写出二分查找算法的两种实现？

1)        递归方法实现：
int BSearch(elemtype a[],elemtype x,int low,int high)

{
  int mid;
  if(low>high) return -1;
  mid=(low+high)/2;
  if(x==a[mid]) return mid;
  if(x<a[mid]) return(BSearch(a,x,low,mid-1));
  else return(BSearch(a,x,mid+1,high));
}
2)        非递归方法实现：
int BSearch(elemtype a[],keytype key,int n)
{
  int low,high,mid;
  low=0;high=n-1;
  while(low<=high) 
   {
      mid=(low+high)/2;
      if(a[mid].key==key) return mid;
      else if(a[mid].key<key) low=mid+1;
      else high=mid-1;
   }
  return -1;
}