折半查找

#include<iostream.h>
void main()
{
	int a[]={1,2,3,4,5,6,7,8,9,10};
	int high=sizeof(a)/sizeof(int)-1,low=0,mid;
	while(1)
	{
		mid=(high+low)/2;
		if(a[mid]<9&&low<=high)
		{
			low=mid+1;
		}
		else if(a[mid]>9&&low<=high)
		{
			high=mid-1;
		}
		else if(a[mid]==9&&low<=high)
		{
			cout<<"所查关键字9为顺序表中第"<<mid+1<<"个位置"<<endl;
			break;
		}
		else
		{
			cout<<"查找失败"<<endl;break;
		}
	}
	
}