字符串__哈希算法

 // 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 );

}

    原文作者:哈希算法
    原文地址: https://blog.csdn.net/nocml/article/details/6693994
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