学步园

折半查找：适用于顺序序列

int BinSearch(int p[],int key)
{
	int low,high,mid;

	low=1;
	high=length_p;

	while(low<=high){
		mid=(low+high)/2;
		if(p[mid]==key)
			return mid;//查找成功
		else if(p[mid]>key)
			high=mid-1;
		else
			low=mid+1;
	}

	return 0;//查找不成功
}