C语言使用stdlib.h库函数的二分查找和快速排序的实现代码

快速排序：
复制代码 代码如下:
#include
#include
#include

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

void print(char (*arr)[10],int len)
{
    int i;
    for (i=0;i    {
        printf("%s ",arr[i]);
    }
    printf("n");
}

int main()
{
    char arr[][10]={"bac","bca","abc","acb","cba","cab"};
    char *key="bca";
    char *ptr=NULL;
 // 输出未排序时字符数组的内容
    printf("before qsort :");
    print(arr,LENGTH(arr));
   
    qsort((void *)arr,LENGTH(arr),sizeof(arr[0]),(int (*)(const void *,const void *))strcmp);
   
    printf("after qsort :");
    print(arr,LENGTH(arr));
   
    ptr=(char *)bsearch(key,arr,LENGTH(arr),sizeof(arr[0]),(int (*)(const void *,const void *))strcmp);
    if(ptr)
    {
       
        printf("%s is in the arrayn",key);
    }
    else
    {
        printf("%s isn't in the arrayn",key);
    }
    return 0;
}

二分查找：
复制代码 代码如下:
#include
#include
#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的下标是%dn", (p - numarray));

    return 0;
}