HashTable

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <time.h>/*=================hash table start=========================================*/#define HASH_TABLE_MAX_SIZE 10000typedef struct HashNode_Struct HashNode;struct HashNode_Struct{char* sKey;int nValue;HashNode* pNext;};HashNode* hashTable[HASH_TABLE_MAX_SIZE]; //hash table data strcutrueint hash_table_size;  //the number of key-value pairs in the hash table!//initialize hash tablevoid hash_table_init(){hash_table_size = 0;memset(hashTable, 0, sizeof(HashNode*) * HASH_TABLE_MAX_SIZE);}//string hash functionunsigned int hash_table_hash_str(const char* skey){const signed char *p = (const signed char*)skey;unsigned int h = *p;if(h){for(p += 1; *p != '\0'; ++p)h = (h << 5) - h + *p;}return h;}//insert key-value into hash tablevoid hash_table_insert(const char* skey, int nvalue){if(hash_table_size >= HASH_TABLE_MAX_SIZE){printf("out of hash table memory!\n");return;}unsigned int pos = hash_table_hash_str(skey) % HASH_TABLE_MAX_SIZE;HashNode* pHead =  hashTable[pos];while(pHead){if(strcmp(pHead->sKey, skey) == 0){printf("%s already exists!\n", skey);return ;}pHead = pHead->pNext;}HashNode* pNewNode = (HashNode*)malloc(sizeof(HashNode));memset(pNewNode, 0, sizeof(HashNode));pNewNode->sKey = (char*)malloc(sizeof(char) * (strlen(skey) + 1));strcpy(pNewNode->sKey, skey);pNewNode->nValue = nvalue;pNewNode->pNext = hashTable[pos];hashTable[pos] = pNewNode;hash_table_size++;}//remove key-value frome the hash tablevoid hash_table_remove(const char* skey){unsigned int pos = hash_table_hash_str(skey) % HASH_TABLE_MAX_SIZE;if(hashTable[pos]){HashNode* pHead = hashTable[pos];HashNode* pLast = NULL;HashNode* pRemove = NULL;while(pHead){if(strcmp(skey, pHead->sKey) == 0){pRemove = pHead;break;}pLast = pHead;pHead = pHead->pNext;}if(pRemove){if(pLast)pLast->pNext = pRemove->pNext;elsehashTable[pos] = NULL;free(pRemove->sKey);free(pRemove);}}}//lookup a key in the hash tableHashNode* hash_table_lookup(const char* skey){unsigned int pos = hash_table_hash_str(skey) % HASH_TABLE_MAX_SIZE;if(hashTable[pos]){HashNode* pHead = hashTable[pos];while(pHead){if(strcmp(skey, pHead->sKey) == 0)return pHead;pHead = pHead->pNext;}}return NULL;}//print the content in the hash tablevoid hash_table_print(){printf("===========content of hash table=================\n");int i;for(i = 0; i < HASH_TABLE_MAX_SIZE; ++i)if(hashTable[i]){HashNode* pHead = hashTable[i];printf("%d=>", i);while(pHead){printf("%s:%d  ", pHead->sKey, pHead->nValue);pHead = pHead->pNext;}printf("\n");}}//free the memory of the hash tablevoid hash_table_release(){int i;for(i = 0; i < HASH_TABLE_MAX_SIZE; ++i){if(hashTable[i]){HashNode* pHead = hashTable[i];while(pHead){HashNode* pTemp = pHead;pHead = pHead->pNext;if(pTemp){free(pTemp->sKey);free(pTemp);}}}}}/* ===============================hash table end=========================*//* ============================test function ============================*/#define MAX_STR_LEN 20#define MIN_STR_LEN 10void rand_str(char r[]){int i;int len = MIN_STR_LEN + rand() % (MAX_STR_LEN - MIN_STR_LEN);for(i = 0; i < len - 1; ++i)r[i] = 'a' + rand() % ( 'z' - 'a');r[len - 1] = '\0';}int main(int argc, char** argv){srand(time(NULL));hash_table_init();printf("insert testing.........\n");int n = 10;const char *key1 = "aaammd";const char *key2 = "xzzyym";const char *key3 = "cdcded";hash_table_insert(key1, 110);hash_table_insert(key2, 220);hash_table_insert(key3, 330);char str[MAX_STR_LEN + 1];while(n--){rand_str(str);hash_table_insert(str, n);}hash_table_print();printf("\nlookup testing..........\n");HashNode* pNode = hash_table_lookup(key1);printf("lookup result:%d\n", pNode->nValue);pNode = hash_table_lookup(key2);printf("lookup result:%d\n", pNode->nValue);printf("\nremove testing..........\n");printf("before remove %s:\n", key3);hash_table_print();hash_table_remove(key3);printf("after remove:\n");hash_table_print();hash_table_release();system("pause");return 0;}