【C】二分查找法递归（函数）与非递归的两种实现

/*
*       当前版本：v1.0.1
*
*       作者：linqxxy
*
/*       修改日期：2019.3.28
/*
*	函数名称：Binsearch
*
*	函数功能：二分查找的递归实现方法
*
*	入口参数：arr,left，right，num
*
*	出口参数：空
*
*	返回类型：int
*/
int DGbinserch(int arr[],int left,int right,int num)
{
	int mid = 0;
	if (left>right)
	{
		return -1;
	}
	else
	{
		mid = (left + right) / 2;
		if (arr[mid] == num)
		{
			return mid;
		}
		else if (arr[mid] < num)
		{
			int ret = 0;
			ret=DGbinserch(arr, mid + 1, right, num);
			return ret;
		}
		else
		{
			int ret = 0;
			DGbinserch(arr, left, mid - 1, num);
			return ret;
		}
	}	
}

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<stdlib.h>

void main()
{
	int arr[] = { 1,3,5,7,9,11,13,15,17,19 };
	int key=0,mid=0, left = 0, right = sizeof(arr) / 4 - 1;
	printf("请输入要查找的数字：");
	scanf("%d", &key);
	for (left = 0; left <=right; )
	{
		mid = (left + right) / 2; 
		if (key>arr[mid])
		{
			left = mid+1;
		}
		else if (key < arr[mid])
		{
			right = mid-1;
		}
		else
		{
			break;
		}
	}	
	if(left<=right)
		printf("找到了\n"); 
	else
	{
		printf("没找到\n");
	}
	system("pause");
}