C语言UThash基本操作

UTHash在数据管理中应用广泛，现给出使用范例以供参考：

#include <uthash.h> // 包含头文件

//1、hash
typedef struct myhash {
    int key;
    int cnt;
    UT_hash_handle hh;
} MyHash;
MyHash *g_myHash = NULL;
// 查找、插入
void HashFind(int key)
{
    MyHash *temp = NULL;
    HASH_FIND_INT(g_myHash, &key, temp);
    if (temp == NULL) {
        temp = (MyHash *)malloc(sizeof(MyHash));
        temp->key = key;
        temp->cnt = 1;
        HASH_ADD_INT(g_myHash, key, temp);
    } else {
        temp->cnt++;
    }
}
// 遍历
void HashFor()
{
    MyHash *newTemp = NULL;
    MyHash *temp = NULL;
    HASH_ITER(hh, g_myHash, newTemp, temp) {
        printf("%d %d,", newTemp->key, newTemp->cnt);
    }

    for (MyHash *p = g_myHash; p != NULL; p = (MyHash *)p->hh.next) { // 向后遍历

    }
    for (MyHash *p = g_myHash; p != NULL; p = (MyHash *)p->hh.prev) { // 向前遍历

    }
}

void HashFree()
{
    MyHash *newTemp = NULL;
    MyHash *temp = NULL;
    HASH_ITER(hh, g_myHash, newTemp, temp) {
        HASH_DEL(g_myHash, newTemp);
        free(newTemp);
        newTemp = NULL;
    }
}

typedef struct {
    int a;
    int b;
} KeyStr;
typedef struct {
    KeyStr key; // key是结构体
    UT_hash_handle hh;
} HashStr;
int findPairs(int* nums, int numsSize, int k)
{
    HashStr *hashTbl = NULL;
    int ret = 0;
    for (int i = 0; i < numsSize - 1; i++) {
        for (int j = i + 1; j < numsSize; j++) {
            if (abs(nums[j] - nums[i]) != k) {
                continue;
            }
            HashStr *temp = NULL;
            KeyStr key;
            memset(&key, 0, sizeof(KeyStr));
            key.a = nums[i];
            key.b = nums[j];
            HASH_FIND(hh, hashTbl, &key, sizeof(KeyStr), temp);
            if (temp) {
                continue;
            }
            temp = (HashStr *)malloc(sizeof(HashStr));
            temp->key.a = key.a;
            temp->key.b = key.b;
            HASH_ADD(hh, hashTbl, key, sizeof(KeyStr), temp);
            if (nums[i] == nums[j]) {
                ret++;
                continue;
            }
            KeyStr key1;
            memset(&key1, 0, sizeof(KeyStr));
            key1.a = nums[j];
            key1.b = nums[i];
            HashStr *p = NULL;
            HASH_FIND(hh, hashTbl, &key1, sizeof(KeyStr), p);
            if (p == NULL) {
                p = (HashStr *)malloc(sizeof(HashStr));
                p->key.a = key1.a;
                p->key.b = key1.b;
                HASH_ADD(hh, hashTbl, key, sizeof(KeyStr), p);
                ret++;
            }
        }
    }
    HashStr *q1 = NULL, *q2 = NULL;
    HASH_ITER(hh, hashTbl, q1, q2) {
        printf("%d %d\n", q1->key.a, q1->key.b);
    }
    return ret;
}
int CompCnt(MyHash *a, MyHash *b)
{
    return a->cnt - b->cnt; // 升序排列
}
// 排序
void HashSort()
{
    HASH_SORT(g_myHash, CompCnt);
}
// 获取hash表中元素个数
int HashGetCnt()
{
    int cnt = HASH_COUNT(g_myHash);
    return cnt;
}