若干经典的字符串哈希函数

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原创最新推荐文章于 2026-06-01 11:05:20 发布 607 阅读 AI 写同款· GEO 优化 ›

暴雪公司关于字符串匹配的hash算法暴雪公司有个经典的字符串的hash公式先提一个简单的问题，假如有一个庞大的字符串数组，然后给你一个单独的字符串，让你从这个数组中查找是否有这个字符串并找到它，你会怎么做？有一个方法最简单，老老实实从头查到尾，一个一个比较，直到找到为止，我想只要学过程序设计的人都能把这样一个程序作出来，但要是有程序员把这样的程序交给用户，我只能用无语来评价，或许它真的能工作，但...也只能如此了。阅读详情

// RS Hash Function
unsigned int RSHash( char   * str)
{
        unsigned int b =   378551 ;
        unsigned int a =   63689 ;
        unsigned int hash =   0 ;

         while ( * str)
          {
                hash = hash * a + ( * str ++ );
                a *= b;
        }

         return (hash &   0x7FFFFFFF );
}

// JS Hash Function
unsigned int JSHash( char   * str)
{
        unsigned int hash =   1315423911 ;

         while ( * str)
          {
                hash ^= ((hash <<   5 ) + ( * str ++ ) + (hash >>   2 ));
        }

         return (hash &   0x7FFFFFFF );
}

// P. J. Weinberger Hash Function
unsigned int PJWHash( char   * str)
{
        unsigned int BitsInUnignedInt = (unsigned int )( sizeof (unsigned int ) *
8 );
        unsigned int ThreeQuarters     = (unsigned int )((BitsInUnignedInt   *   3 )
/   4 );
        unsigned int OneEighth         = (unsigned int )(BitsInUnignedInt /   8 );

        unsigned int HighBits          = (unsigned int )( 0xFFFFFFFF ) << (BitsInU
nignedInt - OneEighth);
        unsigned int hash              =   0 ;
        unsigned int test              =   0 ;

         while ( * str)
          {
                hash = (hash << OneEighth) + ( * str ++ );
                 if ((test = hash & HighBits) !=   0 )
                  {
                        hash = ((hash ^ (test >> ThreeQuarters)) & ( ~ HighBits)
);
                }
        }

         return (hash &   0x7FFFFFFF );
}

// ELF Hash Function
unsigned int ELFHash( char   * str)
{
        unsigned int hash =   0 ;
        unsigned int x     =   0 ;

         while ( * str)
          {
                hash = (hash <<   4 ) + ( * str ++ );
                 if ((x = hash &   0xF0000000L ) !=   0 )
                  {
                        hash ^= (x >>   24 );
                        hash &=   ~ x;
                }
        }

         return (hash &   0x7FFFFFFF );
}

// BKDR Hash Function
unsigned int BKDRHash( char   * str)
{
        unsigned int seed =   131 ; // 31 131 1313 13131 131313 etc..
         unsigned int hash =   0 ;

         while ( * str)
          {
                hash = hash * seed + ( * str ++ );
        }

         return (hash &   0x7FFFFFFF );
}

// SDBM Hash Function
unsigned int SDBMHash( char   * str)
{
        unsigned int hash =   0 ;

         while ( * str)
          {
                hash = ( * str ++ ) + (hash <<   6 ) + (hash <<   16 ) - hash;
        }

         return (hash &   0x7FFFFFFF );
}

// DJB Hash Function
unsigned int DJBHash( char   * str)
{
        unsigned int hash =   5381 ;

         while ( * str)
          {
                hash += (hash <<   5 ) + ( * str ++ );
        }

         return (hash &   0x7FFFFFFF );
}

// 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 );
}
比较经典的字符串hash就这些了吧,"ELF Hash Function" <-这个比较常用..

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