使用C语言写一个hash表

好的，以下是一个简单的C语言实现的hash表：

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

#define TABLE_SIZE 100

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

typedef struct {
    HashNode** nodes;
} HashTable;

unsigned int hash(const char* key) {
    unsigned int hash = 0;
    for (int i = 0; i < strlen(key); i++) {
        hash = hash * 31 + key[i];
    }
    return hash;
}

HashTable* createHashTable() {
    HashTable* table = malloc(sizeof(HashTable));
    table->nodes = calloc(TABLE_SIZE, sizeof(HashNode*));
    return table;
}

void set(HashTable* table, const char* key, const char* value) {
    unsigned int index = hash(key) % TABLE_SIZE;
    HashNode* node = table->nodes[index];
    while (node != NULL && strcmp(node->key, key) != 0) {
        node = node->next;
    }
    if (node == NULL) {
        node = malloc(sizeof(HashNode));
        node->key = strdup(key);
        node->next = table->nodes[index];
        table->nodes[index] = node;
    }
    node->value = strdup(value);
}

char* get(HashTable* table, const char* key) {
    unsigned int index = hash(key) % TABLE_SIZE;
    HashNode* node = table->nodes[index];
    while (node != NULL && strcmp(node->key, key) != 0) {
        node = node->next;
    }
    if (node == NULL) {
        return NULL;
    } else {
        return node->value;
    }
}

int main() {
    HashTable* table = createHashTable();
    set(table, "apple", "red");
    set(table, "banana", "yellow");
    set(table, "grape", "purple");
    printf("apple is %s\n", get(table, "apple"));
    printf("banana is %s\n", get(table, "banana"));
    printf("grape is %s\n", get(table, "grape"));
    return 0;
}

这个hash表使用了链表来解决hash冲突的问题，每个节点包含一个键和一个值。使用`set`函数可以向hash表中添加一个键值对，使用`get`函数可以根据键获取对应的值。