1. qsort 、bsearch
包含头文件:#include<stdlib.h>
void qsort(void *base , size_t nmemb , size_t size,
int(*comopare)(const void*elem1,const void *elem2))
void *bsearch(const void*key , const void*base , siez_t nmemb , size_t size,
int(*compare)(const void*elem1,const void*elem2))
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int compar(const void* elem1,const void* elem2)
{
//将elem1,elem2转换为指向指针的指针，再取址
return strcmp(*(char**)elem1,*(char**)elem2);
}
int main()
{
//指针数组
char *pBase[] = {"c++","php","java","perl","c","ruby","python"};
int num = 7;
int i;
char *key = "c++";
char **result;
//快速排序
qsort(pBase,num,sizeof(char*),compar);
for (i=0;i<num;i++)
{
printf("%s ",pBase[i]);
}
printf("\n");
//二分查找前必须排序
result = (char**)bsearch(&key,pBase,num,sizeof(char*),compar);
if (result==NULL)
{
printf("%s not found\n",key);
}
else
{
printf("%s was found\n",*result);
}
return 0;
}
/*
运行结果：
c c++ java perl php python ruby
c++ was found
*/
2. lsearch 、 lfind
包含头文件<stdlib.h>
void lsearch(const void*key , const void*base , size_t *nmemb , size_t *size,
int(*compare)(const void*elem1,const void*elem2))
void lfind(const void*key , const void*base , size_t *nmemb , size_t *size,
int(*compare)(const void*elem1,const void*elem2))
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int compar(const void* elem1,const void* elem2)
{
//将elem1,elem2转换为指向指针的指针，再取址
return strcmp(*(char**)elem1,*(char**)elem2);
}
int main()
{
//指针数组,由于lsearch找不到元素时，会插入该数据，所以需要数组够大
char *pBase[10] = {"c++","php","java","perl","c","ruby","python"};
int num = 7;
int i;
char *key = "c++";
char *key1 = "hello";
char **result;
for (i=0;i<num;i++)
{
printf("%s ",pBase[i]);
}
printf("\n");
//线性搜索
result = (char**)lfind(&key,pBase,&num,sizeof(char*),compar);//传入的是key的地址
if (result==NULL)
{
printf("%s not found\n",key);
}
else
{
printf("%s was found\n",*result);
}
for (i=0;i<num;i++)
{
printf("%s ",pBase[i]);
}
printf("\n");
//线性搜索
result = NULL;
result = (char**)lsearch(&key1,pBase,&num,sizeof(char*),compar);
//lsearch如果找到数据，则返回数据地址，否则返回数组base的地址，这跟其他不同
if (!strcmp(*result,"hello"))
{
printf("%s not found\n",key1);
}
else
{
printf("%s was found\n",*result);
}
//与lfind不同，lsearch会将不存在的元素插入到数组中再返回
i = 0;
while(pBase[i])
{
printf("%s ",pBase[i++]);
}
printf("\n");
return 0;
}
/*
运行结果：
c++ php java perl c ruby python
c++ was found
c++ php java perl c ruby python
hello not found
c++ php java perl c ruby python hello
*/
3. hcreate 、hdestroy 、hearch
包含头文件<search.h>
int hcreate(size_t nel);
void hdestory();
ENTRY *hsearch(ENRTY item,ACTION aciotn);
typedef struct entry
{
char *key;
char *data;
}ENTRY;
aciotn有两个值FIND和ENTER
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <search.h>
typedef struct student
{
int age;
int grade;
}stu;
int main()
{
int res = 0;
//建立一个容量为100的哈希表
res = hcreate(100);
if (NULL == res)
{
printf("can not create hashtable\n");
return 1;
}
ENTRY item;
stu s[] = { {20,100} , {25,60} , {22,80} };;
//插入一个数据(key=001,data=stu(20,100))
item.key = "001";//key
item.data = (void*)&s[0];
hsearch(item,ENTER);
item.key = "002";//key
item.data = (void*)&s[1];
hsearch(item,ENTER);
item.key = "002";//key
item.data = (void*)&s[2];
hsearch(item,ENTER);
//查找key为001的元素
ENTRY *pEntry;
item.key = "001";
pEntry = hsearch(item,FIND);
if (pEntry!=NULL)
{
printf("find student key %s : %d %d\n",pEntry->key,((stu*)pEntry->data)->age,((stu*)pEntry->data)->grade);
}
else
{
printf("can not find\n");
}
//销毁哈希表
hdestroy();
return 0;
}
/*
运行结果：
find student key 001 : 20 100
*/
4. tdelete 、tfind、tsearch、twalk
包含头文件<search.h>
void *tdelete(const void*key,void **rootp,int(*cmpar)(const void *a,const void*b))
void *tfind(const void*key,void **rootp,int(*cmpar)(const void *a,const void*b))
void *tsearch(const void*key,void **rootp,int(*cmpar)(const void *a,const void*b))
void twalk(const void*root,void(*action)(void *nodep,VISIT which,int depth))
#include<search.h>
#include<stdlib.h>
#include<stdio.h>
//比较函数
int compare(const void*a,const void*b)
{
if (*(int*)a < *(int*)b)
{
return -1;
}
else if (*(int*)a > *(int*)b)
{
return 1;
}
else
return 0;
}
//遍历的aciotn函数
void action(const void *nodep,const VISIT which,const int depth)
{
int *datap;
switch(which)
{
case preorder://中序遍历，postorder前序遍历，endorder后序遍历
datap = *(int**)nodep;
printf("%d ",*datap);
break;
case leaf:
datap = *(int**)nodep;
printf("%d ",*datap);
break;
default:
break;
}
}
int main()
{
int i = 0;
int data[5] = {3,2,4,1,5};
int *p = data;
void *root = NULL;
void *val;
/*
tsearch函数：
如果rootp为NULL,则插入当前节点。
如果rootp不为NULL,利用compare进行比较，
如果相同则返回指向其父节点的指针
否则将当前节点加入树中，返回指向该节点在树中的位置
*/
for (i=0;i<5;i++)
{
//插入元素
val = tsearch(p,&root,compare);
if (val==NULL)
{
printf("insert data fail");
exit(1);
}
p++;
}
//树的遍历
twalk(root,action);
printf("\n");
val = tfind(p,&root,compare);
if (val==NULL)
{
printf("can not find the node %d\n",*p);
}
else
{
printf("find the node %d\n",**(int**)val); //注意：树存储的节点是指向int型指针的指针，int**
}
//是p指向二叉树中不存在的节点
p++;
val = tfind(p,&root,compare);
if (val==NULL)
{
printf("can not find the node %d\n",*p);
}
else
{
printf("find the node %d\n",**(int**)val);
}
//删除节点1
p = data;
val = tdelete(p,&root,compare);
if (val==NULL)
{
printf("can not find the node %d\n",*p);
}
else
{
printf("the parent node's value is %d\n",**(int**)val);
}
return 0;
}
/*
运行结果：
3 2 1 4 5
find the node 5
can not find the node -1079222440
the parent node's value is 4
*/