C语言中哈希表怎么实现C语言开放寻址法的代码示例

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define TABLE_SIZE 10

typedef struct {
    char *key;
    char *value;
} HashItem;

typedef struct {
    HashItem **items;
    int size;
    int count;
} HashTable;

// 哈希函数 (简单示例)
unsigned long hash(char *str) {
    unsigned long hash = 5381;
    int c;

    while ((c = *str++))
        hash = ((hash << 5) + hash) + c; /* hash * 33 + c */

    return hash % TABLE_SIZE;
}

// 创建哈希表
HashTable *create_table(int size) {
    HashTable *table = (HashTable*) malloc(sizeof(HashTable));
    table->size = size;
    table->count = 0;
    table->items = (HashItem**) calloc(table->size, sizeof(HashItem*));
    return table;
}

// 插入元素
void ht_insert(HashTable *table, char *key, char *value) {
    int index = hash(key);
    HashItem *item = (HashItem*) malloc(sizeof(HashItem));
    item->key = strdup(key); // 复制字符串
    item->value = strdup(value);

    // 线性探测解决冲突
    while (table->items[index] != NULL) {
        index = (index + 1) % table->size; // 循环探测
    }

    table->items[index] = item;
    table->count++;
}

// 查找元素
char *ht_search(HashTable *table, char *key) {
    int index = hash(key);

    while (table->items[index] != NULL) {
        if (strcmp(table->items[index]->key, key) == 0) {
            return table->items[index]->value;
        }
        index = (index + 1) % table->size;
    }

    return NULL; // 未找到
}

// 打印哈希表
void ht_print(HashTable *table) {
    for (int i = 0; i < table->size; i++) {
        if (table->items[i] != NULL) {
            printf("Index: %d, Key: %s, Value: %s\n", i, table->items[i]->key, table->items[i]->value);
        }
    }
}

// 释放哈希表内存
void ht_free(HashTable *table) {
    for (int i = 0; i < table->size; i++) {
        if (table->items[i] != NULL) {
            free(table->items[i]->key);
            free(table->items[i]->value);
            free(table->items[i]);
        }
    }
    free(table->items);
    free(table);
}


int main() {
    HashTable *ht = create_table(TABLE_SIZE);

    ht_insert(ht, "name", "Alice");
    ht_insert(ht, "age", "30");
    ht_insert(ht, "city", "New York");

    printf("Value for key 'name': %s\n", ht_search(ht, "name"));
    printf("Value for key 'age': %s\n", ht_search(ht, "age"));
    printf("Value for key 'city': %s\n", ht_search(ht, "city"));
    printf("Value for key 'country': %s\n", ht_search(ht, "country")); // 不存在的key

    ht_print(ht);

    ht_free(ht);

    return 0;
}