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

#define LENGTH(x) sizeof(x)/sizeof(x[0])

/**輸出數(shù)組元素
*\param arr:指向數(shù)組的指針
*\param len:數(shù)組元素的個(gè)數(shù)
*/
void print(char (*arr)[10],int len)
{
    int i;
    for (i=0;i<len;i++)
    {
        printf("%s ",arr[i]);
    }
    printf("\n");
}

int main()
{
    char arr[][10]={"bac","bca","abc","acb","cba","cab"}; /* 定義二維字符數(shù)組*/
    char *key="bca";/* 要查找的字符串*/
    char *ptr=NULL; /* 字符指針*/
 // 輸出未排序時(shí)字符數(shù)組的內(nèi)容
    printf("before qsort :");
    print(arr,LENGTH(arr));
    /* 使用qsort對(duì)字符數(shù)組排序*/
    qsort((void *)arr,LENGTH(arr),sizeof(arr[0]),(int (*)(const void *,const void *))strcmp);
    /* 輸出排序后字符數(shù)組的內(nèi)容*/
    printf("after qsort :");
    print(arr,LENGTH(arr));
    /* 采用二分查找查找指定字符*/
    ptr=(char *)bsearch(key,arr,LENGTH(arr),sizeof(arr[0]),(int (*)(const void *,const void *))strcmp);
    if(ptr)
    {
        /* 找到*/
        printf("%s is in the array\n",key);
    }
    else/* 沒(méi)找到*/
    {
        printf("%s isn't in the array\n",key);
    }
    return 0;
}

#include<stdlib.h>
#include<stdio.h>
#define ArrayLen(arr) (sizeof(arr) / sizeof(arr[0]))

int numarray[] = {123, 145, 512, 627, 800, 933};

int numeric (const int *p1, const int *p2)
{
    return(*p1 - *p2);
}
int* lookup(int key)
{//返回值是指向key的地址
    int *itemptr;
    // The cast of (int(*)(const void *,const void*)) is needed to avoid a type mismatch error at
 // compile time
    itemptr = (int *)bsearch(&key, numarray, ArrayLen(numarray), \
                             sizeof(int), (int(*)(const void *,const void *))numeric);
    return (itemptr);
}
int main(void)
{
 int *p = lookup(512);
 if(NULL != p)
  printf("找到的key是%d，", *p);

 printf("key的下標(biāo)是%d\n", (p - numarray));

    return 0;
}