链式哈希表的实现

哈希算法一般用于快速查找和加密算法

chtbl.h

#ifndef CHTBL_H#define CHTBL_H#include <stdlib.h>#include "list.h"/* Define a structure for chained hash tables. */typedef struct CHTbl_ {int                buckets;int                (*h)(const void *key);int                (*match)(const void *key1, const void *key2);void               (*destroy)(void *data);int                size;List               *table;} CHTbl;/* Public Interface. */int chtbl_init(CHTbl *htbl, int buckets, int (*h)(const void *key), int   (*match)(const void *key1, const void *key2), void (*destroy)(void *data));void chtbl_destroy(CHTbl *htbl);int chtbl_insert(CHTbl *htbl, const void *data);int chtbl_remove(CHTbl *htbl, void **data);int chtbl_lookup(const CHTbl *htbl, void **data);#define chtbl_size(htbl) ((htbl)->size)#endif

chtbl.m

#include <stdlib.h>#include <string.h>#include "list.h"#include "chtbl.h"/* chtbl_init */int chtbl_init(CHTbl *htbl, int buckets, int (*h)(const void *key), int   (*match)(const void *key1, const void *key2), void (*destroy)(void*data)) {int                i;/*Allocate space for the hash table.*/if ((htbl->table = (List *)malloc(buckets * sizeof(List))) == NULL)   return -1;/*Initialize the buckets.*/htbl->buckets = buckets;for (i = 0; i < htbl->buckets; i++)   list_init(&htbl->table[i], destroy);/*Encapsulate the functions.*/htbl->h = h;htbl->match = match;htbl->destroy = destroy;/*Initialize the number of elements in the table.*/htbl->size = 0;return 0;}/* chtbl_destroy */void chtbl_destroy(CHTbl *htbl) {int                i;/*Destroy each bucket.*/for (i = 0; i < htbl->buckets; i++) {   list_destroy(&htbl->table[i]);}/*Free the storage allocated for the hash table.*/free(htbl->table);/*No operations are allowed now, but clear the structure as a precaution.*/memset(htbl, 0, sizeof(CHTbl));return;}/* chtbl_insert */int chtbl_insert(CHTbl *htbl, const void *data) {void               *temp;int                bucket,                   retval;/* Do nothing if the data is already in the table. */temp = (void *)data;if (chtbl_lookup(htbl, &temp) == 0)   return 1;/* Hash the key. */bucket = htbl->h(data) % htbl->buckets;/*Insert the data into the bucket.*/if ((retval = list_ins_next(&htbl->table[bucket], NULL, data)) == 0)   htbl->size++;return retval;}/* chtbl_remove */int chtbl_remove(CHTbl *htbl, void **data) {ListElmt           *element,                   *prev;int                bucket;/*Hash the key.*/bucket = htbl->h(*data) % htbl->buckets;/*Search for the data in the bucket.*/prev = NULL;for (element = list_head(&htbl->table[bucket]); element != NULL; element =   list_next(element)) {   if (htbl->match(*data, list_data(element))) {      /*Remove the data from the bucket.*/      if (list_rem_next(&htbl->table[bucket], prev, data) == 0) {         htbl->size--;         return 0;         }      else {         return -1;      }   }   prev = element;}/*Return that the data was not found.*/return -1;}/* chtbl_lookup */int chtbl_lookup(const CHTbl *htbl, void **data) {ListElmt           *element;int                bucket;/*Hash the key.*/bucket = htbl->h(*data) % htbl->buckets;/*Search for the data in the bucket.*/for (element = list_head(&htbl->table[bucket]); element != NULL; element =   list_next(element)) {   if (htbl->match(*data, list_data(element))) {      /*Pass back the data from the table.*/      *data = list_data(element);      return 0;   }}/*Return that the data was not found.*/return -1;}