c语言实现hashtable

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

#define SIZE 10

typedef struct hash_table_item_s {
    int key;
    int value;
    struct hash_table_item_s* next;
} hash_table_item;

hash_table_item* hash_table[SIZE];

int hash_function(int key) {
    return key % SIZE;
}

void hash_table_insert(int key, int value) {
    int index = hash_function(key);
    hash_table_item* item = malloc(sizeof(hash_table_item));
    item->key = key;
    item->value = value;
    item->next = hash_table[index];
    hash_table[index] = item;
}

hash_table_item* hash_table_search(int key) {
    int index = hash_function(key);
    hash_table_item* item = hash_table[index];
    while (item) {
        if (item->key == key) {
            return item;
        }
        item = item->next;
    }
    return NULL;
}

void hash_table_delete(int key) {
    int index = hash_function(key);
    hash_table_item* item = hash_table[index];
    hash_table_item* prev = NULL;
    while (item) {
        if (item->key == key) {
            if (prev) {
                prev->next = item->next;
            } else {
                hash_table[index] = item->next;
            }
            free(item);
            return;
        }
        prev = item;
        item = item->next;
    }
}

int main() {
    hash_table_insert(1, 10);
    hash_table_insert(2, 20);
    hash_table_insert(3, 30);
    hash_table_item* item = hash_table_search(2);
    if (item) {
        printf("key: %d, value: %d\n", item->key, item->value);
    }
    hash_table_delete(2);
    item = hash_table_search(2);
    if (item) {
        printf("key: %d, value: %d\n", item->key, item->value);
    } else {
        printf("key not found\n");
    }
    return 0;
}
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