www.pudn.com > calc5.zip > htab.cpp

//------------------------------------ 
//  htab.cpp 
//  (c) Bartosz Milewski, 1994 
//------------------------------------ 
 
#include "htab.h" 
 
#include  
#include  
 
// Find the list in hash table that may contain 
// the id of the string we are looking for 
 
List const & HTable::Find (char const * str) const 
{ 
    int i = hash (str); 
    assert (i >= 0 && i < _size); 
    return _aList [i]; 
} 
 
void HTable::Add (char const * str, int id) 
{ 
    int i = hash (str); 
    assert (i >= 0 && i < _size); 
    _aList [i].Add (id); 
} 
 
// Private hashing function 
 
int HTable::hash (char const * str) const 
{ 
    // must be unsigned, hash should return positive number 
    unsigned h = str [0]; 
	assert (h != 0); // no empty strings, please 
    for (int i = 1; str [i] != 0; ++i) 
        h = (h << 4) + str [i]; 
    return h % _size;  // small positive integer 
}