ 
     
     
    unsigned int APHash(char* str, unsigned int len) 
    { 
      unsigned int hash = 0xAAAAAAAA; 
      unsigned int i  = 0; 
     
      for(i = 0; i < len; str++, i++) 
      { 
       hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ (*str) * (hash >> 3)) : 
                    (~((hash << 11) + ((*str) ^ (hash >> 5)))); 
      } 
     
      return hash; 
    } 
    /* End Of AP Hash Function */ 

    以上就是小编为大家带来的常用Hash算法(C语言的简单实现)的全部内容了,希望对大家有所帮助,多多支持乐码库~

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