博客

#include "stdio.h"
int main()
{ 
	int a[10],right=0,left=9,n,mid;
	printf("Please input an arrylist from max to min:");
	for(int i=0;i<10;i++)
	scanf("%d",&a[i]);
	printf("Please input what number you wanna search:");
	scanf("%d",&n);
	while(right<=left)
	{
		mid=(right+left)/2;
		if(a[mid]<n)
		left=--mid;
		else if(a[mid]>n)
		right=++mid;
		else
		{
			printf("number has been found in the arrylist！");
			break; 
		}
		
	}
	if(right>left)
	printf("The number isn't in the arrylist!");
 } 

改进版本（函数递归版）

#include "stdio.h"
int midsearch(int arr[],int n)
{
	int mid,right,left=0;
	right=sizeof(arr)/4-1;             //用sizeof来计算数组的字节通过计算得到最后一个元素标记
	mid=(right+left)/2;
	if(arr[mid]<n)
	left=++mid;
	else if(arr[mid]>n)
	right=--mid;
	else if(arr[mid]==n)
	return 1;
	if(left<right)
	return midsearch(arr,n);       //如果没有查找到数据就进行递归
	else                          
	return -1;                 //下面为穷尽数据时的出口
	
}
int main()
{
	int a[10],n;
	printf("Please input an arrylist from min to max:");
	for(int i=0;i<10;i++)
	scanf("%d",&a[i]);
	printf("Please input what number you wanna search:");
	scanf("%d",&n); 
	if(midsearch(a,n)<0)
	printf(">.<The number isn't in the arrylist");
	else
	printf("^.^The nubmer has been found in the arrylist!");
	
}