uthash哈希的使用

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做项目遇到需要使用到键值对的，一般我们会优先考虑map,multimap。

最近在看cocos2d-x源码，发现了一个更高效的用法uthash

头文件uthash.h在cocos2dx\support\data_support\下可以找到

下面是一个简单的使用：

#include "uthash.h"#include <stdio.h>#include <stdlib.h>/*这个uthash必须构造一个结构体*/struct packet{int key;            /*这个是用来做hash的key值*/char msg[10]; UT_hash_handle hh; /*这个结构是uthash的结构体，里面包含next，prev，hash值等信息*/};int main(){struct packet *pkt, *tmp;int i;struct packet *hash_packet = NULL; /*必须初始化为NULL*//*打印这个hash的节点数*/printf ("hash count = %d \n", HASH_COUNT(hash_packet));/*往hash中添加节点*/for (i=0; i<10; i++){pkt = (struct packet *)malloc(sizeof(struct packet));pkt->key = i;sprintf (pkt->msg, "i=%d", i);HASH_FIND_INT(hash_packet, &i, tmp);if (tmp != NULL){printf ("The key(%d) exists in hash. \n", i);continue;}HASH_ADD_INT(hash_packet, key, pkt);printf ("insert item. key=%d,value=%p \n", i, pkt);}printf ("hash count = %d \n", HASH_COUNT(hash_packet));/*通过key查找*/for (i=0; i<13; i++){HASH_FIND_INT(hash_packet, &i, tmp);if (tmp == NULL){printf ("find not item. key=%d,value=%p \n", i, tmp);continue;}printf ("find item. key=%d,value=%p \n", i, tmp);}printf ("hash count = %d \n", HASH_COUNT(hash_packet));/*遍历这个hash表*/struct packet* mytemp = NULL;for (mytemp = hash_packet; mytemp != NULL; mytemp = (packet*)mytemp->hh.next)printf (" %d => %s \n", mytemp->key, mytemp->msg);/*删除节点*/for (i=0; i<13; i++){HASH_FIND_INT(hash_packet, &i, tmp);if (tmp == NULL){printf ("find not item. key=%d,value=%p \n", i, tmp);continue;}/*删除节点不会释放你的空间必须自己释放*/HASH_DEL(hash_packet, tmp);free(tmp);printf ("delete itme. key=%d,value=%p \n", i, tmp);}printf ("hash count = %d \n", HASH_COUNT(hash_packet));system("pause");return 0;}

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