c语言hashmap库函数

C语言本身不提供HashMap的库函数，但是可以通过自己编写代码实现HashMap。下面是一个简单的实现：

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

#define TABLE_SIZE 10000

struct Node {
    char* key;
    char* value;
    struct Node* next;
};

struct Node* table[TABLE_SIZE];

// Hash function
unsigned long hash(char* key) {
    unsigned long hash = 5381;
    int c;
    while (c = *key++) {
        hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
    }
    return hash % TABLE_SIZE;
}

// Put a key-value pair into the table
void put(char* key, char* value) {
    unsigned long index = hash(key);
    struct Node* node = table[index];
    while (node != NULL) {
        if (strcmp(node->key, key) == 0) {
            node->value = value;
            return;
        }
        node = node->next;
    }
    struct Node* new_node = malloc(sizeof(struct Node));
    new_node->key = key;
    new_node->value = value;
    new_node->next = table[index];
    table[index] = new_node;
}

// Get the value associated with a key
char* get(char* key) {
    unsigned long index = hash(key);
    struct Node* node = table[index];
    while (node != NULL) {
        if (strcmp(node->key, key) == 0) {
            return node->value;
        }
        node = node->next;
    }
    return NULL;
}

int main() {
    put("apple", "red");
    put("banana", "yellow");
    put("orange", "orange");

    printf("The color of apple is %s\n", get("apple"));
    printf("The color of banana is %s\n", get("banana"));
    printf("The color of orange is %s\n", get("orange"));

    return 0;
}

这个HashMap使用了开放地址法来处理哈希冲突，链表来保存键值对。可以通过调整`TABLE_SIZE`的大小来改变哈希表的大小。