C语言二分法查找的代码实现

二分法查找可以用循环和递归两种方式实现

#include <stdio.h>

typedef int DataType;
typedef unsigned int uint32;
typedef int int32;

#define SEARCH_LIST_SIZE (8)

int32 BinarySearch(DataType* plist, uint32 len, DataType item);         //循环方式
int32 BinarySearchRecur(DataType* plist, uint32 len, DataType item);    //递归方式


int main(int argc, char *const argv[])
{
    int32 ret = 0;
    DataType list[SEARCH_LIST_SIZE] = {1,2,3,4,5,6,7,8};

    if((ret = BinarySearchRecur(list, SEARCH_LIST_SIZE, 2)) != -1)
    {
        printf("Item is found, %d
", ret);
    }
    else
    {
        printf("Do not find
");
    }
    
}


/*----------------------------------------------------------------------
 * Function:    int BinarySearch(DataType * plist, uint32 len, DataType item)
 * Discription: 二分查找(循环方式)
 * Inputs:      plist, 指向被查找有序序列的指针；
 *              len, 被查找序列长度;
 *              item, 被查找数据
 * Outputs:     none
 * return:      -1, 未找到；
 *              -2, 输入参数异常；
 *              其他, 被查找元素对应的数组下标
 * ---------------------------------------------------------------------*/
int32 BinarySearch(DataType* plist, uint32 len, DataType item)
{
    uint32 icnt = 0;
    int32 min = 0, mid = 0, max = len-1;        //需定义为有符号类型

    if(plist == NULL)
    {
        return -2;
    }
    else
    {
        while(min <= max)
        {
            mid = (min + max)/2;

            if(plist[mid] < item)
            {
                min = mid + 1;
            }
            else if(plist[mid] > item)
            {
                max = mid - 1;
            }
            else
            {
                return mid; 
            }
        }

        return -1;
    }
    
}

/*----------------------------------------------------------------------
 * Function:    BinarySearchRecur(DataType* plist, uint32 len, DataType item)
 * Discription: 二分查找(递归方式)
 * Inputs:      plist, 指向被查找有序序列的指针；
 *              len, 被查找序列长度;
 *              item, 被查找数据
 * Outputs:     none
 * return:      -1, 未找到；
 *              -2, 输入参数异常；
 *              其他, 被查找元素对应的数组下标
 * ---------------------------------------------------------------------*/
int32 BinarySearchRecur(DataType* plist, uint32 len, DataType item)
{
    int32 min = 0, mid = 0, max = len-1;        //定义为有符号类型

    if(plist == NULL)
    {
        return -2;
    }
    else
    {
        while(min<=max)
        {
            mid = (min + max) / 2;

            if(plist[mid] < item)
            {
                min = mid + 1;
                BinarySearchRecur(&plist[min], max-min+1, item);
            }
            else if(plist[mid] > item)
            {
                max = mid - 1;
                BinarySearchRecur(&plist[min], max-min+1, item);
            }
            else
            {
                return mid; 
            }    
        }

        return -1;
    }
    
}