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;
}
}

}